ORCID Profile
0000-0003-1054-5285
Current Organisation
RMIT University
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Nanotechnology | Nanotechnology | Colloid and Surface Chemistry | Biomechanical Engineering | Biomedical Engineering | Powder and Particle Technology | Optical And Photonic Systems | Biotechnology Not Elsewhere Classified | Physical Chemistry (Incl. Structural) | Nanometrology | Nanoscale Characterisation | Biological Physics | Nanomanufacturing | Nanomaterials | Manufacturing Engineering | Manufacturing Processes and Technologies (excl. Textiles) | Metals and Alloy Materials |
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in Engineering | Soaps and cosmetics | Education and Training Systems not elsewhere classified | Manufacturing not elsewhere classified | Biological sciences | Chemical sciences | Processed food products and beverages not elsewhere classified | Physical sciences | Expanding Knowledge in Technology | Concentrating processes of other base metal ores | Expanding Knowledge in the Biological Sciences | Treatments (e.g. chemicals, antibiotics) | Coated Metal and Metal-Coated Products
Related Links
Publications
Highly selective trapping of enteropathogenic E. coli on Fabry-Perot sensor mirrors
Publisher: Elsevier BV
Date: 05-2012
DOI: 10.1016/J.BIOS.2012.03.019
Abstract: Untreated recycled water, such as sewage and graywater, will almost always contain a wide range of agents that are likely to present risks to human health, including chemicals and pathogenic microorganisms. The microbial hazards, such as large numbers of enteric pathogens that can cause gastroenteric illness if ingested, are the main cause of concern for human health. The presence of the enteropathogenic Escherichia coli (EPEC) serotype is of particular concern, as this group of bacteria is responsible for causing severe infant and travelers' diarrhea, gastroenteritis and hemolytic uremic syndrome. A biosensing system based on an optical Fabry-Pérot (FP) cavity, capable of directly detecting the presence of EPEC within 5 min, has been developed using a simple micro-thin double-sided adhesive tape and two semi-transparent FP mirror plates. The system utilizes a poly(methyl methacrylate) (PMMA) or glass substrates sputtered by 40-nm-thick gold thin films serving as FP mirrors. Mirrors have been activated using 0.1M mercaptopropionic acid, influencing an immobilization density of the translocated intimin receptor (TIR) of 100 ng/cm(2). The specificity of recognition was confirmed by exposing TIR functionalized surfaces to four taxonomically related and/or distantly related bacterial strains. It was found that the TIR-functionalized surfaces did not show any bacterial capture for these other bacterial strains within a 15 min incubation period.
The Bioeffects Resulting from Prokaryotic Cells and Yeast Being Exposed to an 18 GHz Electromagnetic Field
Publisher: Public Library of Science (PLoS)
Date: 08-07-2016
Imaging the air-water interface: Characterising biomimetic and natural hydrophobic surfaces using in situ atomic force microscopy
Publisher: Elsevier BV
Date: 02-2019
DOI: 10.1016/J.JCIS.2018.10.059
Abstract: The interface between water and a textured hydrophobic surface can exist in two regimes either the Wenzel (surface-engulfed) or Cassie-Baxter (water-suspended) state. Better understanding of the influence of pattern geometry and spacing is crucial for the design of functional (super)hydrophobic surfaces, as inspired by numerous ex les in nature. In this work, we have employed litude modulated - atomic force microscopy to visualize the air-water interface with an unprecedented degree of clarity on a superhydrophobic and a highly hydrophobic nanostructured surface. The images obtained provide the first real-time experimental visualization of the Cassie-Baxter wetting on the surface of biomimetic silicon nanopillars and a naturally superhydrophobic cicada wing. For both surfaces, the air-water interface was found to be remarkably well-defined, revealing a distinctly nanostructured air-water interface in the interstitial spacing. The degree of interfacial texture differed as a function of surface geometry. These results reveal that the air-water interface is heterogeneous in its structure and confirmed the presence of short-range interfacial ordering. Additionally, the overpressure values for each point on the interface were calculated, quantifying the difference in wetting behavior for the biomimetic and natural surface. Results suggest that highly-ordered, closely spaced nanofeatures facilitate robust Cassie-Baxter wetting states and therefore, can enhance the stability of (super)hydrophobic surfaces.
The Structural Diversity of Carbohydrate Antigens of Selected Gram-Negative Marine Bacteria
Publisher: MDPI AG
Date: 14-10-2011
DOI: 10.3390/MD9101914
The influence of particle size and contact angle in mineral flotation
Publisher: Elsevier BV
Date: 05-1988
Bactericidal activity of black silicon
Publisher: Springer Science and Business Media LLC
Date: 26-11-2013
DOI: 10.1038/NCOMMS3838
Wettability of natural superhydrophobic surfaces
Publisher: Elsevier BV
Date: 08-2014
DOI: 10.1016/J.CIS.2014.01.020
Abstract: Since the description of the 'Lotus Effect' by Barthlott and Neinhuis in 1997, the existence of superhydrophobic surfaces in the natural world has become common knowledge. Superhydrophobicity is associated with a number of possible evolutionary benefits that may be bestowed upon an organism, ranging from the ease of dewetting of their surfaces and therefore prevention of encumbrance by water droplets, self-cleaning and removal of particulates and potential pathogens, and even to antimicrobial activity. The superhydrophobic properties of natural surfaces have been attributed to the presence of hierarchical microscale (>1 μm) and nanoscale (typically below 200 nm) structures on the surface, and as a result, the generation of topographical hierarchy is usually considered of high importance in the fabrication of synthetic superhydrophobic surfaces. When one surveys the breadth of data available on naturally existing superhydrophobic surfaces, however, it can be observed that topographical hierarchy is not present on all naturally superhydrophobic surfaces in fact, the only universal feature of these surfaces is the presence of a sophisticated nanoscale structure. Additionally, several natural surfaces, e.g. those present on rose petals and gecko feet, display high water contact angles and high adhesion of droplets, due to the pinning effect. These surfaces are not truly superhydrophobic, and lack significant degrees of nanoscale roughness. Here, we discuss the phenomena of superhydrophobicity and pseudo-superhydrophobicity in nature, and present an argument that while hierarchical surface roughness may aid in the stability of the superhydrophobic effect, it is nanoscale surface architecture alone that is the true determinant of superhydrophobicity.
Natural Superhydrophobic Surfaces
Publisher: Elsevier
Date: 2015
Micro- to nano-scale chemical and mechanical mapping of antimicrobial-resistant fungal biofilms
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0NR05617K
Abstract: The heterogeneity of fungal biofilms are spatially characterized using a combination of AFM, nanoindentation, and ATR-FTIR.
Biological Interactions with Superhydrophobic Surfaces
Publisher: Elsevier
Date: 2015
Contact angles on particles and plates
Publisher: Elsevier BV
Date: 10-1987
PC 12 Pheochromocytoma Cell Response to Super High Frequency Terahertz Radiation from Synchrotron Source
Publisher: MDPI AG
Date: 31-01-2019
Abstract: High frequency (HF) electromagnetic fields (EMFs) have been widely used in many wireless communication devices, yet within the terahertz (THz) range, their effects on biological systems are poorly understood. In this study, electromagnetic radiation in the range of 0.3–19.5 × 1012 Hz, generated using a synchrotron light source, was used to investigate the response of PC 12 neuron-like pheochromocytoma cells to THz irradiation. The PC 12 cells remained viable and physiologically healthy, as confirmed by a panel of biological assays however, exposure to THz radiation for 10 min at 25.2 ± 0.4 °C was sufficient to induce a temporary increase in their cell membrane permeability. High-resolution transmission electron microscopy (TEM) confirmed cell membrane permeabilization via visualisation of the translocation of silica nanospheres (d = 23.5 ± 0.2 nm) and their clusters (d = 63 nm) into the PC 12 cells. Analysis of scanning electron microscopy (SEM) micrographs revealed the formation of atypically large (up to 1 µm) blebs on the surface of PC 12 cells when exposed to THz radiation. Long-term analysis showed no substantial differences in metabolic activity between the PC 12 cells exposed to THz radiation and untreated cells however, a higher population of the THz-treated PC 12 cells responded to the nerve growth factor (NGF) by extending longer neurites (up to 0–20 µm) compared to the untreated PC12 cells (up to 20 µm). These findings present implications for the development of nanoparticle-mediated drug delivery and gene therapy strategies since THz irradiation can promote nanoparticle uptake by cells without causing apoptosis, necrosis or physiological damage, as well as provide a deeper fundamental insight into the biological effects of environmental exposure of cells to electromagnetic radiation of super high frequencies.
