Protection of opening lids: very high catalytic activity of lipase immobilized on core-shell nanoparticles.

Various hydrophobic supports have been used for lipase immobilization since the active site of lipase can be opened in a hydrophobic environment. Nevertheless, the increase of lipase activity is still limited. This study demonstrates a hyperactivation-protection strategy of lipase after immobilization on poly(n-butyl acrylate)-polyaldehyde dextran (PBA-PAD) core-shell nanoparticles. The inner hydrophobic PBA domain helps to rearrange lipase conformation to a more active form after immobilization into the PAD shell. More importantly, the outer PAD shell with dense polysaccharide chains prevents the immobilized lipase from contact with outside aqueous medium and revert its conformation back to an inactive form. As a result, under optimal conditions the activity of lipase immobilized in PBA-PAD nanoparticles was enhanced 40 times over the free one, much higher than in any previous report. Furthermore, the immobilized lipase retained more than 80 % of its activity after 10 reaction cycles.