Preparation of porous chitosan/GPTMS hybrid membrane and its application in affinity sorption for tyrosinase purification with Agaricus bisporus

In this study NaCl particles (porogen) and γ-glycidoxypropyltrimethoxysilane (GPTMS) (cross-linking agent) were used to make chitosan–silica porous hybrid membranes. An optimal chitosan/GPTMS weight ratio 1:1 was found to prepare a novel CSG1.0 membrane. Both macropores (10.72–202.29 μm) in the membrane matrix and micropores (0.008–0.01 μm) in the skeleton of the macropores were observed on CSG1.0. Five compounds, histidine, glutamic acid, tyrosine, l-DOPA, and p-aminobenzoic acid were individually grafted onto CSG1.0. They are linked as ligands by genipin for affinity adsorption of tyrosinase from a crude Agaricus bisporus solution. This study indicates the p-aminobenzoic acid (ABA) grafted chitosan membrane (CSG-ABA) exhibited the best sorption capacity on tyrosinase. Only one band on SDS-PAGE gel was found from the eluted protein of CSG-ABA that identified the selective adsorption of CSG-ABA on tyrosinase. The behavior of tyrosinase sorption by CSG-ABA followed pseudo-first order kinetics. The sorption process was exothermal, and the sorption capacity decreased as the operation temperature increased. The negative value of the sorption ΔS° showed the tyrosinase sorption by CSG-ABA was enthalpic dominant. This study shows CSG1.0 membrane is suitable to be modified for bioproduct separation.