Wing wettability of Odonata species as a function of quantity of epicuticular waxes
Publisher: Elsevier BV
Date: 11-2014
Thalassospira australica sp. nov. isolated from sea water
Publisher: Springer Science and Business Media LLC
Date: 14-05-2016
DOI: 10.1007/S10482-016-0710-9
Abstract: Two Gram-negative, non-pigmented, motile bacteria were isolated from a sea water s le collected at St. Kilda Beach, Port Philip Bay, Victoria, Australia. The two strains were found to grow between 4 and 40 °C, pH 5-10 and tolerate up to 10 % NaCl. A phylogenetic study, based on a 16S rRNA gene sequence analysis indicated that strains NP 3b2(T) and H 94 belong to the genus Thalassospira. The sequence similarity of the 16S rRNA gene between the two new isolates is 99.8 % and between these strains and all validly named Thalassospira species was found to be in the range of 95-99.4 %. The DNA-DNA relatedness between the two strains was found to be 80.2 %, while relatedness with other validly named species of the genus Thalassospira was between 53 and 65 %. The average nucleotide identity (ANI) and the in silico genome-to-genome distance (GGD) between the two bacteria and T. profundimaris WP0211(T), T. xiamenensis M-5(T), 'T. permensis' NBRC 106175(T) and T. lucentensis QMT2(T) was 76-82 % and 21-25 %, respectively. The results of phylogenetic and genomic analysis, together with physiological and biochemical properties, indicated that the two strains represent a new species of the genus Thalassospira. Based on these data, a new species, Thalassospira australica, is proposed with strain NP 3b2(T) (=KMM 6365(T) = JCM 31222(T)) as the type strain.
Nanotopography as a trigger for the microscale, autogenous and passive lysis of erythrocytes
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4TB00239C
Abstract: A mechano-responsive topology provides a highly active yet autogenous surface for erythrocyte lysis towards microfluidic haematology platforms.
Plastic degradation and its environmental implications with special reference to poly(ethylene terephthalate)
Publisher: MDPI AG
Date: 28-12-2013
DOI: 10.3390/POLYM5010001
Correction for López-Pérez et al., Genome Sequence of “Thalassospira australica” NP3b2 T Isolated from St. Kilda Beach, Tasman Sea
Publisher: American Society for Microbiology
Date: 26-02-2015
Bacterial Extracellular Polysaccharides Involved in Biofilm Formation
Publisher: MDPI AG
Date: 13-07-2009
Alteromonas australica sp. nov., isolated from the Tasman Sea
Publisher: Springer Science and Business Media LLC
Date: 06-01-2013
DOI: 10.1007/S10482-012-9869-X
Abstract: A non-pigmented, motile, Gram-negative bacterium designated H 17(T) was isolated from a seawater s le collected in Port Phillip Bay (the Tasman Sea, Pacific Ocean). The new organism displayed optimal growth between 4 and 37 °C, was found to be neutrophilic and slightly halophilic, tolerating salt water environments up to 10 % NaCl. Strain H 17(T) was found to be able to degrade starch and Tween 80 but unable to degrade gelatin or agar. Phosphatidylglycerol (27.7 %) and phosphatidylethanolamine (72.3 %) were found to be the only associated phospholipids. The major fatty acids identified are typical for the genus Alteromonas and include C16:0, C16:1ω7, C17:1ω8 and C18:1ω7. The G+C content of the DNA was found to be 43.4 mol%. A phylogenetic study, based on the 16S rRNA gene sequence analysis and Multilocus Phylogenetic Analysis, clearly indicated that strain H 17(T) belongs to the genus Alteromonas. The DNA-DNA relatedness between strain H 17(T) and the validly named Alteromonas species was between 30.7 and 46.4 mol%. Based on these results, a new species, Alteromonas australica, is proposed. The type strain is H 17(T) (= KMM 6016(T) = CIP 109921(T)).
Modifications to surface chemistry and nanotopography of poly(ethylene terephthalate) by marine bacteria
Publisher: IEEE
Date: 02-2010
Granulosicoccus coccoides sp. nov., isolated from leaves of seagrass (Zostera marina)
Publisher: Microbiology Society
Date: 04-2010
Abstract: A non-pigmented, motile, Gram-negative bacterium, strain Z 271 T , was isolated from the surface of leaves of the seagrass Zostera marina which was collected in Troitza Bay (Sea of Japan, Pacific Ocean). The new isolate grew between 5 °C and 28 °C and was slightly halophilic, tolerating environments containing up to 5 % (w/v) NaCl. Strain Z 271 T was able to degrade Tweens 20, 40 and 80 and partially degrade gelatin, but was unable to degrade casein. Phosphatidylethanolamine (36.9 %) and phosphatidylglycerol (63.1 %) were the predominant phospholipids. The major fatty acids included C 18 : 1 ω 7 c (43.7 %), C 16 : 1 ω 7 c (31.1 %) and C 16 : 0 (16.8 %). The main respiratory quinone was Q-8. The DNA–DNA relatedness value of strain Z 271 T with Granulosicoccus antarcticus IMCC3135 T was 35 %. The G+C content of the DNA of strain Z 271 T was 60.2 mol%. On the basis of phenotypic and genotypic characteristics and 16S rRNA gene sequence analysis, strain Z 271 T represents a novel species of the genus Granulosicoccus for which the name Granulosicoccus coccoides sp. nov. is proposed. The type strain is Z 271 T (=KMM 6014 T =CIP 109923 T ).
Three-dimensional reconstruction of surface nanoarchitecture from two-dimensional datasets
Publisher: Springer Science and Business Media LLC
Date: 10-01-2014
Abstract: The design of biomaterial surfaces relies heavily on the ability to accurately measure and visualize the three-dimensional surface nanoarchitecture of substrata. Here, we present a technique for producing three-dimensional surface models using displacement maps that are based on the data obtained from two-dimensional analyses. This technique is particularly useful when applied to scanning electron micrographs that have been calibrated using atomic force microscopy (AFM) roughness data. The evaluation of four different surface types, including thin titanium films, silicon wafers, polystyrene cell culture dishes and dragonfly wings confirmed that this technique is particularly effective for the visualization of conductive surfaces such as metallic titanium. The technique is particularly useful for visualizing surfaces that cannot be easily analyzed using AFM. The speed and ease with which electron micrographs can be recorded, combined with a relatively simple process for generating displacement maps, make this technique useful for the assessment of the surface topography of biomaterials.
Cd(II) binding by particulate low-rank coals in aqueous media: sorption characteristics and NICA–Donnan models
Publisher: Elsevier BV
Date: 10-2004
Tunable morphological changes of asymmetric titanium nanosheets with bactericidal properties
Publisher: Elsevier BV
Date: 02-2020
DOI: 10.1016/J.JCIS.2019.10.067
Abstract: Titanium and titanium alloys are often the most popular choice of material for the manufacture of medical implants however, they remain susceptible to the risk of device-related infection caused by the presence of pathogenic bacteria. Hydrothermal etching of titanium surfaces, to produce random nanosheet topologies, has shown remarkable ability to inactivate pathogenic bacteria via a physical mechanism. We expect that systematic tuning of the nanosheet morphology by controlling fabrication parameters, such as etching time, will allow for optimisation of the surface pattern for superior antibacterial efficacy. Using time-dependent hydrothermal processing of bulk titanium, we fabricated bactericidal nanosheets with variable nanoedge morphologies according to a function of etching time. A systematic study was performed to compare the bactericidal efficiency of nanostructured titanium surfaces produced at 0.5, 1, 2, 3, 4, 5, 6, 24 and 60 h of hydrothermal etching. Titanium surfaces hydrothermally treated for a period of 6 h were found to achieve maximal antibacterial efficiency of 99 ± 3% against Gram-negative Pseudomonas aeruginosa and 90 ± 9% against Gram-positive Staphylococcus aureus bacteria, two common human pathogens. These surfaces exhibited nanosheets with sharp edges of approximately 10 nm. The nanotopographies presented in this work exhibit the most efficient mechano-bactericidal activity against both Gram-negative and Gram-positive bacteria of any nanostructured titanium topography reported thus far.
The effect of polyterpenol thin film surfaces on bacterial viability and adhesion
Publisher: MDPI AG
Date: 28-01-2011
DOI: 10.3390/POLYM3010388
Review of the methods used for isolating pharmaceutical lead compounds from traditional medicinal plants
Publisher: Springer Science and Business Media LLC
Date: 23-02-2007
The effect of adsorbed and non-adsorbed additives on the stability of coal-water suspensions
Publisher: Elsevier BV
Date: 03-1996
Removal of aqueous toxic Hg(II) by functionalized mesoporous silica materials
Publisher: Wiley
Date: 19-03-2012
DOI: 10.1002/JCTB.3771
Draft genome sequences of Marinobacter similis A3d10Tand Marinobacter salarius R9SW1T
Publisher: American Society for Microbiology
Date: 26-06-2014
Abstract: Here, we present the draft genomes of Marinobacter similis A3d10 T , a potential plastic biodegrader, and Marinobacter salarius R9SW1 T , isolated from radioactive waters. This genomic information will contribute information on the genetic basis of the metabolic pathways for the degradation of both plastic and radionuclides.
