(512c) Surface Functionalization of Magnetic Nanoparticles for Covalent Immobilization of Candida Antarctica Lipase B

The Lipase B from Candida Antarctica (Calb, EC 3.1.1.3), an enzyme capable of performing a wide variety of reactions, such as hydrolysis, transesterification, and aldol reactions, can be immobilized onto functionalized magnetic nanoparticles, preserving its enzymatic activity. The immobilized enzyme can be easily recovered from the reactional media with a magnet, allowing its reuse. Beyond these properties, it has environmental compatibilities, being considered a green chemistry, allowing high recovering and long catalytic useful life. Iron magnetic nanoparticles (Fe₃O₄) were produced by co-precipitation method. The size (31.1nm) and density (5.24 g/cm³) of the nanoparticles were measured using the technique of X-ray diffraction (XRD) with subsequent refinement of the phases obtained by the Rietveld method. Modifications were carried out on the nanoparticles surface with g-aminopropyltriethoxysilane (APTS). Modification with APTS in the presence of nitrogen was also analyzed. After this modification, the structures were activated with 25% glutaraldehyde solution. The experimental conditions of Calb immobilization in functionalized magnetic nanoparticles, stirring speed (20-45 rpm), enzyme load (50-650 UpNPB/g_support), incubation time (0,5-5 hours) and reuse of the biocatalyst (five cycles) were optimized. The immobilization was performed in presence of 100mM bicarbonate buffer, pH 10, at 25 ºC. After immobilization, Calb exhibited improved thermal and operational stabilities. The best result (Immobilization yield: 53% and immobilized enzyme activity: 29.1 UpNPB/g_support) was obtained at 45 rpm, using 200 UpNPB/g_support and 1h of incubation. Furthermore, immobilized Calb maintained approximately 53% of initial activity after five cycles of hydrolysis.