ORCID Profile
0000-0003-3297-3977
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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.
Macromolecular and Materials Chemistry | Macromolecular and Materials Chemistry not elsewhere classified | Chemical Characterisation of Materials | Cellular Interactions (incl. Adhesion, Matrix, Cell Wall) | Biomaterials |
Expanding Knowledge in the Chemical Sciences | Medical Instruments | Control of Pests, Diseases and Exotic Species in Fresh, Ground and Surface Water Environments | Food Safety
Publisher: Wiley
Date: 27-03-2023
Abstract: Plasma polymers from glycidol vapors are of interest for direct covalent grafting of molecules bearing amine or thiol groups. The question of whether pulsed plasma operation might lead to a higher surface density of epoxide groups and a higher density of grafted molecules is studied using the antifungal drug caspofungin. X‐ray photoelectron spectroscopy and Time of flight‐secondary ions mass spectrometry analysis followed by caspofungin grafting revealed that both continuous wave and pulsed plasmas led to surface epoxides but with higher densities upon pulsing. Investigations into stability suggested that glycidol plasma polymer coatings were still able to immobilize caspofungin after 2 years of storage, making them suitable for applications where grafting of molecules needs to be done immediately before usage of a device.
Publisher: Wiley
Date: 20-09-2022
Abstract: Plasma polymers have long been of interest as thin film coatings on biomedical devices and products, to generate desirable surface properties for favorable bio‐interfacial interactions. Plasma polymers have also been used as platforms for the covalent immobilization of bioactive molecules. More recently, additional aspects have been investigated, such as selective prevention of adhesion of microbial pathogens, either via plasma polymers per se or including antimicrobial drugs. Plasma polymers have also been investigated for the release of silver ions and small organic molecules. Complementing low‐pressure plasma approaches, processes at atmospheric pressure have attracted interest recently, including for nano/biocomposite coatings. This contribution reviews the use of plasma polymers for intended biomedical applications, with a focus on more recent topic areas.
Publisher: American Chemical Society (ACS)
Date: 27-01-2012
DOI: 10.1021/LA204714P
Abstract: Surface density gradients of streptavidin (SAV) were created on solid surfaces and demonstrated functionality as a bioconjugation platform. The surface density of immobilized streptavidin steadily increased in one dimension from 0 to 235 ng cm(-2) over a distance of 10 mm. The density of coupled protein was controlled by its immobilization onto a polymer surface bearing a gradient of aldehyde group density, onto which SAV was covalently linked using spontaneous imine bond formation between surface aldehyde functional groups and primary amine groups on the protein. As a control, human serum albumin was immobilized in the same manner. The gradient density of aldehyde groups was created using a method of simultaneous plasma copolymerization of ethanol and propionaldehyde. Control over the surface density of aldehyde groups was achieved by manipulating the flow rates of these vapors while moving a mask across substrates during plasma discharge. Immobilized SAV was able to bind biotinylated probes, indicating that the protein retained its functionality after being immobilized. This plasma polymerization technique conveniently allows virtually any substrate to be equipped with tunable protein gradients and provides a widely applicable method for bioconjugation to study effects arising from controllable surface densities of proteins.
Publisher: American Vacuum Society
Date: 11-2020
DOI: 10.1116/6.0000511
Abstract: A drug-eluting coating applied onto biomedical devices and implants is an appropriate way to ensure that an inhibitory concentration of antimicrobial drugs is present at the device surface, thus preventing surface colonization and subsequent biofilm formation. In this study, a thin polymer coating was applied to materials, and it acted as a drug-delivery reservoir capable of surface delivery of the antifungal drug fluconazole to amounts up to 21 μg/cm2. The release kinetics into aqueous solution were quantified by UV spectroscopy and conformed to the Ritger–Peppas and Korsmeyer–Peppas model. Complementary microbiological assays were used to determine effectiveness against Candida albicans attachment and biofilm formation, and against the control heptylamine plasma polymer coating without drug loading, on which substantial fungal growth occurred. Fluconazole release led to marked antifungal activity in all assays, with log 1.6 reduction in CFUs/cm2. Cell viability assays and microscopy revealed that fungal cells attached to the fluconazole-loaded coating remained rounded and did not form hyphae and biofilm. Thus, in vitro screening results for fluconazole-releasing surface coatings showed efficacy in the prevention of the formation of Candida albicans biofilm.
