Water-in-Silicone Oil Emulsion Stabilizing Surfactants Formed From Native Albumin and alpha,omega-Triethoxysilylpropyl-Polydimethylsiloxane

摘要

Contact with hydrophobic silicones frequently leads to protein denaturation.However,it is demonstrated that albumin in water-in-silicone oil emulsions retains its native structure in the presence of a functional,triethoxysilyl-terminated silicone polymer,TES-PDMS.Both HSA and TES-PDMS were essential for the formation of stable water-in-silicone oil emulsions:attempts to generate stable emulsions using independently either the protein or the functionalized silicone as a surfactant failed.Confocal microscopy indicated that the human serum albumin(HSA)preferentially adsorbed at the oil/water interface,even in the presence of another protein(glucose oxidase).A variety of experiments demonstrated that the hydrolysis of the Si-OEt groups on the functional silicone occurred only to a limited extent,consistent with the absence of a covalent linkage between the silicone and protein,or of cross-linked silicones at the interface.The fluorescence spectra of HSA extracted from the emulsions,front-faced fluorescence experiments on the HSA/silicone emulsion itself,and HSA/salicylate binding studies all demonstrated that the stability of the water/oil interface decreased as the protein began to unfold:unfolding of the protein in the emulsion was slower than in aqueous solution.The experimental evidence indicated that the interaction between HSA and TES-PDMS is not associated with either homomolecular(HSA/HSA;TES-PDMS/TES-PDMS)interactions or with covalent linkage between two the polymers.Rather,the data is consistent with the direct binding of unhydrolyzed Si(OEt)3 groups to native HSA.The nature of these interactions is discussed.