Papers by Russell Crawford
Scientific Reports
There has been a growing interest in understanding the ways in which bacteria interact with nano-... more There has been a growing interest in understanding the ways in which bacteria interact with nano-structured surfaces. As a result, there is a need for innovative approaches to enable researchers to visualize the biological processes taking place, despite the fact that it is not possible to directly observe these processes. We present a novel approach for the three-dimensional visualization of bacterial interactions with nano-structured surfaces using the software package Autodesk Maya. Our approach comprises a semi-automated stage, where actual surface topographic parameters, obtained using an atomic force microscope, are imported into Maya via a custom Python script, followed by a 'creative stage', where the bacterial cells and their interactions with the surfaces are visualized using available experimental data. The 'Dynamics' and 'nDynamics' capabilities of the Maya software allowed the construction and visualization of plausible interaction scenarios. Thi...
The design of biomaterial surfaces relies heavily on the ability to accurately measure and visual... more 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 di...
Scientific Reports, 2015
The effect of electromagnetic field (EMF) exposures at the microwave (MW) frequency of 18 GHz, on... more 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.
Journal of colloid and interface science, Jan 15, 2015
A suite of seven different divalent metal ions (Ca(II), Cd(II), Cu(II), Mg(II), Ni(II), Pb(II), Z... more A suite of seven different divalent metal ions (Ca(II), Cd(II), Cu(II), Mg(II), Ni(II), Pb(II), Zn(II)) was adsorbed from solution onto two Fe2O3 samples, quartz SiO2 and three different amphoteric 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 amphoteric latex surface can be increased by decreasing the carboxyl content of the latex surface. For ...
Applied and environmental microbiology, 1999
Degradation of polyvinyl alcohol (PVA) was investigated by using a combination of chemical treatm... more Degradation of polyvinyl alcohol (PVA) was investigated by using a combination of chemical treatment with Fenton's reagent and biological degradation with the white rot fungus Pycnoporus cinnabarinus. Inclusion of the chemical pretreatment resulted in greater degradation of PVA than the degradation observed when biological degradation alone was used.
Nanotechnology, science and applications, 2008
This study reports the adhesion behavior of two bacterial species, Vibrio fischeri and Escherichi... more This study reports the adhesion behavior of two bacterial species, Vibrio fischeri and Escherichia coli, to the photoresistant poly(tert-butyl methacrylate) (P(tBMA)) polymer surface. The data has demonstrated that ultraviolet irradiation of P(tBMA) was able to provide control over bacterial adhesion tendencies. Following photolithography, several of the surface characteristics of P(tBMA) were found to be altered. Atomic force microscopy analysis indicated that photolithographically modified P(tBMA) (henceforth termed 'modified polymer') appeared as a 'nanosmooth' surface with an average surface roughness of 1.6 nm. Although confocal laser scanning microscopy and scanning electron microscopy analysis clearly demonstrated that V. fischeri and E. coli presented largely different patterns of attachment in order to adhere to the same surfaces, both species exhibited a greater adhesion propensity towards the 'nanosmooth' surface. The adhesion of both species to th...
... Full Text PDF (520kb). To cite this article: Guy, David W; Crawford, Russell J and Mainwaring... more ... Full Text PDF (520kb). To cite this article: Guy, David W; Crawford, Russell J and Mainwaring, David E. Surface Chemical Aspects of Wetting and Adhesion on ... (1) Centre for Applied Colloid and BioColloid Science, Department of Applied Chemistry, Swinburne, University of ...
Abstract: Four decades have passed since the inaugural Australian Colloid and Surface Science Stu... more Abstract: Four decades have passed since the inaugural Australian Colloid and Surface Science Student Conference. Russell Crawford and Erica Wanless report on the 40-year history and its celebration. ... To cite this article: Crawford, Russell and Wanless, Erica. Colloid Science: ...
The surface chemistry and nanotopography of poly(ethylene terephthalate) (PET) was successfully m... more The surface chemistry and nanotopography of poly(ethylene terephthalate) (PET) was successfully modified by marine bacteria, indicating the initial stages of biodegradation. PET surfaces became rougher relative to the control surfaces in the presence of bacterial communities regardless of whether they were primarily phototrophic or heterotrophic. Only surfaces exposed to primarily heterotrophic bacteria, however, changed significantly in surface chemistry; these samples showed a decrease in oxygen groups across the surface. The results seem to indicate two different mechanisms of PET degradation depending on whether the bacterial community is primarily phototrophic or heterotrophic.
Insects and plants are two types of organisms that are widely separated on the evolutionary tree;... more Insects and plants are two types of organisms that are widely separated on the evolutionary tree; for example, plants are mostly phototrophic organisms whilst insects are heterotrophic organisms. In order to cope with environmental stresses, their surfaces have developed cuticular layers that consist of highly sophisticated structures. These structures serve a number of purposes, and impart useful properties to these surfaces. These two groups of organisms are the only ones identified thus far that possess truly superhydrophobic and self-cleaning properties. These properties result from their microand nano-scale structures, comprised of three-dimensional wax formations. This review analyzes the surface topologies and surface chemistry of insects and plants in order to identify the features common to both organisms, with particular reference to their superhydrophobic and self-cleaning properties. This information will be valuable when determining the potential application of these surfaces in the design and manufacture of superhydrophobic and self-cleaning devices, including those that can be used in the manufacture of biomedical implants.
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Papers by Russell Crawford