Fabrication and functionalization of magnesium nanoparticle for lipase immobilization in n-propyl gallate synthesis

Abstract An extracellular lipase partially purified from Bacillus thermoamylovorans BHK67 was effectively immobilized onto modified magnetic MgFe 2 O 4 nanoparticles (NPs). NPs were prepared by the sol-gel auto-combustion method and characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Ultra-Violet–Visible Spectroscopy (UV–vis) and atomic force microscopy (AFM). Protein loading reached a saturated amount of about 0.20 mg lipase per milligram of MgFe 2 O 4 NPs with 78.9% binding efficiency. The NPs-bound lipase also showed stability following exposure to n -propanol and iso -propanol or FeCl 2 and MgCl 2 metal ions at (1 mM) at 55 °C. NPs-bound lipase also retained 50% of its original hydrolytic activity even after 8 th cycle, as well as after 12 h of incubation at 55 °C. NPs-bound lipase in an esterification reaction of n -propanol and gallic acid (25 mM) performed for 12 h at 55 °C produced n -propyl gallate with a conversion rate of 82%. Synthesized n -propyl gallate possessed strong antioxidant activity, which was confirmed by DPPH assay, and in addition has anticancerous activity which was tested on a human L132 cell line.