Publisher: American Chemical Society (ACS)
Date: 13-10-2021
Abstract: This study demonstrates the ability of
Publisher: Wiley
Date: 11-2022
Publisher: Elsevier BV
Date: 2018
DOI: 10.1016/J.BIOTECHADV.2017.11.010
Abstract: In recent years, increasing evidence has been collated on the contributions of fungal species, particularly Candida, to medical device infections. Fungal species can form biofilms by themselves or by participating in polymicrobial biofilms with bacteria. Thus, there is a clear need for effective preventative measures, such as thin coatings that can be applied onto medical devices to stop the attachment, proliferation, and formation of device-associated biofilms. However, fungi being eukaryotes, the challenge is greater than for bacterial infections because antifungal agents are often toxic towards eukaryotic host cells. Whilst there is extensive literature on antibacterial coatings, a far lesser body of literature exists on surfaces or coatings that prevent attachment and biofilm formation on medical devices by fungal pathogens. Here we review strategies for the design and fabrication of medical devices with antifungal surfaces. We also survey the microbiology literature on fundamental mechanisms by which fungi attach and spread on natural and synthetic surfaces. Research in this field requires close collaboration between biomaterials scientists, microbiologists and clinicians we consider progress in the molecular understanding of fungal recognition of, and attachment to, suitable surfaces, and of ensuing metabolic changes, to be essential for designing rational approaches towards effective antifungal coatings, rather than empirical trial of coatings.
Publisher: American Vacuum Society
Date: 29-08-2017
DOI: 10.1116/1.4986054
Abstract: There is a need for coatings for biomedical devices and implants that can prevent the attachment of fungal pathogens while allowing human cells and tissue to appose without cytotoxicity. Here, the authors study whether a poly(2-hydroxyethylmethacrylate) (PHEMA) coating can suppress attachment and biofilm formation by Candida albicans and whether caspofungin terminally attached to surface-tethered polymeric linkers can provide additional benefits. The multistep coating scheme first involved the plasma polymerization of ethanol, followed by the attachment of α-bromoisobutyryl bromide (BiBB) onto surface hydroxyl groups of the plasma polymer layer. Polymer chains were grafted using surface initiated activators regenerated by electron transfer atom transfer radical polymerization with 2-hydroxyethylmethacrylate, yielding PHEMA layers with a dry thickness of up to 89 nm in 2 h. Hydroxyl groups of PHEMA were oxidized to aldehydes using the Albright–Goldman reaction, and caspofungin was covalently immobilized onto them using reductive amination. While the PHEMA layer by itself reduced the growth of C. albicans biofilms by log 1.4, the addition of caspofungin resulted in a marked further reduction by & log units to below the threshold of the test. The authors have confirmed that the predominant mechanism of action is caused by antifungal drug molecules that are covalently attached to the surface, rather than out-diffusing from the coating. The authors confirm the selectivity of surface-attached caspofungin in eliminating fungal, not mammalian cells by showing no measurable toxicity toward the myeloid leukaemia suspension cell line KG-1a.
