Facile fabrication of a recyclable nanobiocatalyst: immobilization of <i>Burkholderia cepacia</i> lipase on carbon nanofibers for the kinetic resolution of a racemic atenolol intermediate

Abstract

Immobilization of surfactant treated <i>Burkholderia cepacia</i> lipase on the surface of carbon nanofibers was performed <i>via</i> two different methods: adsorption and covalent attachment. Simple adsorption of lipase on carbon nanofibers turned out to be a poor strategy, exhibiting an immobilization efficiency of 36%, while covalent coupling using 1-ethyl-3-[3-dimethylaminopropyl] carbodiimide (EDC)/<i>N</i>-hydroxysuccinimide (NHS) showed better immobilization efficiency (56%). The nanobioconjugate fabricated using the latter method showed an eleven-fold increase in enzyme activity towards the hydrolysis of <i>p</i>-nitrophenyl palmitate and enhanced dispersion in organic solvents. At 80 °C, the half-life of lipase in the nanobioconjugate was almost 20 fold higher than that of free lipase, demonstrating its thermal stability. The as-prepared nanobioconjugate was reused for nine consecutive reaction cycles achieving 100% yield in the hydrolysis of <i>p</i>-nitrophenol palmitate but losing almost 50% of the initial activity after seven operational cycles. Finally, this heterogeneous nanobioconjugate was more active and enantioselective [<i>C</i> = 47.8, ee_p = 97.0 and <i>E</i> = 194] than free lipase [<i>C</i> = 35.4, ee_p = 97.1 and <i>E</i> = 88] towards the kinetic resolution of a racemic intermediate of atenolol yielding the <i>S</i> enantiomer, which signifies its importance as a nanobiocatalyst.