Sol−Gel Materials as Efficient Enzyme Protectors: Preserving the Activity of Phosphatases under Extreme pH Conditions

By entrapment in (surfactant modified) silica sol-gel matrixes, alkaline phosphatase (AlP) -- naturally with optimum activity at pH 9.5 -- was kept functioning at extreme acidic environments as low as pH 0.9, and acid phosphatase (AcP) -- naturally with optimum activity at pH 4.5 -- was kept functioning at extreme alkaline environments, up to pH 13.0. Propositions are offered as to the origin of the ability of the matrixes to provide such highly efficient protection and as to the origin of the synergetic enhancing effect when both the silica and the surfactants are used as a combined entrapping environment. It was found that the protectability of the enzymes against harsh pH values is dependent on the nature of the surfactant.