Publisher: IOP Publishing
Date: 07-2016
Publisher: Wiley
Date: 11-01-2016
Publisher: American Vacuum Society
Date: 27-11-2018
DOI: 10.1116/1.5050043
Abstract: Antimicrobial surface coatings that act through a contact-killing mechanism (not diffusive release) could offer many advantages to the design of medical device coatings that prevent microbial colonization and infections. However, as the authors show here, to prevent arriving at an incorrect conclusion about their mechanism of action, it is essential to employ thorough washing protocols validated by surface analytical data. Antimicrobial surface coatings were fabricated by covalently attaching polyene antifungal drugs to surface coatings. Thorough washing (often considered to be sufficient to remove noncovalently attached molecules) was used after immobilization and produced s les that showed a strong antifungal effect, with a log 6 reduction in Candida albicans colony forming units. However, when an additional washing step using surfactants and warmed solutions was used, more firmly adsorbed compounds were eluted from the surface as evidenced by XPS and ToF-SIMS, resulting in reduction and complete elimination of in vitro antifungal activity. Thus, polyene molecules covalently attached to surfaces appear not to have a contact-killing effect, probably because they fail to reach their membrane target. Without additional stringent washing and surface analysis, the initial favorable antimicrobial testing results could have been misinterpreted as evidencing activity of covalently grafted polyenes, while in reality activity arose from desorbing physisorbed molecules. To avoid unintentional confirmation bias, they suggest that binding and washing protocols be analytically verified by qualitative/quantitative instrumental methods, rather than relying on false assumptions of the rigors of washing/soaking protocols.
Publisher: American Vacuum Society
Date: 05-07-2013
Abstract: The ability to present signalling molecules within a low fouling 3D environment that mimics the extracellular matrix is an important goal for a range of biomedical applications, both in vitro and in vivo. Cell responses can be triggered by non-specific protein interactions occurring on the surface of a biomaterial, which is an undesirable process when studying specific receptor-ligand interactions. It is therefore useful to present specific ligands of interest to cell surface receptors in a 3D environment that minimizes non-specific interactions with biomolecules, such as proteins. In this study, surface-initiated atom transfer radical polymerization (SI-ATRP) of poly(ethylene glycol)-based monomers was carried out from the surface of electrospun fibers composed of a styrene/vinylbenzyl chloride copolymer. Surface initiated radical addition-fragmentation chain transfer (SI-RAFT) polymerisation was also carried out to generate bottle brush copolymer coatings consisting of poly(acrylic acid) and poly(acrylamide). These were grown from surface trithiocarbonate groups generated from the chloromethyl styrene moieties existing in the original synthesised polymer. XPS was used to characterise the surface composition of the fibers after grafting and after coupling with fluorine functional XPS labels. Bottle brush type coatings were able to be produced by ATRP which consisted of poly(ethylene glycol) methacrylate and a terminal alkyne-functionalised monomer. The ATRP coatings showed reduced non-specific protein adsorption, as a result of effective PEG incorporation and pendant alkynes groups existing as part of the brushes allowed for further conjugation of via azide-alkyne Huisgen 1,3-dipolar cycloaddition. In the case of RAFT, carboxylic acid moieties were effectively coupled to an amine label via amide bond formation. In each case XPS analysis demonstrated that covalent immobilisation had effectively taken place. Overall, the studies presented an effective platform for the preparation of 3D scaffolds which contain effective conjugation sites for attachment of specific bioactive signals of interest, as well as actively reducing non-specific protein interactions.
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4RA01892C
Abstract: Novel, highly chlorinated surface coatings were produced via a one-step plasma polymerization (pp) of 1,1,1-trichloroethane (TCE), exhibiting excellent antimicrobial properties against the vigorously biofilm-forming bacterium Staphylococcus epidermidis .
Publisher: IEEE
Date: 04-2013
Publisher: American Vacuum Society
Date: 14-10-2015
DOI: 10.1116/1.4933108
Abstract: Not only bacteria but also fungal pathogens, particularly Candida species, can lead to biofilm infections on biomedical devices. By covalent grafting of the antifungal drug caspofungin, which targets the fungal cell wall, onto solid biomaterials, a surface layer can be created that might be able to provide long-term protection against fungal biofilm formation. Plasma polymerization of propionaldehyde (propanal) was used to deposit a thin (∼20 nm) interfacial bonding layer bearing aldehyde surface groups that can react with amine groups of caspofungin to form covalent interfacial bonds for immobilization. Surface analyses by x-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry confirmed the intended grafting and uniformity of the coatings, and durability upon extended washing. Testing for fungal cell attachment and ensuing biofilm formation showed that caspofungin retained activity when covalently bound onto surfaces, disrupting colonizing Candida cells. Mammalian cytotoxicity studies using human primary fibroblasts indicated that the caspofungin-grafted surfaces were selective in eliminating fungal cells while allowing attachment and spreading of mammalian cells. These in vitro data suggest promise for use as antifungal coatings, for ex le, on catheters, and the use of a plasma polymer interlayer enables facile transfer of the coating method onto a wide variety of biomaterials and biomedical devices.
