One-pot synthesis of a hierarchical PMO monolith with superior performance in enzyme immobilization

A novel hierarchical periodic mesoporous organosilica (PMO) monolith is synthesized by using N,S-bis[3-(triethoxysilyl)propyl]-carbamothioic acid for the first time, in order to fabricate a highly efficient enzyme immobilizer. The hierarchical monolith is spontaneously formed with mild shearing force without further additives, in which the primary particles can be selectively prepared to be inter-connected with each other end to end to form a net-like framework throughout the whole monolith, and the inorganic/organic composition is finely controlled by adjusting the initial composition of the silica precursors. As the result, an ordered net framework with micrometer sized macropores and large mesopores is simultaneously obtained together with a high organic content, favoring high enzyme immobilization, in which they demonstrate an enhanced adsorption capacity, superior immobilization stability and good reusability. Especially, the PMO monolith can adsorb 126 mg g^-1 of horseradish peroxidase (HRP), higher than double that of the power-like analogue (38 mg g^-1); and the bioactivity is three times higher than that of the free enzyme, indicating the strong advantages of morphology assistance in enzyme immobilization.