ORCID Profile
0000-0002-2957-1347
Current Organisations
University of Technology Sydney
,
University of New South Wales
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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 | Environmental Nanotechnology | Nanotoxicology, Health and Safety | Composite Materials | Nanotechnology | Biomaterials
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in Engineering | Environmental Health | Health Protection and/or Disaster Response | Skeletal system and disorders (incl. arthritis) | Organs, diseases and abnormal conditions not elsewhere classified |
Related Links
Publications
Anti-angiogenic activity of heparin functionalised cerium oxide nanoparticles
Publisher: Elsevier BV
Date: 11-2013
DOI: 10.1016/J.BIOMATERIALS.2013.07.083
Abstract: Cerium oxide nanoparticles (nanoceria) are widely reported to be non-cytotoxic and modulate intracellular reactive oxygen species (ROS). In this study, nanoceria (dxRD = 12 nm) were functionalised with either 130 or 880 molecules of unfractionated heparin using the organosilane linker, 3-aminopropyltriethoxysilane. Nanoceria with a low level of heparin functionalisation were found to scavenge intracellular ROS to the same extent as unfunctionalised nanoceria and significantly more than cells exposed to medium only. In contrast, nanoceria with the highest level of heparin functionalisation were not as effective at scavenging intracellular ROS. Nanoceria were localised predominantly in the cytoplasm, while heparin-nanoceria were localised in both the cytoplasm and lysosomes. Together these data demonstrated that the level of nanoceria surface functionalisation with heparin determined the intracellular localisation and ROS scavenging ability of these particles. Additionally, heparin-nanoceria were effective in reducing endothelial cell proliferation indicating that they may find application in the control of angiogenesis in cancer in the future.
Evolution of biofilm-forming pathogenic bacteria in the presence of nanoparticles and antibiotic: adaptation phenomena and cross-resistance
Publisher: Springer Science and Business Media LLC
Date: 27-09-2021
DOI: 10.1186/S12951-021-01027-8
Abstract: Treatment of bacterial biofilms are difficult and in many cases, expensive. Bacterial biofilms are naturally more resilient to antimicrobial agents than their free-living planktonic counterparts, rendering the community growth harder to control. The present work described the risks of long-term use of an important alternative antimicrobial, silver nanoparticles (NAg), for the first time, on the dominant mode of bacterial growth. NAg could inhibit the formation as well as eradicating an already grown biofilm of Pseudomonas aeruginosa , a pathogen notorious for its resilience to antibiotics. The biofilm-forming bacterium however, evolved a reduced sensitivity to the nanoparticle. Evidence suggests that survival is linked to the development of persister cells within the population. A similar adaptation was also seen upon prolonged exposures to ionic silver (Ag + ). The persister population resumed normal growth after subsequent passage in the absence of silver, highlighting the potential risks of recurrent infections with long-term NAg (and Ag + ) treatments of biofilm growth. The present study further observed a potential silver/antibiotic cross-resistance, whereby NAg (as well as Ag + ) could not eradicate an already growing gentamicin-resistant P. aeruginosa biofilm. The phenomena is thought to result from the hindered biofilm penetration of the silver species. In contrast, both silver formulations inhibited biofilm formation of the resistant strain, presenting a promising avenue for the control of biofilm-forming antibiotic-resistant bacteria. The findings signify the importance to study the nanoparticle adaptation phenomena in the biofilm mode of bacterial growth, which are apparently unique to those already reported with the planktonic growth counterparts. This work sets the foundation for future studies in other globally significant bacterial pathogens when present as biofilms. Scientifically based strategies for management of pathogenic growth is necessary, particularly in this era of increasing antibiotic resistance.
Yeast pyruvate decarboxylases: variation in biocatalytic characteristics for (R)-phenylacetylcarbinol production.