Nano-structured antimicrobial surfaces: From nature to synthetic analogues
Publisher: Elsevier BV
Date: 12-2017
DOI: 10.1016/J.JCIS.2017.07.021
Abstract: The scientific and industrial interest in antimicrobial surfaces has significantly increased in recent times. This interest is largely in response to the persistent microbial contamination of industrial and, importantly, medical implant surfaces. Bacterial contamination of implant surfaces often leads to infection at the implant-tissue interface, and with the prevalence of increasing levels of antimicrobial resistance, the treatment of these infections is becoming far more challenging. Recently, many naturally occurring, high-aspect-ratio surface topographies have been discovered that exhibit high levels of biocidal efficacy. These include epicuticular lipid nano-architectures that are formed on the surfaces of insect wings, such as cicadae and dragonflies. The antimicrobial activity of such surfaces has been found to be a consequence of the physical interactions between the nanoscale topography of the substrate and the attaching pathogenic cells, meaning that the activity is independent of biochemical surface functionality. Importantly, these desirable surface properties can be translated to synthetic biomimetic surfaces, which, when mimicked, lead to a substantial increase in the antimicrobial properties of such surfaces. This paper reviews the recent advances in understanding the basis of these mechanical antimicrobial mechanisms, and discusses the progress being made towards the fabrication of optimised, biocompatible, synthetic analogues.
Bacterial-nanostructure interactions: the role of cell elasticity and adhesion forces
Publisher: Elsevier BV
Date: 06-2019
Impact of particle nanotopology on water transport through hydrophobic soils
Publisher: Elsevier BV
Date: 12-2015
DOI: 10.1016/J.JCIS.2015.08.029
Abstract: The impact of non- and poorly wetting soils has become increasingly important, due to its direct influence on the water-limited potential yield of rain-fed grain crops at a time of enhanced global competition for fresh water. This study investigates the physical and compositional mechanisms underlying the influence of soil organic matter (SOM) on the wetting processes of model systems. These model systems are directly related to two sandy wheat-producing soils that have contrasting hydrophobicities. Atomic force microscopy (AFM), contact angle and Raman micro-spectroscopy measurements on model planar and particulate SOM-containing surfaces demonstrated the role of the hierarchical surface structure on the wetting dynamics of packed particulate beds. It was found that a nanoscale surface topology is superimposed over the microscale roughness of the packed particles, and this controls the extent of water ingress into particulate packed beds of these particles. Using two of the dominant component organic species found in the SOM of the two soils used in this study, it was found that the specific interactions taking place between the SOM components, rather than their absolute quantities, dictated the formation of highly hydrophobic surface nanotopologies. This hydrophobicity was demonstrated, using micro-Raman imaging, to arise from the surface being in a composite Cassie-Baxter wetting state. Raman imaging demonstrated that the particle surface nanotopography influenced the degree of air entrapment in the interstices within the particle bed. The influence of a conventional surfactant on the wetting kinetics of both the model planar surfaces and packed particulate beds was quantified in terms of their respective advancing contact angles and the capillary wetting force vector. The information obtained for all of the planar and particulate surfaces, together with that obtained for the two soils, allowed linear relationships to be obtained in plots of the contact angle data as a function of the wetting liquid surface tensions. These linear relationships were found to reflect the mechanisms underlying the surface energy parameter requirements for wetting.
Specific Electromagnetic Effects of Microwave Radiation on Escherichia coli
Publisher: American Society for Microbiology
Date: 05-2011
DOI: 10.1128/AEM.01899-10
Abstract: The present study investigated the effects of microwave (MW) radiation applied under a sublethal temperature on Escherichia coli . The experiments were conducted at a frequency of 18 GHz and at a temperature below 40°C to avoid the thermal degradation of bacterial cells during exposure. The absorbed power was calculated to be 1,500 kW/m 3 , and the electric field was determined to be 300 V/m. Both values were theoretically confirmed using CST Microwave Studio 3D Electromagnetic Simulation Software. As a negative control, E. coli cells were also thermally heated to temperatures up to 40°C using Peltier plate heating. Scanning electron microscopy (SEM) analysis performed immediately after MW exposure revealed that the E. coli cells exhibited a cell morphology significantly different from that of the negative controls. This MW effect, however, appeared to be temporary, as following a further 10-min elapsed period, the cell morphology appeared to revert to a state that was identical to that of the untreated controls. Confocal laser scanning microscopy (CLSM) revealed that fluorescein isothiocyanate (FITC)-conjugated dextran (150 kDa) was taken up by the MW-treated cells, suggesting that pores had formed within the cell membrane. Cell viability experiments revealed that the MW treatment was not bactericidal, since 88% of the cells were recovered after radiation. It is proposed that one of the effects of exposing E. coli cells to MW radiation under sublethal temperature conditions is that the cell surface undergoes a modification that is electrokinetic in nature, resulting in a reversible MW-induced poration of the cell membrane.
Antipathogenic properties and applications of low-dimensional materials
Publisher: Springer Science and Business Media LLC
Date: 23-06-2021
DOI: 10.1038/S41467-021-23278-7
Abstract: A major health concern of the 21 st century is the rise of multi-drug resistant pathogenic microbial species. Recent technological advancements have led to considerable opportunities for low-dimensional materials (LDMs) as potential next-generation antimicrobials. LDMs have demonstrated antimicrobial behaviour towards a variety of pathogenic bacterial and fungal cells, due to their unique physicochemical properties. This review provides a critical assessment of current LDMs that have exhibited antimicrobial behaviour and their mechanism of action. Future design considerations and constraints in deploying LDMs for antimicrobial applications are discussed. It is envisioned that this review will guide future design parameters for LDM-based antimicrobial applications.
Adsorption of Human Plasma Albumin and Fibronectin onto Nanostructured Black Silicon Surfaces
Publisher: American Chemical Society (ACS)
Date: 10-10-2016
DOI: 10.1021/ACS.LANGMUIR.6B02601
Abstract: The protein adsorption of two human plasma proteins-albumin (Alb) and fibronectin (Fn)-onto synthetic nanostructured bactericidal material-black silicon (bSi) surfaces (that contain an array of nanopillars) and silicon wafer (nonstructured) surfaces-was investigated. The adsorption behavior of Alb and Fn onto two types of substrata was studied using a combination of complementary analytical techniques. A two-step Alb adsorption mechanism onto the bSi surface has been proposed. At low bulk concentrations (below 40 μg/mL), the Alb preferentially adsorbed at the base of the nanopillars. At higher bulk concentrations, the Alb adsorbed on the top of the nanopillars. In the case of Fn, the protein preferentially adsorbed on the top of the nanopillars, irrespective of its bulk concentration.
Australian colloid and surface science in 2007
Publisher: CSIRO Publishing
Date: 2007
DOI: 10.1071/CH07293
Antibacterial surfaces
Publisher: Springer International Publishing
Date: 2015
Adsorption and coprecipitation of heavy metals from ammoniacal solutions using hydrous metal oxides
Publisher: Elsevier BV
Date: 06-1997
High-spatial-resolution mapping of superhydrophobic cicada wing surface chemistry using infrared microspectroscopy and infrared imaging at two synchrotron beamlines
Publisher: International Union of Crystallography (IUCr)
Date: 22-03-2013
DOI: 10.1107/S0909049513004056
Abstract: The wings of some insects, such as cicadae, have been reported to possess a number of interesting and unusual qualities such as superhydrophobicity, anisotropic wetting and antibacterial properties. Here, the chemical composition of the wings of the Clanger cicada ( Psaltoda claripennis ) were characterized using infrared (IR) microspectroscopy. In addition, the data generated from two separate synchrotron IR facilities, the Australian Synchrotron Infrared Microspectroscopy beamline (AS-IRM) and the Synchrotron Radiation Center (SRC), University of Wisconsin-Madison, IRENI beamline, were analysed and compared. Characteristic peaks in the IR spectra of the wings were assigned primarily to aliphatic hydrocarbon and amide functionalities, which were considered to be an indication of the presence of waxy and proteinaceous components, respectively, in good agreement with the literature. Chemical distribution maps showed that, while the protein component was homogeneously distributed, a significant degree of heterogeneity was observed in the distribution of the waxy component, which may contribute to the self-cleaning and aerodynamic properties of the cicada wing. When comparing the data generated from the two beamlines, it was determined that the SRC IRENI beamline was capable of producing higher-spatial-resolution distribution images in a shorter time than was achievable at the AS-IRM beamline, but that spectral noise levels per pixel were considerably lower on the AS-IRM beamline, resulting in more favourable data where the detection of weak absorbances is required. The data generated by the two complementary synchrotron IR methods on the chemical composition of cicada wings will be immensely useful in understanding their unusual properties with a view to reproducing their characteristics in, for ex le, industry applications.
