Polyvinylidene fluoride/silane-treated hydroxyapatite mixed matrix membrane for enzyme capturing.

The silane coupling agent, N-(β-aminoethyl)-γ-aminopropyltrimethoxy silane (KH792), was employed to modify the surfaces of nano-hydroxyapatite (HAP) particles. The mixed matrix membranes (MMMs) were prepared by embedding pure HAP and HAP modified with KH792 (KH792-HAP) inside polyvinylidene fluoride (PVDF) matrix respectively. The MMMs were further characterized concerning permeability and adsorption capacity. Langmuir adsorption isotherm provides better fit for HAP and KH792-HAP than Freundlich isotherm. KH792-HAP has better distribution in the polymeric matrix compared to HAP in the polymeric matrix. The MMMs showed purification of enzyme via static adsorption and dynamic adsorption, and showed the potential of using MMMs for enzyme capturing in enzyme purification techniques. The lysozyme (LZ) was used as a model enzyme. The properties and structures of MMMs prepared by immersion phase separation process were characterized by pure water flux, LZ adsorption and scanning electron microscopy (SEM).