Imobilização de enzimas em nanopartículas magnéticas visando a aplicação na produção de ésteres

Abstract

In the context of the pursuit of sustainable development the use of chemical catalysts is a problem to be analyzed, a relevant proposal is the use of biocatalysts, since these are highly selective and consequently the unwanted reactions are reduced. Candida antarctica type B lipases (CALB) are enzymes that naturally hydrolyze triglycerides, but in medium with low water content they are capable of catalyzing reactions of esterification, interesterification and transesterification. However, the use of enzymes as homogeneous catalysts is limited due to the difficulty of the separation process. This issue can be solved using supports for enzymatic immobilization that maintain their catalytic characteristics. In the present work, iron magnetic nanoparticles (Fe3O4) (NPM) were evaluated as a support for the immobilization of CALB. The biocatalyst was used in the catalysis of the esterification reaction to produce ethyl butyrate. Esters of short chain fatty acids are widely used in food, beverage, cosmetic and pharmaceutical industries with components of flavor and fragrance. These aromas are commonly extracted from nature, but due to environmental issues the availability of this product may be compromised. The nanoparticles were obtained by the co-precipitation technique. The surface of the nanoparticles was modified with aminopropyltriethoxysilane and glutaraldehyde. In the process of Immobilization, the influence of the enzymatic charge (50-200 UpNPB.g-1) and the APTES/Magnetite ratio (1: 1, 1: 3, 1:4 by mass of APTS) and reuse of the biocatalyst were evaluated. The optimum conditions of immobilization were: The enzymatic loading (200 UpNPB.g-1) and ratio of 1: 3 APTES / Magnetite. Immobilization was performed in the presence of 100 mM sodium bicarbonate buffer, pH 10, 25øC. The best conditions for ester production were 25øC, heptane as solvent, molar ratio of 1: 1, 0.4 mol / L of substrates, 150 rpm and 8 h reaction. Maximum conversion of ethyl butyrate (80%) was obtained after 8 hours of reaction at 25 ° C using CALB immobilized on magnetic nanoparticles. The consecutive reaction cycles showed that after 11 cycles, 45% conversion was maintained. The results indicate a great potential for the use of the biocatalyst in the synthesis of high added value esters.