Akhlaghi_2022_Mol.Catal_519_112118

Lipase immobilization was performed via physical adsorption on a novel metal-chelating nanostructure consisted of (S)-N-(5-Amino-1-carboxypentyl) iminodiacetic acid (NTA), as a tetra-dentate chelating agent, grafted onto MnFe2O4 nanoparticles coated with carboxymethyl cellulose (CMC) for Co2+-chelated affinity lipase adsorption. The influential immobilization parameters for enzyme adsorption were investigated. The maximum amount of immobilized lipase (8.5 mg/g adsorbent) was obtained at modified conditions with initial enzyme concentration of 2 mg/mL and adsorbent dosage of 1 mg/mL after 90 min incubation at 50 mM buffer citrate at pH 5. The Fourier transform infrared spectroscopy (FTIR), energy dispersive spectroscopy (EDS), and elemental mapping provided evidence of successful immobilization of lipase. The results of kinetic study revealed that the adsorption of lipase followed pseudo second order kinetic model. Investigation on the enzymatic properties demonstrated that the immobilized lipase possesses remarkable thermal stability at 60 degreesC for 120 min, as the catalytic activity of immobilized lipase was 75% higher than that of free lipase at the same temperature. Beside, the immobilized lipase still retained 70% of its initial activity after 7 successive recycles, suggesting the new designed Co2+-chelated magnetic nanostructure as a great matrix for the non-covalent enzyme immobilization.