Publisher: Wiley
Date: 17-11-2014
Publisher: American Vacuum Society
Date: 11-2021
DOI: 10.1116/6.0001099
Abstract: There are many reports of antimicrobial coatings bearing immobilized active agents on surfaces however, strong analytical evidence is required to verify that the agents are indeed covalently attached to the surface. In the absence of such evidence, antimicrobial activity could result from a release of active agents. We report a detailed assessment of antifungal surface coatings prepared using covalent attachment chemistries, with the aim of establishing a set of instrumental and biological evidence required to convincingly demonstrate antimicrobial activity due to nonreleasing, surface active compounds and to exclude the alternate possibility of activity due to release. The strongest biological evidence initially supporting permanent antifungal activity was the demonstration of the ability to reuse s les in multiple, sequential pathogen challenges. However, additional supporting evidence from washing studies and instrumental analysis is also required to probe the possibility of gradual desorption of strongly physisorbed compounds versus covalently attached compounds. Potent antifungal surface coatings were prepared from approved pharmaceutical compounds from the echinocandin drug class (caspofungin, anidulafungin, and micafungin) and assessed by microbiological tests and instrumental methods. Carbonyl diimidazole linking chemistry enabled covalent attachment of caspofungin, anidulafungin, and micafungin to plasma polymer surfaces, with antifungal surface activity likely caused by molecular orientations that present the lipophilic tail toward interfacing fungal cells. This study demonstrates the instrumental and biological evidence required to convincingly ascertain activity due to nonreleasing, surface active compounds and summarize these as three criteria for assessing other reports on surface-immobilized antimicrobial compounds.
Publisher: American Vacuum Society
Date: 12-2015
DOI: 10.1116/1.4937464
Abstract: In the development of bioactive coatings on biomaterials, it is essential to characterize the successful fabrication and the uniformity of intended coatings by sensitive surface analytical techniques, so as to ensure reliable interpretation of observed biointerfacial responses. This can, however, be challenging when small bioactive molecules are grafted onto biomaterials surfaces at sub- and near-monolayer densities. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) provides the required sensitivity, but ion signals from small grafted molecules may still be dominated by fragment ions from the underlying polymer. In such cases, multivariate analysis provides valuable enhancement of spectral data, as illustrated here by ex les comprising the surface grafting of bioactive serrulatane molecules, the peptide GRGDSP, the oligonucleotide 15-thymidine, and the antifungal compound Amphotericin B. The authors also show how ToF-SIMS plus principal component analysis can distinguish between covalent grafting and physisorption of the antibiotics caspofungin and micafungin.
Publisher: Wiley
Date: 05-07-2018
Publisher: Elsevier BV
Date: 03-2014
DOI: 10.1016/J.BIOTECHADV.2013.10.015
Abstract: Microbial attachment onto biomedical devices and implants leads to biofilm formation and infection such biofilms can be bacterial, fungal, or mixed. In the past 15 years, there has been an increasing research effort into antimicrobial surfaces but the great majority of these publications present research on bacteria, with some reports also testing resistance to fungi. Very few studies have focused exclusively on antifungal surfaces. However, with increasing recognition of the importance of fungal infections to human health, particularly related to infections at biomaterials, it would seem that the interest in antifungal surfaces is disproportionately low. In studies of both bacteria and fungi, fungi tend to be the minor focus with hypothesized antibacterial mechanisms of action often generalized to also explain the antifungal effect. Yet bacteria and fungi represent two Distinct biological Domains and possess substantially different cellular physiology and structure. Thus it is questionable whether these generalizations are valid. Here we review the scientific literature focusing on surface coatings prepared with antifungal agents covalently attached to the biomaterial surface. We present a critical analysis of generalizations and their evidence. This review should be of interest to researchers of "antimicrobial" surfaces by addressing specific issues that are key to designing and understanding antifungal biomaterials surfaces and their putative mechanisms of action.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5CC01722J
Abstract: We report a stable plasma polymer coating which releases nitric oxide, inhibiting bacterial growth without cytotoxic side effects.
