Synthesis and characterization of cross-linked lipase-metal hybrid nanoflowers on graphene oxide with increasing the enzymatic stability and reusability

In the current study, a purified lipase from Enterobacter sp. MG10 has been immobilized in three approaches, including lipase nano-flower (LNF), LNF/graphene oxide (GLNF), and cross-linked GLNF (CGLNF). The encapsulation yield (EY) and activity recovery (AR) were obtained in the range of 40.5 % to 81.0 % and 71.5 % to 132.2 % for lipase MG10, respectively. The best activity recovery was found (132.2 % for 0.02 mg ml−1 enzyme) in the presence of 200 mM of Cu2+ for 72 h incubation at 4 °C. The CGLNF showed broader pH and temperature activities compared to free lipase. Moreover, the CGLNF displayed a 60 % improvement in lipase activity after 28 days of incubation, compared to free lipase. Remarkably, the Km value of CGLNF was 0.980 mM toward the p-NPP substrate, whereas the Km value of free lipase was 17.11 mM at the same condition. Furthermore, the catalytic efficiency of CGLNF was 430.45 S−1 mM−1, compared with 21.32 S−1 mM−1 for the free lipase. The CGLNF showed 93 % efficiency in converting prosopis stephanina oil to biodiesel, whereas it found 63 % for the free lipase. Overall, these results showed the high potential of CGLNF nanobiocatalyst in synthetic biotechnology, especially in biodiesel production.