Trifluorosilane induced structural transitions in beta-lactoglobulin in sol and gel.

Fluoroalcohols such as 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) are strong inducers of protein secondary structure. Here, hydrolyzed (3,3,3-trifluoropropyl)trimethoxysilane (3F) is demonstrated to exhibit greater protein conformation inducing activity than HFIP, which is preserved when 3F is copolymerized in tetraethylorthosilicate (TEOS) sol-gels through protein molecular imprinting. Hydrolyzed 3F formed a pre-polymerization complex with the template protein, β-lactoglobulin, inducing distinct α-helical structures as evidenced by circular dichroism. Fluorescence resonance energy transfer between tryptophan and the lipophilic probe 1-anilinonaphthalene-8-sulfonic acid showed a sharp molten globule (MG) transition at 0.2M 3F, whereas HFIP induced a broad MG transition centered at 0.6M HFIP. The 3F-induced BLG conformation transitions were retained upon gelation, validating use of the fluorosilane as a conformation directing functional monomer readily incorporated into sol-gels.