Entrapping enzyme in a functionalized nanoporous support.

The enzyme organophosphorus hydrolase (OPH) was spontaneously entrapped in carboxylethyl- or aminopropyl-functionalized mesoporous silica with rigid, uniform open-pore geometry (30 nm). This approach yielded larger amounts of protein loading and much higher specific activity of the enzyme when compared to the unfunctionalized mesoporous silica and normal porous silica with the same pore size. When OPH was incubated with the functionalized mesoporous silica, protein molecules were sequestered in or excluded from the porous material, depending on electrostatic interaction with the charged functional groups. OPH entrapped in the organically functionalized nanopores showed an exceptional high immobilization efficiency of more than 200% and enhanced stability far exceeding that of the free enzyme in solution. The combination of high protein loading, high immobilization efficiency and stability is attributed to the large and uniform pore structure, and to the optimum environment introduced by the functional groups.