Proteins at silicone interfaces

Although enzymes are normally exploited in aqueous, biological environments, certain enzymes can be made to operate in organic media. We report the utilization of enzymes in active form in a yet more hydrophobic silicone medium, in both liquid and elastomeric forms, by using suitable non-ionic surfactants. The enzymatic activity, depending on the protein, can be shown to be even higher than in organic media, if the concentration of water is appropriately controlled. α-Chymotrypsin, an enzyme readily denatured by simple silicone oils when bulk water is present, can be rendered highly active in both silicone oils and silicone elastomers when stabilized with poly(ethylene oxide) based surfactants: human serum albumin was similarly unaffected by the liquid silicone when surfactants were present. Lipase was shown to have a higher activity in silicone elastomers than in hydrocarbon solvents, but only if PEO constituents were not added. The factors necessary to stabilize protein structure and retain enzymatic activity, such as water content and the presence of PEO, in a silicone-rich environment are described. © 2007 American Chemical Society.