Publisher: Elsevier BV
Date: 03-2020
Publisher: American Chemical Society (ACS)
Date: 19-04-2012
DOI: 10.1021/AM300128N
Abstract: The deposition of a thin film layer by plasma polymerization enables the surface functionalization of a wide range of substrate materials for biointerfacial interactions. Plasma polymers can surface-bind proteins specifically via covalent linkages or nonspecifically through other irreversible adsorption mechanisms key questions are whether covalent chemisorption has indeed occurred, and whether the protein retains functionality. Here the mode of surface binding of streptavidin and the biotin binding functionality of the bound streptavidin layer are studied on plasma polymer (pp) surfaces deposited using propionaldehyde and ethanol that were plasma polymerized at different powers (P) to investigate possible mechanisms for protein binding to a range of different surface chemistries. As expected, with pp surfaces composed principally of aldehyde groups, protein conjugation appears to be specific (chemisorption) allowing the immobilization of streptavidin (SAV) molecules retaining the ability to bind biotinylated probes. To contrast with this, we present the first study of protein adsorption to ethanol pp surfaces prepared at different P. This provides an investigation into retention of the hydroxyl functionality in the pp at low P and its effect on protein adsorption. Adsorption of human serum albumin (HSA) to ethanol pp was similar to that on propionaldehyde pp except at low P (5 W) where hydroxyl group retention and hydration presumably has a role in reducing protein adsorption. Although we observed SAV adsorption to ethanol pp surfaces at all P, interestingly, the protein lost its ability to bind biotinylated probes. Thus we suggest that irreversible, nonspecific adsorption of protein on ethanol pp surfaces results in apparent protein denaturation despite the hydrophilic nature of the ethanol pp surface. We conclude by making inferences between the pp structure as measured by X-ray photoelectron spectroscopy (XPS) and the related protein adsorption mechanisms.
Publisher: MDPI AG
Date: 31-03-2019
DOI: 10.3390/ANTIBIOTICS8020034
Abstract: Plant metabolites that have shown activity against bacteria and/or environmental fungi represent valuable leads for the identification and development of novel drugs against clinically important human pathogenic fungi. Plants from the genus Eremophila were highly valued in traditional Australian Aboriginal medicinal practices, and E. alternifolia was the most prized among them. As antibacterial activity of extracts from E. alternifolia has been documented, this study addresses the question whether there is also activity against infectious fungal human pathogens. Compounds from leaf-extracts were purified and identified by 1- and 2-D NMR. These were then tested by disk diffusion and broth microdilution assays against ten clinically and environmentally relevant yeast and mould species. The most potent activity was observed with the diterpene compound, 8,19-dihydroxyserrulat-14-ene against Cryptococcus gattii and Cryptococcus neoformans, with minimum inhibition concentrations (MIC) comparable to those of Amphotericin B. This compound also exhibited activity against six Candida species. Combined with previous studies showing an antibacterial effect, this finding could explain a broad antimicrobial effect from Eremophila extracts in their traditional medicinal usage. The discovery of potent antifungal compounds from Eremophila extracts is a promising development in the search for desperately needed antifungal compounds particularly for Cryptococcus infections.