Publisher: Oxford University Press (OUP)
Date: 2007
DOI: 10.1111/J.1567-1364.2006.00138.X
Abstract: Based on previous studies, Candida utilis pyruvate decarboxylase (PDC) proved to be a stable and high productivity enzyme for the production (R)-phenylacetylcarbinol (PAC), a pharmaceutical precursor. However, a portion of the substrate pyruvate was lost to by-product formation. To identify a source of PDC which might overcome this problem, strains of four yeasts -- C. utilis, Candida tropicalis, Saccharomyces cerevisiae and Kluyveromyces marxianus -- were investigated for their PDC biocatalytic properties. Biotransformations were conducted with benzaldehyde and pyruvate as substrates and three experimental systems were employed (in the order of increasing benzaldehyde concentrations): (I) aqueous (soluble benzaldehyde), (II) aqueous/benzaldehyde emulsion, and (III) aqueous/octanol-benzaldehyde emulsion. Although C. utilis PDC resulted in the highest concentrations of PAC and was the most stable enzyme, C. tropicalis PDC was associated with the lowest acetoin formation. For ex le, in system (III) the ratio of PAC over acetoin was 35 g g(-1) for C. tropicalis PDC and 9.2 g g(-1) for C. utilis PDC. The study thereby opens up the potential to design a PDC with both high productivity and high yield characteristics.
Nanoscale Titanium Surface Engineering via Low-Temperature Hydrothermal Etching for Enhanced Antimicrobial Properties
Publisher: American Chemical Society (ACS)
Date: 22-09-2023
Cytotoxic origin of copper(II) oxide nanoparticles: Comparative studies with micron-sized particles, leachate, and metal salts
Publisher: American Chemical Society (ACS)
Date: 12-08-2011
DOI: 10.1021/NN2020248
Abstract: The work investigates the source of toxicity of copper oxide nanoparticles (CuO NPs) with respect to its leaching characteristic and speciation. Complexation-mediated leaching of CuO NPs by amino acids was identified as the source of toxicity toward Escherichia coli, the model microorganism used in the current study. The leached copper-peptide complex induces a multiple-fold increase in intracellular reactive oxygen species generation and reduces the fractions of viable cells, resulting in the overall inhibition of biomass growth. The cytotoxicity of the complex leachate is however different from that of equivalent soluble copper salts (nitrates and sulfates). A pH-dependent copper speciation during the addition of copper salts gives rise to uncoordinated copper ions, which in turn result in greater toxicity and cell lysis, the latter of which was not observed for CuO NPs even at comparable pH. Since leaching did not occur with micrometer-sized CuO, no cytotoxicty effect was observed, thus highlighting the prominence of materials toxicity at the nanoscale.
Nanoparticle-protein corona complexes govern the biological fates and functions of nanoparticles
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3TB21526A
Coal-packed methane biofilter for mitigation of green house gas emissions from coal mine ventilation air.
Publisher: Public Library of Science (PLoS)
Date: 17-04-2014
The impact of silver nanoparticles on microbial communities and antibiotic resistance determinants in the environment
Publisher: Elsevier BV
Date: 2022
DOI: 10.1016/J.ENVPOL.2021.118506
Abstract: Nanosilver (NAg) is currently one of the major alternative antimicrobials to control microorganisms. With its broad-spectrum efficacy and lucrative commercial values, NAg has been used in medical devices and increasingly, in consumer products and appliances. This widespread use has inevitably led to the release and accumulation of the nanoparticle in water and sediment, in soil and even, wastewater treatment plants (WWTPs). This Article describes the physical and chemical transformations of NAg as well as the impact of the nanoparticle on microbial communities in different environmental settings how the nanoparticle shifts not only the ersity and abundance of microbes, including those that are important in nitrogen cycles and decomposition of organic matters, but also their associated genes and in turn, the key metabolic processes. Current findings on the microbiological activity of the leached soluble silver, solid silver particulates and their respective transformed products, which underpin the mechanism of the nanoparticle toxicity in environmental microbes, is critically discussed. The Article also addresses the emerging evidence of silver-driven co-selection of antibiotic resistance determinants. The mechanism has been linked to the increasing pools of many antibiotic resistance genes already detected in s les from different environmental settings, which could ultimately find their ways to animals and human. The realized ecological impact of NAg calls for more judicial use of the nanoparticle. The generated knowledge can inform strategies for a better 'risks versus benefits' assessment of NAg applications, including the disposal stage.
