Plasma polymerized coatings that release nitric oxide are compatible with human cells and have a bacteriostatic property. Image (C) Royal Society of Chemistry.
Nitric oxide (NO) plays an incredibly important role in biology which is just beginning to be understood. From pulmonary dilation to wound healing, nitric-oxide based medical therapies are a huge and growing sector of human health.
A further aspect is NO’s ability to interfere with bacterial biofilm formation on surfaces. This opens up the way for new surface coatings that can release NO to stop infections from taking hold on medical devices. A particularly challenging problem, however, is how to easily make surface coatings that store this reactive gas molecule. Furthermore, how can one make such a device containing a volatile, reactive molecule that has a long shelf-life?
Our new publication in Chemical Communications by Thomas Michl and Hans Griesser from the Mawson Institute, University of South Australia shows a method by which coatings that release NO can be deposited on virtually any substrate material. Instead of volatile NO being trapped in the material, the surface coating contains a stable precursor of NO (an polymer containing a nitrosooxy group) that releases NO when exposed to solutions. Materials that were stored on the shelf for up to 2 months retained a bacteriostatic ability showing promise for their anti-biofilm ability. Importantly, when exposed to human stem cells, good compatibility was demonstrated showing that the material coatings were selectively bacteriostatic while being well tolerated by human cells.
The ability to deposit onto a range of different materials used in the medical industry as well as very good shelf life shows great promise for fabricating advanced medical devices with bacteriostatic properties.
Link to article:
Nitric oxide releasing plasma polymer coating with bacteriostatic properties and no cytotoxic side effects
What is the role of surface chemistry and materials science in combating fungal disease?
In my article in Microbiology Australia, I give my perspective on how scientists are transforming surface interfaces into active surfaces through nano-scale surface modifications: On the surface of it: the role of materials science in developing antifungal therapies and diagnostics.
Uniform plasma treatment of micron-sized particles can be challenging because the particles need to be suspended in the plasma discharge. What does this have to do with a common stereo speaker playing music or a rotating apparatus commonly used for purifying organic chemical compounds?
Shake, rattle & roll.
Putting the particles on top of a speaker playing music shakes and rattles the particles in the plasma discharge and allows them to be evenly coated.
Or, tumbling the particles in a rotating flask containing the plasma discharge rolls them around and gives them an even coating.
These are the two ideas behind our new publication from Wark and Mawson Institute researchers in Plasma Processes and Polymers:
Common laboratory or household equipment can be readily adapted to plasma discharge apparatus creating a low-cost, yet effective way to solve the challenge of depositing plasma coatings on small particles.
The article has just been published online. You can read more about it here.
Hospital acquired infections are a public health crisis and a leading cause of death world-wide. In the USA over 200 people die each day from hospital acquired infections with over 80% of these related to contaminated surfaces of implanted medical devices. While there is a good level of understanding and research into bacterial infections, fungal infections are the hidden killers – often missed in diagnosis. Treatment with antifungal drugs is therefore delayed and often comes too late, with devastating consequences. Rapidly multiplying on surfaces in a protected slimy coating known as a biofilm, mature fungal infections can spread into the blood and are often more effective when compared to bacteria in host mortality — giving a less than 50/50 chance of patient survival.
The surface of urinary catheters is frequently a site for bacterial and fungal biofilm growth and often leads to infection.
The understanding of how to fight fungal infections from surfaces will be given a major boost by a 4-year grant from the Australian Research Council’s Discovery Grant Program. Recognizing the need for cross disciplinary research at the nexus of physical chemistry, materials science, and biology, the team led by University of South Australia Researchers (the Mycology / Surface Interfaces Group) will bring together world-leading polymer chemists and mycologists across three countries (Australia, Switzerland and the UK) to drive breakthrough research into effective antifungal surface coatings.
Candida albicans, common and mostly benign to healthy individuals, becomes deadly inside the body when it forms biofilms and invades tissues.
Professor Hans Griesser and Senior Research Fellow Dr. Bryan Coad of UniSA’s Mawson Institute will lead the grant. “This grant will bring Australian discoveries to the forefront in what is a new research area,” says Dr. Coad. “Strengthened by the expertise from our international partners, we see potential to deliver outcomes likely to resonate with our scientific peers the world over.”
The four-year research program will develop advanced material surface coatings at UniSA and unravel the design principles needed to transform them into 3-D polymeric platforms in collaboration with partner investigator Prof. Harm-Anton Klok at EPFL Switzerland, an expert in bioactive polymer coatings. Direct visualization of fungal cells on surfaces using live cell imaging by partner investigator Prof. Nick Read at the University of Manchester (Manchester Fungal Infection Group) will reveal the fate of cells and provide direct evidence for the mechanisms of action. “The team will tie the physical and chemical properties of their surface coatings to their specific biological consequences. For fungi, this has never been done before so there is fantastic opportunity to make fundamental discoveries,” says Dr. Coad.
A graphic I designed for my LinkedIn Profile…
Engagement opportunities for students, researchers, industry
(Work is copyright Bryan Coad, 2014)
I presented this poster at the Australasian Society for Infectious Diseases (ASID) conference earlier this year.
I’m making it available for download for personal/educational use.
Clicking here will link to a PDF download (2 MB) of the full sized poster. The poster is copyrighted and not for reproduction. If you intend to use this work for personal/educational use, please contact me and I will provide a non-watermarked PDF copy.
We have just published another study on polymer brush gradients in Langmuir.
Published in: Bryan R. Coad; Tugba Bilgic; Harm-Anton Klok; Langmuir Article ASAP DOI: 10.1021/la501380m Copyright © 2014 American Chemical Society
This work describes a 3 step method for grafting polymer brushes from any substrate. Subsequent work (which happened to be accepted and published first) shows a 2 step method (see post here).
These two works show good understanding of different systems. First, two different plasma polymer gradients were fabricated based on octadiene/allylamine and ethanol/ethylisobromobutyrate, and polymer grafting was shown for hydroxyethyl methacrylate (HEMA), dimethyl acrylamide (DMA), and poly(ethyleneglycol) methacrylate (PEGMA). Last, we have show in this work gradient brushes grown from silicon wafers, and previously, from plastic coverslips.
I was especially pleased with this work as it gave me an opportunity to work with Prof. Harm-Anton Klok from EPFL in Switzerland. Prof. Klok’s work was an inspiration for me during my PhD and I am very glad to have the chance to work with him in a nice collaboration.
Many thanks goes to him and his student, Tugba Bilgic, for helping me with this work.
Just published communication in RSC Advances.
A new study published from the Mawson Institute and the Wark at UniSA and QUT reveals how a straightforward plasma deposition of an inexpensive compound leads to effective antibacterial surfaces.
Chlorinated surfaces rapidly kill Staphylococcus epidermidis on contact. The action occurs rapidly and there is little difference if the prepared surface is dry, wet or washed.
Read more about this research here.
30 years on, Ghostbusters is still a fantastic movie.
My inspiration for the logo was Candida albicans stained by Calcofluor white: a fluorescent stain for chitin.