Publisher: American Chemical Society (ACS)
Date: 05-2012
DOI: 10.1021/AM300463Q
Abstract: We describe a method for grafting PEG-based polymer chains of variable surface density using a substrate independent approach, allowing grafting from virtually any material substrate. The approach relies upon initial coupling of a macroinitiator to plasma polymer treated surfaces. The macroinitiator is a novel random terpolymer containing ATRP initiator residues, strongly negatively charged groups, and carboxylic acid moieties that facilitate covalent surface anchoring. Surface-initiated ATRP (SI-ATRP) using polyethylene glycol methyl ether methacrylate (PEGMA) at different concentrations led to grafted surfaces of controlled thickness in either the "brush" or "mushroom" morphology, which was controlled by the abundance of initiator residues in the macroinitiator. Grafted polymer layer structure was investigated via direct interaction force measurements using colloid probe atomic force microscopy (AFM). Equilibrium, hydrated graft layer thicknesses inferred from the highly repulsive AFM force data suggest that the polymer brush graft layer contained polymer chains which were fully stretched. Since the degree of stretching resulted in layer thicknesses approaching the polymer contour length, the polymer brushes studied must be very close to maximum graft density. Grafted layers where the polymer molecules were in the mushroom regime resulted in much thinner layers but the chains had greater chain entropic freedom as indicated by strongly attractive bridging interactions between tethered chains and the silica colloid probe. Use of this experimental methodology would be suitable for preparing grafted polymer layers of a preferred density free from substrate-specific linking chemistries.
Publisher: Elsevier BV
Date: 02-2012
DOI: 10.1016/J.ACTBIO.2011.10.006
Abstract: A general method for producing low-fouling biomaterials on any surface by surface-initiated grafting of polymer brushes is presented. Our procedure uses radiofrequency glow discharge thin film deposition followed by macro-initiator coupling and then surface-initiated atom transfer radical polymerization (SI-ATRP) to prepare neutral polymer brushes on planar substrates. Coatings were produced on substrates with variable interfacial composition and mechanical properties such as hard inorganic/metal substrates (silicon and gold) or flexible (perfluorinated poly(ethylene-co-propylene) film) and rigid (microtitre plates) polymeric materials. First, surfaces were functionalized via deposition of an allylamine plasma polymer thin film followed by covalent coupling of a macro-initiator composed partly of ATRP initiator groups. Successful grafting of a hydrophilic polymer layer was achieved by SI-ATRP of N,N'-dimethylacrylamide in aqueous media at room temperature. We exemplified how this method could be used to create surface coatings with significantly reduced protein adsorption on different material substrates. Protein binding experiments using labelled human serum albumin on grafted materials resulted in quantitative evidence for low-fouling compared to control surfaces.
Publisher: CSIRO Publishing
Date: 2012
DOI: 10.1071/CH11311
Abstract: We have developed a novel method for activating T-cells on material surfaces that enable in idual and population-based analyses of intracellular calcium flux, as a quantitative measure of T-cell receptor engagement. Functionalized material surfaces were created using a plasma-polymerized foundation layer to immobilize stimulatory T-cell ligands, which could induce T-cell receptor-dependent calcium flux in naive T-cells. Real-time confocal microscopic detection and quantification of calcium flux using paired fluorescent ratiometric probes facilitated the tracking and analysis of response profiles of in idual T-cells, as well as population analyses using a combination of in idual T-cell events. This type of combined analysis cannot be achieved using traditional population-based flow cytometric approaches, and thus provides a logical step towards developing the capacity to assess the magnitude and quality of inherently heterogeneous effector T-cell responses to antigenic challenge.