Improved (R)-phenylacetylcarbinol production with Candida utilis pyruvate decarboxylase at decreased organic to aqueous phase volume ratios.
Publisher: Springer Science and Business Media LLC
Date: 18-09-2008
DOI: 10.1007/S10529-007-9525-0
Abstract: The effect of decreasing the organic (octanol) to aqueous phase volume ratio was evaluated in a two-phase enzymatic process for (R)-phenylacetylcarbinol (PAC) production. Decreasing the ratio from 1:1 to 0.43:1 at 4 degrees C increased PAC in the organic phase from 112 g/l to 183 g/l with a 10% improvement in overall productivity. Interestingly, the rate of enzyme (pyruvate decarboxylase) activity loss was unaffected by the reduced phase ratio over the reaction period (48 h). At 20 degrees C and 0.43:1 phase ratio the organic phase PAC concentration increased to 212 g/l and the overall productivity increased by 30% although the PAC yield (based on pyruvate) declined by about 10% due to greater byproduct acetoin formation at the higher temperature. Product recovery in such a system is facilitated both by the higher PAC concentration and the reduced organic phase volume.
Cellular uptake and reactive oxygen species modulation of cerium oxide nanoparticles in human monocyte cell line U937
Publisher: Elsevier BV
Date: 11-2012
DOI: 10.1016/J.BIOMATERIALS.2012.07.024
Abstract: Cerium oxide nanoparticles (nanoceria) are promising materials for intracellular oxygen free radical scavenging providing a potential therapy for reactive oxygen species (ROS)-mediated inflammatory processes. In this study rhombohedral-shaped nanoceria were synthesized by flame spray pyrolysis with tuneable particle diameters between 3 and 94 nm by changing the liquid precursor flow rate. Monocytes and macrophages are major players in inflammatory processes as their production of ROS species has important downstream effects on cell signalling. Therefore, this study examined the ability of the nanoceria to be internalised by the human monocytic cell line, U937, and scavenge intracellular ROS. U937 cells activated in the presence of phorbol 12-myristate 13-acetate (PMA) were found to be more responsive to the nanoceria than U937 cells, which may not be surprising given the role of monocyte/macrophages in phagocytosing foreign material. The smaller particles were found to contain more crystal lattice defects with which to scavenge ROS, however a greater proportion of both the U937 and activated U937 cell populations responded to the larger particles. Hence all nanoceria particle sizes examined in this study were equally effective in scavenging intracellular ROS.
Development of Nanoparticle Adaptation Phenomena in Acinetobacter baumannii: Physiological Change and Defense Response
Publisher: American Society for Microbiology
Date: 14-02-2023
DOI: 10.1128/SPECTRUM.02857-22
Abstract: Several recent studies have reported on the development of bacterial resistance to broad-spectrum antimicrobial silver nanoparticles (nanosilver NAg). NAg is currently one of the most important alternative antimicrobial agents.
Hydroxyl Radical Generating Monovalent Copper Particles for Antimicrobial Application
Publisher: Hindawi Limited
Date: 25-04-2023
DOI: 10.1155/2023/8812824
Abstract: The antimicrobial properties of copper are well-known but maintaining a low oxidation state of Cu in particles is difficult. Herein, antimicrobial CuxP particles were synthesized through phosphorization of Cu(OH)2, to lock copper in its monovalent state (as Cu3P). We found that the phosphorization could be achieved at temperatures as low as 200°C, with stable surface presence of Cu(I) on the resulting CuxP particles. Cu(I) can act as a one-electron reducing agent for molecular oxygen, to generate the highly reactive hydroxyl radical. In this study, CuxP displayed antibacterial activities on the Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli, with minimum inhibitory concentrations of 32 mg/L for the highest temperature particles (350°C) on both model bacteria. The evident membrane damage is consistent with the intended hydroxyl radical bacterial targeting mechanism. Low-temperature CuxP, although exhibiting lower antibacterial efficacies than those of the higher temperature variant, still showed competitive growth inhibiting activities when compared to other reported antimicrobial copper-based particles. The present work showcases advancements in particle technology that can lead to the development of a more robust antimicrobial agent, presenting a potent additive for self-disinfection applications.
