, Volume 21, Issue 3, pp 427-438
Date: 08 May 2010

Antibacterial Activity of Light-Activated Silicone Containing Methylene Blue and Gold Nanoparticles of Different Sizes

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Methylene Blue and methylene blue-gold nanoparticle mixtures were encapsulated in a silicone polymer using a swell-encapsulation-shrink technique. The antibacterial properties of the materials, when tested against Escherichia coli and Staphylococcus epidermidis, and exposed to laser light (660 nm), were significantly affected by both the presence and size of Au nanoparticles. Bacterial inactivation data were analysed using the Weibull inactivation model. For both E. coli and S. epidermidis the value of the parameter, indicating the time required to achieve the first log10 reduction in the viable count, decreased when Au nanoparticles of ca 2 nm diameter were present. Larger Au nanoparticles (diameters of 5 and 20 nm) in combination with methylene blue were also embedded in silicone. The values of these materials increased with nanoparticle diameter, indicating a reduction in antibacterial activity. In all cases E. coli had higher values than S. epidermidis.

This paper is dedicated to friend and mentor Professor Malcolm Chisholm FRS on the occasion of his 65th birthday.