Publisher: American Chemical Society (ACS)
Date: 12-05-2014
DOI: 10.1021/AM501052D
Abstract: A method is described that allows potentially any surface to be functionalized covalently with atom transfer radical polymerization (ATRP) initiators derived from ethyl-2-bromoisobutyrl bromide in a single step. In addition, the initiator surface density was variable and tunable such that the thickness of polymer chain grafted from the surface varied greatly on the surfaces providing ex les, across the surface of a substrate, of increased chain stretching due to the entropic nature of crowded polymer chains leading toward polymer brushes. An initiator gradient of increasing surface density was deposited by plasma copolymerization of an ATRP initiator (ethyl 2-bromoisobutyrate) and a non-ATRP reactive diluent molecule (ethanol). The deposited plasma polymer retained its chemical ability to surface-initiate polymerization reactions as exemplified by N,N'-dimethyl acrylamide and poly(ethylene glycol) methyl ether methacrylate polymerizations, illustrating linear and bottle-brush-like chains, respectively. A large variation in graft thickness was observed from the low to high chain-density side suggesting that chains were forced to stretch away from the surface interface--a consequence of entropic effects resulting from increased surface crowding. The tert-butyl bromide group of ethyl 2-bromoisobutyrate is a commonly used initiator in ATRP, so a method for covalent linkage to any substrate in a single step desirably simplifies the multistep surface activation procedures currently used.
Publisher: American Chemical Society (ACS)
Date: 15-08-2019
Abstract: Microbial pathogens use hydrolases as a virulence strategy to spread disease through tissues and colonize medical device surfaces however, visualizing this process is a technically challenging problem. To better understand the role of secreted fungal hydrolases and their role in
Publisher: Wiley
Date: 15-11-2019
DOI: 10.1002/9781119312994.APR0634
Abstract: To a plant the surrounding environment is filled with microbial organisms looking to take advantage of the bountiful resources held within. In order for a pathogen to access the internal nutrients it must gain entry through the plant cell outer layers that consist of the cuticular wax and the plant cell wall. This barrier is a complex structure composed of erse waxes, lipids, polysaccharides, proteins, lignin, and antimicrobial compounds and plays many crucial roles during plant defence, growth, and development. We now have more evidence than ever about the dynamic nature of the cell wall providing various interaction‐dependent passive and active defence responses, hence justifying a necessity of evolving such a complex structure. Here we summarise the current understanding of this multi‐layered defence system, using the biotrophic interaction between barley and the causal agent of powdery mildew, Blumeria graminis f. sp. hordei ( Bgh ).
Publisher: Elsevier BV
Date: 10-2013
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C7CP08166A
Abstract: The multiple roles hydrogen plays in depositing plasmas is investigated by addition of H 2 O and D 2 O to ethyltrimethylacetate plasmas.
Publisher: American Society for Microbiology
Date: 03-2019
DOI: 10.1128/AAC.02281-18
Abstract: Aspergillus fumigatus infections are associated with high mortality rates and high treatment costs. Limited available antifungals and increasing antifungal resistance highlight an urgent need for new antifungals.
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C7PY01770G
Abstract: A series of polymerized high internal phase emulsion (polyHIPE) materials have been prepared by using a water in oil emulsion stabilized by a macro-RAFT agent, 2-(butylthiocarbonothioylthio)-2-poly(styrene)- b -poly(acrylic acid), acting as a polymeric surfactant.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5TB00961H
Abstract: In this work we have prepared surface coatings formulated with the antifungal drug caspofungin, an approved pharmaceutical lipopeptide compound of the echinocandin drug class.
Publisher: Oxford University Press (OUP)
Date: 29-10-2018
DOI: 10.1093/JAC/DKY437
Abstract: Fungal biofilms caused by Candida spp. are a major contributor to infections originating from infected biomaterial implants. Since echinocandin-class molecules interfere with the integrity of the fungal cell wall, it was hypothesized that surface-immobilized anidulafungin and micafungin could play a role in preventing fungal adhesion and biofilm formation on surfaces. Anidulafungin and micafungin were covalently coupled to biomaterial surfaces and washed. Surface-sensitive instrumental analysis quantitatively and qualitatively confirmed their presence. Analysis after washing experiments provided evidence of their covalent immobilization. The in vitro antifungal properties of surfaces were confirmed using static biofilm assays and fluorescence microscopy kinetic studies. Antifungal surface coatings eliminated 106 cfu/cm2 inoculations of Candida albicans and prevented biofilm formation and hyphal development on coated surfaces. Surfaces were successively exposed to fresh inoculum and were effective for at least five challenges in eliminating adherent yeasts. We have observed antifungal and anti-biofilm activity of surfaces bearing conjugated echinocandins, which operate through surface contact. The analytical and biological evidence suggests an antifungal mechanism for echinocandins that does not rely upon freely diffusing molecules.