Induced adaptation of Bacillus sp. to antimicrobial nanosilver
Publisher: Wiley
Date: 29-04-2013
Abstract: The natural ability of Bacillus sp. to adapt to nanosilver cytotoxicity upon prolonged exposure is reported for the first time. The combined adaptive effects of nanosilver resistance and enhanced growth are induced under various intensities of nanosilver-stimulated cellular oxidative stress, ranging from only minimal cellular redox imbalance to the lethal levels of cellular ROS stimulation. An important implication of the present work is that such adaptive effects lead to the ultimate domination of nanosilver-resistant Bacillus sp. in the microbiota, to which nanosilver cytotoxicity is continuously applied.
Cl415, a carbapenem-resistant Acinetobacter baumannii isolate containing four AbaR4 and a new variant of AbGRI2, represents a novel global clone 2 strain
Publisher: Oxford University Press (OUP)
Date: 06-11-2021
DOI: 10.1093/JAC/DKAB399
Abstract: To determine the genetic context of genes conferring antibiotic resistance on the carbapenem-resistant Acinetobacter baumannii Cl415, recovered in 2017 at El Youssef Hospital Centre in Akkar Governorate, North Lebanon. Antibiotic resistance phenotype for 22 antibiotics was determined using disc diffusion or MIC determination. The whole-genome sequence of Cl415 was determined using a combination of the Illumina MiSeq and Oxford Nanopore (MinION) platforms. Complete genome was assembled using Unicycler and antibiotic resistance determinants and ISs were identified using ResFinder and ISFinder, respectively. Cl415 is a global clone 2 (GC2) strain and belongs to the most common STs of this clone, ST2IP and ST218OX. Cl415 is resistant to several antibiotics, including aminoglycosides and carbapenems to a high level. Genomic analysis of Cl415 revealed that it carries four chromosomal AbaR4 copies. One copy was found in the comM gene replacing the AbGRI1 island. Cl415 also contains a novel variant of AbGRI2, herein called AbGRI2-15, carrying only the blaTEM and aphA1 resistance genes. Cl415 belongs to a subclade of GC2 strains that appear to have erged recently with a wide geographical distribution. The resistance gene complement of Cl415 was found in the chromosome with four oxa23 located in AbaR4 copies and the remaining genes in a novel variant of the AbGRI2 resistance island. Cl415 was isolated in Lebanon, but phylogenetic analysis suggests that Cl415 represents a new lineage with global distribution within GC2.
Systematic and Bibliometric Analysis of Magnetite Nanoparticles and Their Applications in (Biomedical) Research
Publisher: Wiley
Date: 14-09-2022
Abstract: Recent reports show air pollutant magnetite nanoparticles (MNPs) in the brains of people with Alzheimer's disease (AD). Considering various field applications of MNPs because of developments in nanotechnology, the aim of this study is to identify major trends and data gaps in research on magnetite to allow for relevant environmental and health risk assessment. Herein, a bibliometric and systematic analysis of the published magnetite literature ( n = 31 567) between 1990 to 2020 is completed. Following appraisal, publications ( n = 244) are grouped into four time periods with the main research theme identified for each as 1990–1997 “oxides,” 1998–2005 “ferric oxide,” 2006–2013 “pathology,” and 2014–2020 “animal model.” Magnetite formation and catalytic activity dominate the first two time periods, with the last two focusing on the exploitation of nanoparticle engineering. Japan and China have the highest number of citations for articles published. Longitudinal analysis indicates that magnetite research for the past 30 years shifted from environmental and industrial applications, to biomedical and its potential toxic effects. Therefore, whilst this study presents the research profile of different countries, the development in research on MNPs, it also reveals that further studies on the effects of MNPs on human health is much needed.
