Enhanced performance of Candida rugosa lipase immobilized onto alkyl chain modified-magnetic nanocomposites

Lipase-immobilized nanomaterials with high activity and stable reusability would have a great impact in different fields. However, developing such materials has proven to be challenging. Herein, polymer (pAcDED)-coated magnetic nanoparticles (MNPs) displaying long alkyl chains, either octyl (C8) or hexadecyl (C16), have been prepared and used for immobilization of Candida rugosa lipase. The aim of the study was to develop magnetic supports able to bind enzyme via interfacial activation thus to stabilized the lipase open conformation. Among the developed nanosupports, the one endowed with the longest alkyl chains (MNPs-pAcDED-C16) provided the best efficiencies of the immobilized enzyme (70% vs. tributyrin and 130% vs. ethyl butyrate). Such results suggest both enzyme adsorption in open conformation and a change of enzyme specificity during immobilization. The MNPs-pAcDED-C16 system also showed better resistance to temperature inactivation in the 25-70 °C temperature range compared to free lipase and good reusability (4 consecutive cycles). The overall performances together with the convenience in the recovery offered by magnetic separation indicate our surface-modified MNPs as efficient and environmentally compatible materials for lipase immobilization.