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Solid phase synthesis of graft copolymers of poly(thiophene)s and peptides containing 3-thienylalanine
Abstract
Graft copolymers of conjugated poly(3-hexylthiophene) and polypeptides containing an artificial amino acid, 3-thienylalanine (3TA), were synthesized and purified using solid phase synthesis techniques. The structures of the graft copolymers were characterized by NMR, and binding of biotinylated graft copolymers to avidin and streptavidin was studied using fluorescence spectroscopy. The hydroxmethylbenzoic acid (HMBA) solid phase resin linker was stable in the presence of an oxidative polymerization catalyst, ferric chloride, for up to five hours as shown by infrared spectroscopy and elemental analysis. A two-level factorial design was used to identify three factors which had statistically significant effects on the solution fluorescence emission maxima of the copolymers: catalyst to monomer ratio, monomer addition rate, and addition of bithiophene. Additionally, two two-factor interactions had significant effects: the interactions of monomer ratio and monomer concentration, and of monomer ratio and addition of Proton-Sponge. A peptide containing 3TA and biocytin, separated by a triglycine spacer, was synthesized on HMBA resin and characterized by mass spectroscopy fragmentation and by two-dimensional correlational NMR spectroscopy. The peptide, and an analog substituting biocytin with an acetylated lysine, were produced in 84 to 89% purity The integrity of the peptide backbone and the successful copolymerization were confirmed by 2D NMR after polymerization. Number average molecular weights of 7300 g/mol for the acetylated lysine copolymer, and 10 850 g/mol for the biocytin copolymer could be estimated from the NMR spectra. Strong fluorescence emission maxima at long wavelengths were observed for the copolymers, indicating high conjugation lengths. This system is not limited to peptides and 3-hexylthiophene, and should be generally applicable to synthesis of copolymers of conjugated polymers and biomolecules that can be immbolilized on a solid support.
Subject Area
Polymers
Recommended Citation
Flanagan, David W, "Solid phase synthesis of graft copolymers of poly(thiophene)s and peptides containing 3-thienylalanine" (2004). Doctoral Dissertations Available from Proquest. AAI3152696.
https://scholarworks.umass.edu/dissertations/AAI3152696