Preparation of sinapinaldehyde modified mesoporous silica materials and their application in selective extraction of trace Pb(II)
Publisher: Informa UK Limited
Date: 10-2013
Comparative genomics of pathogens
Publisher: Springer New York
Date: 03-10-2010
Efficient surface modification of biomaterial to prevent biofilm formation and the attachment of microorganisms
Publisher: Springer Science and Business Media LLC
Date: 18-05-2012
DOI: 10.1007/S00253-012-4144-7
Abstract: Biomaterials play a fundamental role in disease management and the improvement of health care. In recent years, there has been a significant growth in the ersity, function, and number of biomaterials used worldwide. Yet, attachment of pathogenic microorganisms onto biomaterial surfaces remains a significant challenge that substantially undermines their clinical applicability, limiting the advancement of these systems. The emergence and escalating pervasiveness of antibiotic-resistant bacterial strains makes the management of biomaterial-associated nosocomial infections increasingly difficult. The conventional post-operative treatment of implant-caused infections using systemic antibiotics is often marginally effective, further accelerating the extent of antimicrobial resistance. Methods by which the initial stages of bacterial attachment and biofilm formation can be restricted or prevented are therefore sought. The surface modification of biomaterials has the potential to alleviate pathogenic biofouling, therefore preventing the need for conventional antibiotics to be applied.
Broad-spectrum treatment of bacterial biofilms using magneto-responsive liquid metal particles
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0TB01655A
Abstract: Broad-spectrum treatment of monoculture and mixed species biofilms using magnetically actuated, liquid metal particles.
Poly(ethylene terephthalate) polymer surfaces as a substrate for bacterial attachment and biofilm formation
Publisher: Japanese Society of Microbial Ecology
Date: 2009
Abstract: Plastic debris causes extensive damage to the marine environment, largely due to its ability to resist degradation. Attachment on plastic surfaces is a key initiation process for their degradation. The tendency of environmental marine bacteria to adhere to poly(ethylene terephthalate) (PET) plastic surfaces as a model material was investigated. It was found that the overall number of heterotrophic bacteria in a s le of sea water taken from St. Kilda Beach, Melbourne, Australia, was significantly reduced after six months from 4.2-4.7×10(3) cfu mL(-1) to below detectable levels on both full-strength and oligotrophic marine agar plates. The extinction of oligotrophs after six months was detected in all s les. In contrast, the overall bacterial number recovered on full strength marine agar from the s le flasks with PET did not dramatically reduce. Heterotrophic bacteria recovered on full-strength marine agar plates six months after the commencement of the experiment were found to have suitable metabolic activity to survive in sea water while attaching to the PET plastic surface followed by the commencement of biofilm formation.
Introduction to antibacterial surfaces
Publisher: Springer International Publishing
Date: 2015
The wetting behaviour of several organic liquids in water on coal surfaces
Publisher: Elsevier BV
Date: 1996
Natural antibacterial surfaces
Publisher: Springer International Publishing
Date: 2015
Cd(II) sorption onto chemically modified Australian coals
Publisher: Elsevier BV
Date: 12-04-2005
The Design of Superhydrophobic Surfaces
Publisher: Elsevier
Date: 2015
Designing antibacterial surfaces for biomedical implants
Publisher: Springer International Publishing
Date: 2015
Bacterial extracellular polysaccharides
Publisher: Springer Netherlands
Date: 2011
DOI: 10.1007/978-94-007-0940-9_13
Abstract: Extracellular polysaccharides are as structurally and functionally erse as the bacteria that synthesise them. They can be present in many forms, including cell-bound capsular polysaccharides, unbound "slime", and as O-antigen component of lipopolysaccharide, with an equally wide range of biological functions. These include resistance to desiccation, protection against nonspecific and specific host immunity, and adherence. Unsurprisingly then, much effort has been made to catalogue the enormous structural complexity of the extracellular polysaccharides made possible by the wide assortment of available monosaccharide combinations, non-carbohydrate residues, and linkage types, and to elucidate their biosynthesis and export. In addition, the work is driven by the commercial potential of these microbial substances in food, pharmaceutics and biomedical industries. Most recently, bacteria-mediated environmental restoration and bioleaching have been attracting much attention owing to their potential to remediate environmental effluents produced by the mining and metallurgy industries. In spite of technological advances in chemistry, molecular biology and imaging techniques that allowed for considerable expansion of knowledge pertaining to the bacterial surface polysaccharides, current understanding of the mechanisms of synthesis and regulation of extracellular polysaccharides is yet to fully explain their structural intricacy and functional variability.
Plasma-assisted surface modification of organic biopolymers to prevent bacterial attachment
Publisher: Elsevier BV
Date: 05-2011
DOI: 10.1016/J.ACTBIO.2010.12.024
Abstract: Despite many synthetic biomaterials having physical properties that are comparable or even superior to those of natural body tissues, they frequently fail due to the adverse physiological reactions they cause within the human body, such as infection and inflammation. The surface modification of biomaterials is an economical and effective method by which biocompatibility and biofunctionality can be achieved while preserving the favorable bulk characteristics of the biomaterial, such as strength and inertness. Amongst the numerous surface modification techniques available, plasma surface modification affords device manufacturers a flexible and environmentally friendly process that enables tailoring of the surface morphology, structure, composition, and properties of the material to a specific need. There are a vast range of possible applications of plasma modification in biomaterial applications, however, the focus of this review paper is on processes that can be used to develop surface morphologies and chemical structures for the prevention of adhesion and proliferation of pathogenic bacteria on the surfaces of in-dwelling medical devices. As such, the fundamental principles of bacterial cell attachment and biofilm formation are also discussed. Functional organic plasma polymerised coatings are also discussed for their potential as biosensitive interfaces, connecting inorganic/metallic electronic devices with their physiological environments.
Tumor FAK orchestrates immunosuppression in ovarian cancer via the CD155/TIGIT axis
Publisher: Proceedings of the National Academy of Sciences
Date: 25-04-2022
Abstract: High-grade serous ovarian carcinoma (HGSOC) is an immunotherapy-resistant lethal cancer. An HGSOC hallmark is elevated checkpoint pathway ligand expression that limits antitumor immune responses. Computational, preclinical, and patient tumor multiplexed analyses revealed that tumor-associated focal adhesion kinase (FAK) activation regulates CD155 expression, a checkpoint ligand for TIGIT (T cell immunoreceptor with immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domains). Using an aggressive mouse ovarian tumor model, we find that combined oral FAK inhibitor plus function-blocking TIGIT antibody immunotherapy reduced tumor burden, prolonged mouse survival, and led to immune cell activation and tertiary lymphoid structure formation, hallmarks of an antitumor immune response. As FAK is commonly overexpressed in HGSOC tumors, targeting FAK and TIGIT may limit tumor immune evasion.
Updating the taxonomic toolbox: classification of Alteromonas spp. using multilocus phylogenetic analysis and MALDI-TOF mass spectrometry
Publisher: Springer Science and Business Media LLC
Date: 11-09-2012
DOI: 10.1007/S10482-012-9807-Y
Abstract: Bacteria of the genus Alteromonas are Gram-negative, strictly aerobic, motile, heterotrophic marine bacteria known for their versatile metabolic activities. Identification and classification of novel species belonging to the genus Alteromonas generally involves DNA-DNA hybridization (DDH) as distinct species often fail to be resolved at the 97 % threshold value of the 16S rRNA gene sequence similarity. In this study, the applicability of Multilocus Phylogenetic Analysis (MLPA) and Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) for the differentiation of Alteromonas species has been evaluated. Phylogenetic analysis incorporating five house-keeping genes (dnaK, sucC, rpoB, gyrB, and rpoD) revealed a threshold value of 98.9 % that could be considered as the species cut-off value for the delineation of Alteromonas spp. MALDI-TOF MS data analysis reconfirmed the Alteromonas species clustering. MLPA and MALDI-TOF MS both generated data that were comparable to that of the 16S rRNA gene sequence analysis and may be considered as useful complementary techniques for the description of new Alteromonas species.
Antibacterial titanium nano-patterned arrays inspired by dragonfly wings
Publisher: Springer Science and Business Media LLC
Date: 18-11-2015
DOI: 10.1038/SREP16817
Abstract: Titanium and its alloys remain the most popular choice as a medical implant material because of its desirable properties. The successful osseointegration of titanium implants is, however, adversely affected by the presence of bacterial biofilms that can form on the surface and hence methods for preventing the formation of surface biofilms have been the subject of intensive research over the past few years. In this study, we report the response of bacteria and primary human fibroblasts to the antibacterial nanoarrays fabricated on titanium surfaces using a simple hydrothermal etching process. These fabricated titanium surfaces were shown to possess selective bactericidal activity, eliminating almost 50% of Pseudomonas aeruginosa cells and about 20% of the Staphylococcus aureus cells coming into contact with the surface. These nano-patterned surfaces were also shown to enhance the aligned attachment behavior and proliferation of primary human fibroblasts over 10 days of growth. These antibacterial surfaces, which are capable of exhibiting differential responses to bacterial and eukaryotic cells, represent surfaces that have excellent prospects for biomedical applications.
