Title

Photochemistry and application of protein-bound dyes and dye-amine conjugates in the presence of visible light

Date of Completion

January 2001

Keywords

Chemistry, Organic|Chemistry, Polymer|Chemistry, Radiation

Degree

Ph.D.

Abstract

Radical ions are well recognized as important species because of their significant chemical and biological applications. The controlled generation of radical ions can have a number of significant biological and chemical applications ranging from utility in organic synthesis, sequence targeted DNA cleavage, selective cell destruction or new methods of initiating polymerization. This research focuses on two avenues for the generation of reactive intermediates using visible light and dye sensitizers. One of the avenues involves the use of imtramolecularly linked xanthene dye-reductant pairs and the other involves the use of dye protein aggregates. ^ The first step was the synthesis of the donor-acceptor conjugates involving the xanthene dye rose Bengal and two different amines. The intramolecular photoinduced electron transfer reactions of the derivatives of rose Bengal, covalently attached to reductants (diisopropyl amine or di-n-butyl amine) was then studied, followed by the investigation of their utility as initiators for polymerization of acrylic monomers in the presence of visible light. Relative rates of polymerization under aerobic and anaerobic conditions gave an insight into the mechanistic aspects of the reaction. The results indicate that the above photoinitiators synthesized were efficient in inducing polymerization of acrylic monomers. ^ In a separate study, the photophysical effects of binding of different families of dyes (triphenylmethane, azo, pyrene and quinoline) with proteins was studied. These dye-protein aggregates were further utilized as initiators for photopolymerization of acrylic monomers in the presence of visible light. The variation of polymerization rate with the concentration of the protein, the dye structure and its concentration, and whether the reaction was blanketed with nitrogen was examined. The polymerization reactions took place at reasonable rates (within 60 minutes). These results suggest the possible role of some of these dyes as polymerization catalysts, though they had previously seemed inactive. ^ As an extension of the work with acrylic monomers, the photoinduced formation of hydrogels comprised of BSA-PEG-diacrylate systems in the presence of different classes of dyes using visible light was studied. These photocurable substances might conceivably be useful as wound healing materials such as tissue adhesive sealants, surface coating for implanted devices or as a matrix for drug delivery. ^