Self-sterilising surfaces to combat healthcare associated infections

Abstract

The immobilisation of photosensitisers on polymeric supports for use in photodynamic antimicrobial chemotherapy has become increasingly popular. The immobilisation of photosensitisers on polymeric supports has been attempted previously by covalent attachment between the photosensitiser and the support, and by entrapping the photosensitiser in a polymeric matrix. Even though porphyrins have been attached to polymeric supports there have been relatively few biological experiments carried out following immobilisation. There have also been few attempts at measuring the reusability of a surface incorporating a photosensitiser for bacterial inactivation. The work presented herein will focus on two main goals; the first is the formation of a self-sterilising surface which will activate under irradiation with visible light, allowing normal lighting conditions to be used, the second goal that will be targeted is the formation of a porphyrin immobilised on a polymeric surface which exhibits minimal leaching, and shows good anti-bacterial activity.Synthesis of a range of conjugatable porphyrins and viologens bearing complementary peripheral functionalities has been carried out, followed by conjugation to solid supports using both microwave heating and normal heating.Entrapment of polyviologens and porphyrins in two different polymeric matrices, silica and polyacrylamide, has been attempted. The entrapment was carried out using different solvent systems, and although it was found to be successful, both porphyrin and polyviologen were found to leach from the polymeric support upon washing. An alternative strategy was attempted via the formation of a water-soluble porphyrin containing a vinyl functionality for use in free radical polymerisation reactions.The synthesis of a library of water-soluble porphyrins bearing vinyl groups was carried out. The library allowed for comparison of a non-metallated porphyrin, acting as a positive control, a copper porphyrin which acted as a negative control and a palladium porphyrin, which was found to produce the highest degree of inactivation of the Gram-negative bacteria E.coli

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