Immobilization of lipase from Candida rugosa on electrospun polysulfone nanofibrous membranes by adsorption

Polysulfone composite nanofibrous membranes were prepared by electrospinning and were used to immobilize lipase from Candida rugosa by physical adsorption. Field emission scanning electron microscopy was used to evaluate the morphology and diameter of the nanofibers. PVP and PEG were used as additives to render the nanofibrous membranes biocompatibility favored by immobilized enzyme. Effects of post-treatment, additive concentration, pH and temperature were investigated on the adsorption capacity and activity of immobilization preparations, as well as thermal stability. It was found that (1) post-treatment had no significant effect on the adsorption capacity; (2) the increment of PVP or PEG concentration was negative for the adsorption capacity but positive for activity of immobilized lipase; (3) the immobilized lipase showed less sensitivity for pH and higher optimum temperature. Thermal stability for the immobilization preparations was enhanced compared with that for free preparations. The kinetic parameters of the free and immobilized lipases, Km and Vmax were also assayed. Results indicated that Km and Vmax for the immobilized lipases were higher and lower than those for free lipase, respectively.