“Race for the Surface”: Eukaryotic Cells Can Win
Publisher: American Chemical Society (ACS)
Date: 16-08-2016
Abstract: With an aging population and the consequent increasing use of medical implants, managing the possible infections arising from implant surgery remains a global challenge. Here, we demonstrate for the first time that a precise nanotopology provides an effective intervention in bacterial cocolonization enabling the proliferation of eukaryotic cells on a substratum surface, preinfected by both live Gram-negative, Pseudomonas aeruginosa, and Gram-positive, Staphylococcus aureus, pathogenic bacteria. The topology of the model black silicon (bSi) substratum not only favors the proliferation of eukaryotic cells but is biocompatible, not triggering an inflammatory response in the host. The attachment behavior and development of filopodia when COS-7 fibroblast cells are placed in contact with the bSi surface are demonstrated in the dynamic study, which is based on the use of real-time sequential confocal imaging. Bactericidal nanotopology may enhance the prospect for further development of inherently responsive antibacterial nanomaterials for bionic applications such as prosthetics and implants.
The role of surface thermodynamic properties in the agglomeration of coals
Publisher: Elsevier BV
Date: 08-1992
Bacterial interactions with optical fibre surfaces
Publisher: IEEE
Date: 02-2010
The idiosyncratic self-cleaning cycle of bacteria on regularly arrayed mechano-bactericidal nanostructures
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9NR05923G
Abstract: Bacterial cells are lysed when they attach onto regularly arrayed silicon nanopillars. Following cell lysis, the cell debris detaches from the surface and is released back into the immediate environment which allows for restored bactericidal activity of the substratum.
Nature inspired structured surfaces for biomedical applications
Publisher: Bentham Science Publishers Ltd.
Date: 08-2011
DOI: 10.2174/092986711796504673
Abstract: Nature has created an array of superhydrophobic surfaces that possess water-repellent, self-cleaning and anti-icing properties. These surfaces have a number of potential applications in the biomedical industry, as they have the potential to control protein adsorption and cell adhesion. Natural superhydrophobic surfaces are typically composed of materials with a low intrinsic surface free-energy (e.g the cuticular waxes of lotus leaves and insect wings) with a hierarchical structural configuration. This hierarchical surface topography acts to decrease the contact area of water droplets in contact with the surface, thereby increasing the extent of the air/water interface, resulting in water contact angles greater than 150º. In order to employ these surfaces in biotechnological applications, fabrication techniques must be developed so that these multi-scale surface roughness characteristics can be reproduced. Additionally, these fabrication techniques must also be able to be applied to the material required for the intended application. An overview of some of the superhydrophobic surfaces that exist in nature is presented, together with an explanation of the theories of their wettability. Also included is a description of some of the biomedical applications of superhydrophobic surfaces and fabrication techniques that can be used to mimic superhydrophobic surfaces found in nature.
Erratum: 18 GHz electromagnetic field induces permeability of Gram-positive cocci (Scientific Reports (2015) 5 (10980) doi: 10.1038/srep10980))
Publisher: Springer Science and Business Media LLC
Date: 02-09-2015
DOI: 10.1038/SREP13507
Abstract: The effect of electromagnetic field (EMF) exposures at the microwave (MW) frequency of 18 GHz, on four cocci, Planococcus maritimus KMM 3738, Staphylococcus aureus CIP 65.8 T , S. aureus ATCC 25923 and S. epidermidis ATCC 14990 T , was investigated. We demonstrate that exposing the bacteria to an EMF induced permeability in the bacterial membranes of all strains studied, as confirmed directly by transmission electron microscopy (TEM), and indirectly via the propidium iodide assay and the uptake of silica nanospheres. The cells remained permeable for at least nine minutes after EMF exposure. It was shown that all strains internalized 23.5 nm nanospheres, whereas the internalization of the 46.3 nm nanospheres differed amongst the bacterial strains ( S. epidermidis ATCC 14990 T ~ 0% Staphylococcus aureus CIP 65.8 T S. aureus ATCC 25923, ~40% Planococcus maritimus KMM 3738, ~80%). Cell viability experiments indicated that up to 84% of the cells exposed to the EMF remained viable. The morphology of the bacterial cells was not altered, as inferred from the scanning electron micrographs, however traces of leaked cytosolic fluids from the EMF exposed cells could be detected. EMF-induced permeabilization may represent an innovative, alternative cell permeability technique for applications in biomedical engineering, cell drug delivery and gene therapy.
Physico-mechanical characterisation of cells using atomic force microscopy - Current research and methodologies
Publisher: Elsevier BV
Date: 08-2011
DOI: 10.1016/J.MIMET.2011.05.021
Abstract: Atomic force microscopy (AFM) is a technique that has long been employed in materials science, but is now increasingly being used in the biological sciences. AFM provides excellent topographical information on prokaryotic and eukaryotic cell surfaces, and the extracellular material produced by the cells. It helps to generate important data on the mechanical properties of cells, such as hardness and elasticity. AFM can also be used to measure the strength of adhesion, attraction, and repulsion forces between cells and surfaces or even between in idual molecules. Additionally, by combining AFM with other complementary techniques such as fluorescence microscopy or Raman spectroscopy, the chemistry of given surface structures can be identified. This review aims to provide an update on the AFM techniques currently used in cell biology studies, along with a description of the range of recently developed research methodologies in which AFM plays a key role.
Graphene Induces Formation of Pores That Kill Spherical and Rod-Shaped Bacteria
Publisher: American Chemical Society (ACS)
Date: 21-07-2015
Abstract: Pristine graphene, its derivatives, and composites have been widely reported to possess antibacterial properties. Most of the studies simulating the interaction between bacterial cell membranes and the surface of graphene have proposed that the graphene-induced bacterial cell death is caused either by (1) the insertion of blade-like graphene-based nanosheets or (2) the destructive extraction of lipid molecules by the presence of the lipophilic graphene. These simulation studies have, however, only take into account graphene-cell membrane interactions where the graphene is in a dispersed form. In this paper, we report the antimicrobial behavior of graphene sheet surfaces in an attempt to further advance the current knowledge pertaining to graphene cytotoxicity using both experimental and computer simulation approaches. Graphene nanofilms were fabricated to exhibit different edge lengths and different angles of orientation in the graphene sheets. These substrates were placed in contact with Pseudomonas aeruginosa and Staphylococcus aureus bacteria, where it was seen that these substrates exhibited variable bactericidal efficiency toward these two pathogenic bacteria. It was demonstrated that the density of the edges of the graphene was one of the principal parameters that contributed to the antibacterial behavior of the graphene nanosheet films. The study provides both experimental and theoretical evidence that the antibacterial behavior of graphene nanosheets arises from the formation of pores in the bacterial cell wall, causing a subsequent osmotic imbalance and cell death.
Natural Insect and Plant Micro-/Nanostructsured Surfaces: An Excellent Selection of Valuable Templates with Superhydrophobic and Self-Cleaning Properties
Publisher: MDPI AG
Date: 02-09-2014
Translocation of silica nanospheres through giant unilamellar vesicles (GUVs) induced by a high frequency electromagnetic field
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1RA05459G
Abstract: Membrane model systems capable of mimicking live cell membranes were used for the first time in studying the effects arising from electromagnetic fields (EMFs) of 18 GHz where membrane permeability was observed following exposure.
The influence of surfactant adsorption on the surface characterisation of Australian coals
Publisher: Elsevier BV
Date: 02-2001
Three-dimensional visualization of nanostructured surfaces and bacterial attachment using Autodesk (R) Maya (R)
Publisher: Springer Science and Business Media LLC
Date: 28-02-2014
DOI: 10.1038/SREP04228
Fabrication of a platform to isolate the influences of surface nanotopography from chemistry on bacterial attachment and growth
Publisher: American Vacuum Society
Date: 26-02-2015
DOI: 10.1116/1.4913377
Abstract: Billions of dollars are spent annually worldwide to combat the adverse effects of bacterial attachment and biofilm formation in industries as varied as maritime, food, and health. While advances in the fabrication of antifouling surfaces have been reported recently, a number of the essential aspects responsible for the formation of biofilms remain unresolved, including the important initial stages of bacterial attachment to a substrate surface. The reduction of bacterial attachment to surfaces is a key concept in the prevention or minimization of biofilm formation. The chemical and physical characteristics of both the substrate and bacteria are important in understanding the attachment process, but substrate modification is likely the most practical route to enable the extent of bacterial attachment taking place to be effectively controlled. The microtopography and chemistry of the surface are known to influence bacterial attachment. The role of surface chemistry versus nanotopography and their interplay, however, remain unclear. Most methods used for imparting nanotopographical patterns onto a surface also induce changes in the surface chemistry and vice versa. In this study, the authors combine colloidal lithography and plasma polymerization to fabricate homogeneous, reproducible, and periodic nanotopographies with a controllable surface chemistry. The attachment of Escherichia coli bacteria onto carboxyl (plasma polymerized acrylic acid, ppAAc) and hydrocarbon (plasma polymerized octadiene, ppOct) rich plasma polymer films on either flat or colloidal array surfaces revealed that the surface chemistry plays a critical role in bacterial attachment, whereas the effect of surface nanotopography on the bacterial attachment appears to be more difficult to define. This platform represents a promising approach to allow a greater understanding of the role that surface chemistry and nanotopography play on bacterial attachment and the subsequent biofouling of the surface.