Zinc oxide nanoparticles induce cell filamentation in escherichia coli
Publisher: Wiley
Date: 28-02-2013
In vitro coronal protein signatures and biological impact of silver nanoparticles synthesized with different natural polymers as capping agents
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D0NA01013H
Abstract: Biopolymer-capped silver nanoparticle synthesis. Compositional and stability analysis of synthesised particles. Proteomic analysis of particles following serum exposure. In vitro hemolytic assays. Organ distribution following administration in mice.
The effect of common bacterial growth media on zinc oxide thin films: Identification of reaction products and implications for the toxicology of ZnO
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3RA46177G
Challenges to developing methane biofiltration for coal mine ventilation air: A review
Publisher: Springer Science and Business Media LLC
Date: 09-05-2013
Submicron and nano formulations of titanium dioxide and zinc oxide stimulate unique cellular toxicological responses in the green microalga Chlamydomonas reinhardtii
Publisher: Elsevier BV
Date: 09-2013
DOI: 10.1016/J.JHAZMAT.2013.06.067
Abstract: The work investigates the eco-cytoxicity of submicron and nano TiO₂ and ZnO, arising from the unique interactions of freshwater microalga Chlamydomonas reinhardtii to soluble and undissolved components of the metal oxides. In a freshwater medium, submicron and nano TiO₂ exist as suspended aggregates with no-observable leaching. Submicron and nano ZnO undergo comparable concentration-dependent fractional leaching, and exist as dissolved zinc and aggregates of undissolved ZnO. Cellular internalisation of solid TiO₂ stimulates cellular ROS generation as an early stress response. The cellular redox imbalance was observed for both submicron and nano TiO₂ exposure, despite exhibiting benign effects on the alga proliferation (8-day EC50>100 mg TiO₂/L). Parallel exposure of C. reinhardtii to submicron and nano ZnO saw cellular uptake of both the leached zinc and solid ZnO and resulting in inhibition of the alga growth (8-day EC50≥0.01 mg ZnO/L). Despite the sensitivity, no zinc-induced cellular ROS generation was detected, even at 100 mg ZnO/L exposure. Taken together, the observations confront the generally accepted paradigm of cellular oxidative stress-mediated cytotoxicity of particles. The knowledge of speciation of particles and the corresponding stimulation of unique cellular responses and cytotoxicity is vital for assessment of the environmental implications of these materials.
Nanosilver Targets the Bacterial Cell Envelope: The Link with Generation of Reactive Oxygen Radicals
Publisher: American Chemical Society (ACS)
Date: 13-01-2020
Abstract: The work describes the interactions of nanosilver (NAg) with bacterial cell envelope components at a molecular level and how this associates with the reactive oxygen species (ROS)-mediated toxicity of the nanoparticle. Major structural changes were detected in cell envelope biomolecules as a result of damages in functional moieties, such as the saccharides, amides, and phosphodiesters. NAg exposure disintegrates the glycan backbone in the major cell wall component peptidoglycan, causes complete breakdown of lipoteichoic acid, and disrupts the phosphate-amine and fatty acid groups in phosphatidylethanolamine, a membrane phospholipid. Consistent with the oxidative attacks, we propose that the observed cell envelope damages are inflicted, at least in part, by the reactive oxygen radicals being generated by the nanoparticle during its leaching process, abiotically, without cells. The cell envelope targeting, especially those on the inner membrane phospholipid, is likely to then trigger the rapid generation of lethal levels of cellular superoxide (O
Heritable nanosilver resistance in priority pathogen: a unique genetic adaptation and comparison with ionic silver and antibiotics
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/C9NR08424J
Abstract: A priority pathogen is capable to evolve stable resistance characteristics that still manifest after discontinuation of the nanosilver exposure.
