A comparative study on lipase immobilized polypropylene microfiltration membranes modified by sugar-containing polymer and polypeptide

Two protocols were used to modify polypropylene microfiltration membrane (PPMM): (a) a sugar-containing polymer was grafted onto the membrane surface by the plasma-induced polymerization of α-allyl glucoside (AG) and (b) poly(γ-stearyl l-glutamate) (PSLG) was tethered onto the membrane surface through the ring opening polymerization of N-carboxyanhydride (NCA) derived from γ-stearyl l-glutamate. Lipases from Candida rugosa were immobilized on these membranes by adsorption. Results on the basis of the enzyme adsorption capacity, activity and thermal stability were compared with those of the nascent PPMM. It was found that, as for the PAG-modified PPMM, the adsorption capacity and the activity retention of lipases were lower than those of the nascent ones, but the thermal stability was improved to some degree. On the other hand, tethering PSLG on the membrane surface increased the activity retention of lipases immobilized on the membrane from 57 to 72%, and the thermal stability was also improved.