The Zeta Potential of Iron and Chromium Hydrous Oxides during Adsorption and Coprecipitation of Aqueous Heavy Metals
Publisher: Elsevier BV
Date: 08-1996
Ecophysiological diversity of a novel member of the genus Alteromonas, and description of Alteromonas mediterranea sp. nov.
Publisher: Springer Science and Business Media LLC
Date: 19-10-2014
DOI: 10.1007/S10482-014-0309-Y
Abstract: Nine non-pigmented, motile, Gram-negative bacteria originally designated as Alteromonas macleodii deep-sea ecotypes, were isolated from seawater s les collected from four separate locations two deep-sea sites in the Mediterranean Sea and surface water of the Aegean Sea and English Channel. The six strains studied in vitro were found to tolerate up to 20 % NaCl. The DNA-DNA relatedness between the deep-sea ecotype strains was found to be between 75 and 89 %, whilst relatedness with the validly named Alteromonas species was found to be between 31 and 69 %. The average nucleotide identity (ANI) amongst the deep-sea ecotype strains was found to be 98-100 % the in silico genome-to-genome distance (GGD), 85-100 % the average amino acid identity (AAI) of all conserved protein-coding genes, 95-100 % and the strains possessed 30-32 of the Karlin's genomic signature dissimilarity. The ANI between the deep-sea ecotype strains and A. macleodii ATCC 27126(T) and Alteromonas australica H 17(T) was found to be 80.6 and 74.6 %, respectively. A significant correlation was observed between the phenotypic data obtained in vitro and data retrieved in silico from whole genome sequences. The results of a phylogenetic study that incorporated a 16S rRNA gene sequence analysis, multilocus phylogenetic analysis (MLPA) and genomic analysis, together with the physiological, biochemical and chemotaxonomic data, clearly indicated that the group of deep-sea ecotype strains represents a distinct species within the genus Alteromonas. Based on these data, a new species, Alteromonas mediterranea, is proposed. The type strain is DE(T) ( = CIP 110805(T) = LMG 28347(T) = DSM 17117(T)).
Biophysical model of bacterial cell interactions with nanopatterned cicada wing surfaces
Publisher: Elsevier BV
Date: 02-2013
Antibacterial compounds from Planchonia careya leaf extracts
Publisher: Elsevier BV
Date: 03-2008
DOI: 10.1016/J.JEP.2008.01.007
Abstract: The leaves of Planchonia careya (F. Muell.) R. Knuth (Lecythidaceae) have been traditionally implemented in the treatment of wounds by the indigenous people of northern Australia, although the compounds responsible for the medicinal properties have not been identified. In this study, antibacterial compounds from the leaf extracts were isolated and characterized, and the biological activity of each compound was assessed. Compounds were isolated from the leaf extracts using HPLC-piloted activity-guided fractionation. The minimum inhibitory concentrations (MICs) were assessed with plate-hole diffusion assays, and the cytotoxicity was determined with MTT assays using monkey kidney epithelial (MA104) cells. Six known compounds were isolated from the leaf extracts and were identified as 1, (+)-gallocatechin 2, gallocatechin-(4alpha-->8)-gallocatechin 3, 9(S)-hydroxy-10E,12Z-octadecadienoic acid (alpha-dimorphecolic acid) 4, 2alpha,3beta,24-trihydroxyolean-12-en-28-oic acid (hyptatic acid-A) 5, 3beta-O-cis-p-coumaroyltormentic acid and 6, 3beta-O-trans-p-coumaroyltormentic acid. Compounds 5 and 6 were weakly selective for vancomycin-resistant Enterococcus (VRE) compared with eukaryotic cells, with an MIC of 59.4microg/mL and a 50% inhibitory concentration (IC(50)) of 72.0microg/mL for MA104 cells. The isolation of six antibacterial compounds from the leaves of Planchonia careya validates the use of this species as a topical wound-healing remedy.
The influence of coal rank and mineral matter content on contact angle hysteresis
Publisher: Elsevier BV
Date: 05-1994
Marinobacter salarius sp. nov. and Marinobacter similis sp. nov., Isolated from Sea Water
Publisher: Public Library of Science (PLoS)
Date: 08-09-2014
Review of the specific effects of microwave radiation on bacterial cells
Publisher: Springer Science and Business Media LLC
Date: 09-08-2012
DOI: 10.1007/S00253-012-4339-Y
Abstract: The aim of the present review was to evaluate the literature suggesting that consideration be given to the existence of specific microwave (MW) effects on prokaryotic microorganisms that is, effects on organisms that cannot be explained by virtue of temperature increases alone. This review considered a range of the reported effects on cellular components including membranes, proteins, enzyme activity as well as cell death. It is concluded that the attribution of such effects to non-thermal mechanisms is not justified due to poor control protocols and because of the possibility that an unmeasurable thermal force, relating to instantaneous temperature (T (i)) that occurs during MW processing, has not been taken into account. However, due to this lack of control over T (i), it also follows that it cannot be concluded that these effects are not 'non-thermal'. Due to this ambiguity, it is proposed that internal 'micro'-thermal effects may occur that are specific to MW radiation, given its inherent unusual energy deposition patterning.
The Evolution of Silica Nanoparticle-polyester Coatings on Surfaces Exposed to Sunlight
Publisher: MyJove Corporation
Date: 11-10-2016
DOI: 10.3791/54309
The role of metal ion-ligand interactions during divalent metal ion adsorption
Publisher: Elsevier BV
Date: 09-2015
DOI: 10.1016/J.JCIS.2015.04.056
Abstract: A suite of seven different alent metal ions (Ca(II), Cd(II), Cu(II), Mg(II), Ni(II), Pb(II), Zn(II)) was adsorbed from solution onto two Fe2O3 s les, quartz SiO2 and three different hoteric polystyrene latices (containing amine and carboxyl functional groups). For the metal oxides, a high correlation was observed between the pH at which 50% of the metal was removed from solution (pH50) and the first hydrolysis constant for the metal ion (pK1). For the polystyrene latices, a much higher correlation was observed between the pH50 and pKc (equilibrium constant describing metal-carboxyl affinity) as opposed to pK1. These observations provide evidence of a strong relationship that exists between a metal's affinity for a particular ligand in solution and for that metal ion's affinity for the same ligand present as part of an adsorbing surface. The isoelectric point of the hoteric latex surface can be increased by decreasing the carboxyl content of the latex surface. For all 7 metal ions, this resulted in a substantial decrease, for any given pH, in adsorption. We suggest that this may be partly due to the decreased carboxyl content, but is dominantly attributable to the presence of less favorable electrostatic conditions. This, in turn, demonstrates that electrostatics play a controlling role in metal ion adsorption onto hoteric latex surfaces and, in addition to the nature of the metal ion, also controls the pH at which adsorption takes place.
Genome Sequence of “Thalassospira australica” NP3b2 T Isolated from St. Kilda Beach, Tasman Sea
Publisher: American Society for Microbiology
Date: 24-12-2014
Abstract: Here, we present the draft genome of “ Thalassospira australica ” NP3b2 T , a potential poly(ethylene terephthalate) (PET) plastic biodegrader. This genomic information will enhance information on the genetic basis of metabolic pathways for the degradation of PET plastic.
Bacterial patterning at the three-phase line of contact with microtextured alkanes
Publisher: Informa UK Limited
Date: 16-03-2015
DOI: 10.1080/08927014.2015.1038706
Abstract: Aliphatic crystallites, characteristic of the eicosane and docosane components of naturally occurring lipids, were found to form microtextures that were structured by specific interactions with ordered graphite (HOPG) used as the underlying substratum, as confirmed by scanning electron microscopy (SEM) and fast Fourier transform (FFT) analysis. Confocal scanning laser microscopy (CLSM) showed highly directed bacterial alignment for two bacterial species (spherical and rod-shaped), reflecting the preferential orientation of the crystallite-air-water interfaces to give linear and triangular bacterial patterning. The mechanisms of bacterial attachment are demonstrated in terms of the balance between effective radial adhesional forces and the capillary forces resulting from the water contact angle of the bacteria at the three-phase line (TPL) of the lipid surface. It is suggested that these microtextured surfaces, which exhibit the ability to limit bacterial adhesion to a precise patterning at the lipid TPL, could be used as a means of controlling bacterial colonization.