Publisher: Wiley
Date: 07-2023
Publisher: American Chemical Society (ACS)
Date: 24-10-2018
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7RA03897F
Abstract: We report a facile, one-step, aqueous surface bioconjugation approach for producing an antifungal surface coating that prevents the formation of fungal biofilms.
Publisher: Elsevier BV
Date: 09-2018
Publisher: Public Library of Science (PLoS)
Date: 02-06-2016
Publisher: American Chemical Society (ACS)
Date: 15-02-2016
Abstract: Controlling the release kinetics from a drug carrier is crucial to maintain a drug's therapeutic window. We report the use of biodegradable porous silicon microparticles (pSi MPs) loaded with the anticancer drug c hothecin, followed by a plasma polymer overcoating using a loudspeaker plasma reactor. Homogenous "Teflon-like" coatings were achieved by tumbling the particles by playing AC/DC's song "Thunderstruck". The overcoating resulted in a markedly slower release of the cytotoxic drug, and this effect correlated positively with the plasma polymer coating times, ranging from 2-fold up to more than 100-fold. Ultimately, upon characterizing and verifying pSi MP production, loading, and coating with analytical methods such as time-of-flight secondary ion mass spectrometry, scanning electron microscopy, thermal gravimetry, water contact angle measurements, and fluorescence microscopy, human neuroblastoma cells were challenged with pSi MPs in an in vitro assay, revealing a significant time delay in cell death onset.
Publisher: American Chemical Society (ACS)
Date: 11-11-2019
DOI: 10.1021/ACS.JPCLETT.9B02855
Abstract: Deposition chemistry from plasma is highly dependent on both the chemistry of the ions arriving at surfaces and the ion energy. Typically, when measuring the energy distribution of ions arriving at surfaces from plasma, it is assumed that the distributions are the same for all ionic species. Using ethyl acetate as a representative organic precursor molecule, we have measured the ion chemistry and ion energy as a function of pressure and power. We show that at low pressure (<2 Pa) this assumption is valid however, at elevated pressures ion-molecule collisions close to the deposition surface affect both the energy and chemistry of these ions. Smaller ions are formed close to the surface and have lower energy than larger ionic species which are formed in the bulk of the plasma. The changes in plasma chemistry therefore are closely linked to the physics of the plasma-surface interface.
Publisher: Public Library of Science (PLoS)
Date: 29-09-2021
DOI: 10.1371/JOURNAL.PONE.0257823
Abstract: Fungal hyphal growth and branching are essential traits that allow fungi to spread and proliferate in many environments. This sustained growth is essential for a myriad of applications in health, agriculture, and industry. However, comparisons between different fungi are difficult in the absence of standardized metrics. Here, we used a microfluidic device featuring four different maze patterns to compare the growth velocity and branching frequency of fourteen filamentous fungi. These measurements result from the collective work of several labs in the form of a competition named the “Fungus Olympics.” The competing fungi included five ascomycete species (ten strains total), two basidiomycete species, and two zygomycete species. We found that growth velocity within a straight channel varied from 1 to 4 μm/min. We also found that the time to complete mazes when fungal hyphae branched or turned at various angles did not correlate with linear growth velocity. We discovered that fungi in our study used one of two distinct strategies to traverse mazes: high-frequency branching in which all possible paths were explored, and low-frequency branching in which only one or two paths were explored. While the high-frequency branching helped fungi escape mazes with sharp turns faster, the low-frequency turning had a significant advantage in mazes with shallower turns. Future work will more systematically examine these trends.
No related organisations have been discovered for Bryan Coad.
Start Date: 03-2015
End Date: 07-2020
Amount: $355,500.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2016
End Date: 09-2019
Amount: $260,000.00
Funder: Australian Research Council
View Funded Activity