Photobactericidal polymers; the incorporation of crystal violet and nanogold into medical grade silicone

Abstract

Crystal violet and 2 nm gold nanoparticles were incorporated into medical grade silicone polymers by use of a novel two-step dipping strategy using water and water-acetone mixtures. Optical microscopic examination showed that the optimised polymer incorporated dye close to the polymer surface, with minimal dye encapsulation throughout the polymer bulk. The modified polymer was stable under aqueous conditions with negligible leaching of crystal violet from the polymer into surrounding aqueous solution at 37 uC. Exposure of the modified silicone to low power 635 nm laser light induced the lethal photosensitisation of both Staphylococcus epidermidis and Escherichia coli. Despite the laser used not matching the absorption maximum of the crystal violet-containing silicone samples, the lethal photosensitisation was the highest reported, in terms of bacterial kill per energy dose. Furthermore, surprisingly, some statistically significant dark kill was also noted.

Cationic benzylidene cyclopentanone photosensitizers for selective photodynamic inactivation of bacteria over mammalian cells

“…The significant photodynamic inactivation efficiencies of these PSs against the Gram-(+) Staphylococcus aureus (S. aureus, ATCC 6538), Gram-(-) Escherichia coli (E. coli, ATCC 25922), and drug resistant strain E. coli (CA-31) are studied. Methylene blue (MB), 25 …”

White Light-Activated Antimicrobial Paint using Crystal Violet

“…We have shown that the dyes can be readily impregnated into polymers using a swell-encapsulation-shrink process, and the polymers showed potent photobactericidal activity in white light 44,55 . In addition, incorporation of gold (Au) nanoparticles into a dye impregnated polymer significantly enhanced the photobactericidal effect 54,56 .…”

CHAPTER 14. Antimicrobial Interfaces

“…The development of light-activated antimicrobial surfaces such as crystal violet and nanogold incorporated silicone which kill S. epidermidis and E. coli by the action of light have been developed recently. 105 Likewise it was reported that light activation led to a decrease in S. aureus attachment among certain Ni-Ti alloy surface materials covered with titanium dioxide. 106 This was suggested to be due to the photon accumulation in the surface and likely increase in defects which could have resulted in free oxygen.…”