18 GHz electromagnetic field induces permeability of Gram-positive cocci
Publisher: Springer Science and Business Media LLC
Date: 16-06-2015
DOI: 10.1038/SREP10980
Abstract: The effect of electromagnetic field (EMF) exposures at the microwave (MW) frequency of 18 GHz, on four cocci, Planococcus maritimus KMM 3738, Staphylococcus aureus CIP 65.8 T , S. aureus ATCC 25923 and S. epidermidis ATCC 14990 T , was investigated. We demonstrate that exposing the bacteria to an EMF induced permeability in the bacterial membranes of all strains studied, as confirmed directly by transmission electron microscopy (TEM) and indirectly via the propidium iodide assay and the uptake of silica nanospheres. The cells remained permeable for at least nine minutes after EMF exposure. It was shown that all strains internalized 23.5 nm nanospheres, whereas the internalization of the 46.3 nm nanospheres differed amongst the bacterial strains ( S. epidermidis ATCC 14990 T ~ 0% Staphylococcus aureus CIP 65.8 T S. aureus ATCC 25923, ~40% Planococcus maritimus KMM 3738, ~80%). Cell viability experiments indicated that up to 84% of the cells exposed to the EMF remained viable. The morphology of the bacterial cells was not altered, as inferred from the scanning electron micrographs, however traces of leaked cytosolic fluids from the EMF exposed cells could be detected. EMF-induced permeabilization may represent an innovative, alternative cell permeability technique for applications in biomedical engineering, cell drug delivery and gene therapy.
A new sterilization technique of bovine pericardial biomaterial using microwave radiation
Publisher: Mary Ann Liebert Inc
Date: 09-2009
DOI: 10.1089/TEN.TEC.2008.0350
Abstract: Bioprosthetic valves created from chemically treated natural tissues such as bovine pericardial biomaterial are used as heart valve scaffolds. Methods currently available for sterilization of biomaterial for transplantation include the application of gamma radiation and chemical sterilants. These techniques, however, can be problematic because they can be expensive and lead to a reduction in tissue integrity. Therefore, improved techniques are needed that are cost effective and do not disrupt the physical properties, functionality, and lifespan of the valvular leaflets. This study examined a novel technique using nonthermal microwave radiation that could lead to the inactivation of bacteria in bovine pericardial biomaterial without compromising valve durability. Two common pathogenic species of bacteria, Escherichia coli and Staphylococcus aureus, were used as test microorganisms. Optimized microwave parameters were used to determine whether inactivation of pathogenic bacteria from bovine pericardium could be achieved. In addition, the effect of microwave sterilization on tissue integrity was examined. The mechanical properties (assessed using dynamic mechanical analysis) and tensile strength testing (using a Universal Tensile Tester) as well as thermal analysis (using thermogravimetric analysis and differential scanning calorimetry) indicated that microwave sterilization did not compromise the functionality of bovine pericardial biomaterial. Scanning electron microscopy imaging and cytotoxicity testing also confirmed that the structure and biocompatibility of transplant biomaterial remained unaltered after the sterilization process. Results from the application of this new microwave (MW) sterilization technique to bovine pericardium showed that near-complete inactivation of the contaminant bacteria was achieved. It is concluded that nonthermal inactivation of pathogenic bacteria from bovine pericardial biomaterial could be achieved using microwave radiation.
Antibacterial surfaces: The quest for a new generation of biomaterials
Publisher: Elsevier BV
Date: 05-2013
DOI: 10.1016/J.TIBTECH.2013.01.017
Abstract: In this review we attempt to clarify the notion of what is meant by the term antibacterial surfaces and categorise the approaches that are commonly used in the design of antibacterial surfaces. Application of surface coatings and the modification of the surface chemistry of substrata are generally considered to be a chemical approach to surface modification (as are surface polymerisation, functionalisation, and derivatisation), whereas, modification of the surface architecture of a substrate can be considered a physical approach. Here, the antifouling and bactericidal effects of antibacterial surfaces are briefly discussed. Finally, several recent efforts to design a new generation of antibacterial surfaces, which are based on mimicking the surface nanotopography of natural surfaces, are considered.
Bacterial attachment on sub-nanometrically smooth titanium substrata
Publisher: Informa UK Limited
Date: 17-01-2013
DOI: 10.1080/08927014.2012.757697
Abstract: Despite the volume of work that has been conducted on the topic, the role of surface topography in mediating bacterial cell adhesion is not well understood. The primary reason for this lack of understanding is the relatively limited extent of topographical characterisation employed in many studies. In the present study, the topographies of three sub-nanometrically smooth titanium (Ti) surfaces were comprehensively characterised, using nine in idual parameters that together describe the height, shape and distribution of their surface features. This topographical analysis was then correlated with the adhesion behaviour of the pathogenic bacteria Staphylococcus aureus and Pseudomonas aeruginosa, in an effort to understand the role played by each aspect of surface architecture in influencing bacterial attachment. While P. aeruginosa was largely unable to adhere to any of the three sub-nanometrically smooth Ti surfaces, the extent of S. aureus cell attachment was found to be greater on surfaces with higher average, RMS and maximum roughness and higher surface areas. The cells also attached in greater numbers to surfaces that had shorter autocorrelation lengths and skewness values that approached zero, indicating a preference for less ordered surfaces with peak heights and valley depths evenly distributed around the mean plane. Across the sub-nanometrically smooth range of surfaces tested, it was shown that S. aureus more easily attached to surfaces with larger features that were evenly distributed between peaks and valleys, with higher levels of randomness. This study demonstrated that the traditionally employed litudinal roughness parameters are not the only determinants of bacterial adhesion, and that spatial parameters can also be used to predict the extent of attachment.
Dual role of outer epicuticular lipids in determining the wettability of dragonfly wings
Publisher: Elsevier BV
Date: 06-2013
DOI: 10.1016/J.COLSURFB.2013.01.042
Abstract: Numerous natural surfaces possess superhydrophobicity and self-cleaning properties that would be extremely beneficial when applied in industry. Dragonfly wings are one ex le of such surfaces, and while their general surface structure is known, their precise chemical composition is not. Here, the epicuticular lipids of dragonfly wing membranes were characterized to investigate their significance in contributing to self-cleaning and superhydrophobic properties. After just 10s of lipid extraction using chloroform, the water contact angles exhibited by the wings decreased below the accepted threshold for superhydrophobicity (150°). Infrared spectra collected at the Australian Synchrotron contained characteristic absorption bands of amide, ester and aliphatic hydrocarbons moieties on the wing surfaces, the latter of which was decreased post-extraction with chloroform. GC-MS data analysis revealed that the epicuticular wax components were dominated by n-alkanes with even-numbered carbons, especially n-hexacosane, and palmitic acid. SEM and AFM data analysis conducted on the untreated and chloroform-extracted wing surfaces demonstrated that surface topography changed after extraction the surface nanostructure was progressively lost with extended extraction times. The data presented here indicate that epicuticular lipids contribute not only to self-cleaning and superhydrophobic properties through their inherent hydrophobic nature, but also by forming the physical structure of the wing surface. This knowledge will be extremely valuable for reconstruction of dragonfly wing structures as a biomimetic template.
Surface topographical factors influencing bacterial attachment
Publisher: Elsevier BV
Date: 11-2012
DOI: 10.1016/J.CIS.2012.06.015
Abstract: Substratum surface roughness is known to be one of the key factors in determining the extent of bacterial colonization. Understanding the way by which the substratum topography, especially at the nanoscale, mediates bacterial attachment remains ambiguous at best, despite the volume of work available on the topic. This is because the vast majority of bacterial attachment studies do not perform comprehensive topographical characterization analyses, and typically consider roughness parameters that describe only one aspect of the surface topography. The most commonly reported surface roughness parameters are average and root mean square (RMS) roughness (R(a) and R(q) respectively), which are both measures of the typical height variation of the surface. They offer no insights into the spatial distribution or shape of the surface features. Here, a brief overview of the current state of research on topography-mediated bacterial adhesion is presented, as well as an outline of the suite of roughness characterization parameters that are available for the comprehensive description of the surface architecture of a substratum. Finally, a set of topographical parameters is proposed as a new standard for surface roughness characterization in bacterial adhesion studies to improve the likelihood of identifying direct relationships between substratum topography and the extent of bacterial adhesion.