Copper Complex in Poly(vinyl chloride) as a Nitric Oxide-Generating Catalyst for the Control of Nitrifying Bacterial Biofilms
Publisher: American Chemical Society (ACS)
Date: 06-10-2015
Abstract: In this study, catalytic generation of nitric oxide by a copper(II) complex embedded within a poly(vinyl chloride) matrix in the presence of nitrite (source of nitric oxide) and ascorbic acid (reducing agent) was shown to effectively control the formation and dispersion of nitrifying bacteria biofilms. Amperometric measurements indicated increased and prolonged generation of nitric oxide with the addition of the copper complex when compared to that with nitrite and ascorbic acid alone. The effectiveness of the copper complex-nitrite-ascorbic acid system for biofilm control was quantified using protein analysis, which showed enhanced biofilm suppression when the copper complex was used in comparison to that with nitrite and ascorbic acid treatment alone. Confocal laser scanning microscopy (CLSM) and LIVE/DEAD staining revealed a reduction in cell surface coverage without a loss of viability with the copper complex and up to 5 mM of nitrite and ascorbic acid, suggesting that the nitric oxide generated from the system inhibits proliferation of the cells on surfaces. Induction of nitric oxide production by the copper complex system also triggered the dispersal of pre-established biofilms. However, the addition of a high concentration of nitrite and ascorbic acid to a pre-established biofilm induced bacterial membrane damage and strongly decreased the metabolic activity of planktonic and biofilm cells, as revealed by CLSM with LIVE/DEAD staining and intracellular adenosine triphosphate measurements, respectively. This study highlights the utility of the catalytic generation of nitric oxide for the long-term suppression and removal of nitrifying bacterial biofilms.
Insights from a Bibliometrics-Based Analysis of Publishing and Research Trends on Cerium Oxide from 1990 to 2020
Publisher: MDPI AG
Date: 20-01-2023
DOI: 10.3390/IJMS24032048
Abstract: The purpose of this study is to evaluate the literature for research trends on cerium oxide from 1990 to 2020 and identify gaps in knowledge in the emerging application(s) of CeONP. Bibliometric methods were used to identify themes in database searches from PubMed, Scopus and Web of Science Core Collection using SWIFT-Review, VOSviewer and SciMAT software programs. A systematic review was completed on published cerium oxide literature extracted from the Scopus database (n = 17,115), identifying themes relevant to its industrial, environmental and biomedical applications. A total of 172 publications were included in the systematic analysis and categorized into four time periods with research themes identified “doping additives” (n = 5, 1990–1997), “catalysts” (n = 32, 1998–2005), “reactive oxygen species” (n = 66, 2006–2013) and “pathology” (n = 69, 2014–2020). China and the USA showed the highest number of citations and publications for cerium oxide research from 1990 to 2020. Longitudinal analysis showed CeONP has been extensively used for various applications due to its catalytic properties. In conclusion, this study showed the trend in research in CeONP over the past three decades with advancements in nanoparticle engineering like doping, and more recently surface modification or functionalization to further enhanced its antioxidant abilities. As a result of recent nanoparticle engineering developments, research into CeONP biological effects have highlighted its therapeutic potential for a range of human pathologies such as Alzheimer’s disease. Whilst research over the past three decades show the versatility of cerium oxide in industrial and environmental applications, there are still research opportunities to investigate the potential beneficial effects of CeONP in its application(s) on human health.
Microbiologically influenced stress corrosion cracking responsible for catastrophic failure of cable bolts
Publisher: Elsevier BV
Date: 2022
Oxygen-Vacancy Engineering of Cerium-Oxide Nanoparticles for Antioxidant Activity
Publisher: American Chemical Society (ACS)
Date: 30-05-2019
Reversible Antimicrobial Photoswitching in Nanosilver
Publisher: Wiley
Date: 29-01-2009
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