Effective immobilization of lipase onto a porous gelatin‐co‐Poly(vinyl alcohol) copolymer and evaluation of its hydrolytic properties

Abstract

ABSTRACTCrosslinked copolymers of gelatin and poly(vinyl alcohol) (PVA) with excellent water absorption and water retention abilities were successfully synthesized using 60Co γ radiation. Ammonium persulfate (APS), as a water‐soluble initiator and sodium bicarbonate (NaHCO3) as a foaming agent were used. The best synthesis conditions were evaluated with regard to the maximum percentage of swelling as a function of the APS concentration, NaHCO3 concentration, amount of water, and reaction time. The maximum swelling percentage (1694.59%) of the copolymer gelatin‐co‐PVA, was obtained at the optimum parameters [APS] = 2.92 × 10−1 mol/L, [NaHCO3] = 7.94 × 10−2 mol/L, and 1.5 mL of water with 31.104 kGy of the γ radiation dose. The copolymer was characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) methods. The SEM analysis showed a highly nanoporous and cellular structure of the copolymer. The copolymer was used as a support for lipase immobilization. The optimization of the reaction conditions, including the pH and temperature for immobilization, on the basis of the hydrolysis of p‐nitrophenyl palmitate, was carried out. An excellent efficiency for protein loading (70%) at pH 8.5 by the copolymer was observed. The results observed during the evaluation of the hydrolytic properties showed excellent activity of the bound lipase. The porous gelatin‐co‐PVA bound lipase was found to be stable at 75°C and pH 8.5; it displayed 2.326 ± 0.005 U/g of lipase activity. The stability and activity of the copolymer‐bound lipase were also studied as a function of the time at 75°C, and the biocatalyst was found to be stable and active up to 1 h, beyond which the activity decreased. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39622.