Adsorption of aqueous heavy metals onto carbonaceous substrates
Publisher: Elsevier BV
Date: 09-1999
Molecular Organization of the Nanoscale Surface Structures of the Dragonfly Hemianax papuensis Wing Epicuticle
Publisher: Public Library of Science (PLoS)
Date: 09-07-2013
Roughness parameters for standard description of surface nanoarchitecture
Publisher: Wiley
Date: 13-02-2012
DOI: 10.1002/SCA.21002
Abstract: The nanoarchitecture and surface roughness of metallic thin films prepared by magnetron sputtering were analyzed to determine the topographical statistics that give the optimum description of their nanoarchitechture. Nanoscale topographical profiles were generated by performing atomic force microscopy (AFM) scans of 1 μm × 1 μm areas of titanium and silver films of three different thicknesses (3 nm, 12 nm, and 150 nm). Of the titanium films, the 150-nm film had the highest average roughness (R(a) = 2.63 nm), more than four times that of the 3-nm and 12-nm titanium films. When silver films were coated on top of 150-nm titanium films, the average roughness increased further the 3-nm (R(a) = 4.96 nm) and 150-nm (R(a) = 4.65 nm) silver films average roughnesses were approximately twice that of the 150-nm titanium film. For topographical analysis, seven statistical parameters were calculated. These parameters included commonly used roughness measurements, as well as some less commonly used measurements, in order to determine which combination of parameters gave the best overall description of the nanoarchitecture of the films presented. Skewness (R(skw)), surface area increase (R(sa)), and peak counts (R(pc)) provided the best description of horizontal surface dimensions, and in conjunction with vertical descriptors R(a) and R(q) gave the best characterization of surface architecture. The five roughness parameters R(a), R(q), R(skw), R(sa), and R(pc) are proposed as a new standard for describing surface nanoarchitecture.
Celeribacter neptunius gen. nov., sp. nov., a new member of the class Alphaproteobacteria
Publisher: Microbiology Society
Date: 07-2010
Abstract: A whitish Gram-negative, motile, aerobic bacterium, designated strain H 14 T , was isolated from seawater collected at St Kilda beach in Port Phillip Bay, Melbourne, Australia. Analysis of 16S rRNA gene sequences revealed that the organism belonged to the Roseobacter lineage of the class Alphaproteobacteria , forming a distinct evolutionary lineage at the genus level. Strain H 14 T was distantly related to the genera Nautella , Ruegeria and Pseudoruegeria (family Rhodobacteraceae ). Strain H 14 T was unable to degrade gelatin, casein, chitin, agar and starch, did not produce any carotenoids, did not possess bacteriochlorophyll a and had a limited ability to utilize carbon sources. Strain H 14 T grew with concentrations of 1–8 % (w/v) NaCl and over a temperature range of 5–35 °C. Phosphatidylglycerol was the major phospholipid (90 %) phosphatidylcholine (7.9 %) and phosphatidylethanolamine (2.0 %) were present in minor quantities. The predominant fatty acids were C 18 : 1 ω 7 c (82.4 %), C 18 : 1 ω 9 c (5.1 %) and C 18 : 0 (3.8 %). The DNA G+C composition for strain H 14 T was 59.1 mol%. Based on the results of physiological, biochemical, chemotaxonomic and phylogenetic investigations, a new genus, Celeribacter gen. nov., with the type species Celeribacter neptunius sp. nov. is proposed. The type strain of the type species is H 14 T (=KMM 6012 T =CIP 109922 T ).
Winogradskyella exilis sp. nov., isolated from the starfish Stellaster equestris, and emended description of the genus Winogradskyella
Publisher: Microbiology Society
Date: 07-2010
Abstract: A pale-yellowish-pigmented strain, 022-2-26 T , was isolated from a starfish, Stellaster equestris . Cells of strain 022-2-26 T were Gram-negative short rods that were chemo-organotrophic, alkalitolerant and mesophilic. The predominant menaquinone was MK-6. The major cellular fatty acids were iso-C 15 : 0 , iso-C 15 : 1 , C 15 : 0 , iso-C 15 : 0 2-OH and iso-C 17 : 0 3-OH (together representing 87 % of the total fatty acids). The DNA G+C content was 30.1 mol%. A 16S rRNA gene sequence of the isolate was determined and phylogenetic analyses revealed that strain 022-2-26 T formed a robust clade (neighbour-joining algorithm with a bootstrap value of 95 % and parsimony and maximum-likelihood algorithms) with type strains of species in the genus Winogradskyella . The closest phylogenetic neighbour of strain 022-2-26 T was Winogradskyella poriferorum UST030701-295 T (96 % 16S rRNA gene sequence similarity 59 differences between sequences). On the basis of the phenotypic and chemotaxonomic characteristics and the phylogenetic evidence, it is proposed that strain 022-2-26 T represents a novel species, Winogradskyella exilis sp. nov. The type strain is 022-2-26 T (=KMM 6013 T =CIP 109976 T ).
Pseudomonas brassicacearum subsp. neoaurantiaca subsp. nov., orange-pigmented bacteria isolated from soil and the rhizosphere of agricultural plants
Publisher: Microbiology Society
Date: 21-07-2009
Abstract: A large group of 38 strains of saprophytic bacteria was isolated from soil and the rhizosphere of agricultural plants. The novel organisms were Gram-negative, aerobic, rod-shaped bacteria that produced a green fluorescent pigment, a red-orange diffusible pigment and a complex mixture of phloroglucinol derivates with antimicrobial activity. The latter have not been found in other bacteria, but are peculiar to ferns. The bacteria were vigorous denitrifiers that synthesized levan from sucrose and liquefied gelatin, but were found not to degrade aesculin, starch, agar, Tween 80 or DNA. Bacterial growth was found to occur at 4 degrees C but not at 40 degrees C. The predominant cellular fatty acids were 16 : 0, 16 : 1(n-7), 18 : 1(n-7) and 17 : 0 cyclo. The G+C content of the novel bacteria was 61.0-62.9 mol%. 16S rRNA gene sequence analysis indicated that the representative strain CIP 109457(T) had a clear affiliation with Pseudomonas sensu stricto groups, with the nearest relatives being Pseudomonas brassicacearum, P. thivervalensis, P. corrugata, P. mediterranea and P. kilonensis. DNA-DNA hybridization experiments showed that the group of isolated strains exhibited high levels of genetic relatedness (81-100 %), confirming that they are representatives of the same species. At the same time, they bound at low levels (4-46 %) with DNA of the type strains of their nearest relatives with the exception of P. brassicacearum DNA binding of 90 % with the DNA of P. brassicacearum CIP 107059(T) suggested that the bacteria studied belong to this species. Analysis of taxonomic data indicated that the group of novel bacteria maintain a distinct phenotypic profile, allowing the description of novel subspecies within P. brassicacearum, for which the following names are proposed: Pseudomonas brassicacearum subsp. brassicacearum subsp. nov. (type strain DBK11(T) =CFBP 11706(T) =CIP 107059(T) =DSM 13227(T) =JCM 11938(T)) and Pseudomonas brassicacearum subsp. neoaurantiaca subsp. nov., with the type strain CIP 109457(T) (=ATCC 49054(T) =IMV 387(T) =VKM B-1524(T)).
Acylated flavonoid tetraglycoside from Planchonia careya leaves
Publisher: Elsevier BV
Date: 08-2008
Self-organised nanoarchitecture of titanium surfaces influences the attachment of Staphylococcus aureus and Pseudomonas aeruginosa bacteria
Publisher: Springer Science and Business Media LLC
Date: 17-04-2015
DOI: 10.1007/S00253-015-6572-7
Abstract: The surface nanotopography and architecture of medical implant devices are important factors that can control the extent of bacterial attachment. The ability to prevent bacterial attachment substantially reduces the possibility of a patient receiving an implant contracting an implant-borne infection. We now demonstrated that two bacterial strains, Staphylococcus aureus and Pseudomonas aeruginosa, exhibited different attachment affinities towards two types of molecularly smooth titanium surfaces each possessing a different nanoarchitecture. It was found that the attachment of S. aureus cells was not restricted on surfaces that had an average roughness (S a) less than 0.5 nm. In contrast, P. aeruginosa cells were found to be unable to colonise surfaces possessing an average roughness below 1 nm, unless sharp nanoprotrusions of approximately 20 nm in size and spaced 35.0 nm apart were present. It is postulated that the enhanced attachment of P. aeruginosa onto the surfaces possessing these nanoprotrusions was facilitated by the ability of the cell membrane to stretch over the tips of the nanoprotrusions as confirmed through computer simulation, together with a concomitant increase in the level of extracellular polymeric substance (EPS) being produced by the bacterial cells.
Do bacteria differentiate between degrees of nanoscale surface roughness?
Publisher: Wiley
Date: 26-08-2011
Abstract: Whereas the employment of nanotechnology in electronics and optics engineering is relatively well established, the use of nanostructured materials in medicine and biology is undoubtedly novel. Certain nanoscale surface phenomena are being exploited to promote or prevent the attachment of living cells. However, as yet, it has not been possible to develop methods that completely prevent cells from attaching to solid surfaces, since the mechanisms by which living cells interact with the nanoscale surface characteristics of these substrates are still poorly understood. Recently, novel and advanced surface characterisation techniques have been developed that allow the precise molecular and atomic scale characterisation of both living cells and the solid surfaces to which they attach. Given this additional capability, it may now be possible to define boundaries, or minimum dimensions, at which a surface feature can exert influence over an attaching living organism.This review explores the current research on the interaction of living cells with both native and nanostructured surfaces, and the role that these surface properties play in the different stages of cell attachment.
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