RESUMO
Owing to their high surface area, stability, and functional groups on the surface, iron oxide hydroxide nanoparticles have attracted attention as enzymatic support. In this work, a chemometric approach was performed, aiming at the optimization of the horseradish peroxidase (HRP) immobilization process on Δ-FeOOH nanoparticles (NPs). The enzyme/NPs ratio (X1), pH (X2), temperature (X3), and time (X4) were the independent variables analyzed, and immobilized enzyme activity was the response variable (Y). The effects of the factors were studied using a factorial design at two levels (-1 and 1). The biocatalyst obtained was evaluated for the ferulic acid (FA) removal, a pollutant model. The materials were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The SEM images indicated changes in material morphology. The independent variables X1 (-0.57), X2 (0.71), and X4 (0.42) presented the significance effects estimate. The variable combinations resulted in two significance effects estimates, X1*X2 (-0.57) and X2*X4 (0.39). The immobilized HRP by optimized conditions (X1 = 1/63 (enzyme/NPs ratio, X2 = pH 8, X4 = 60 °C, and 30 min) showed high efficiency for FA oxidation (82%).
Assuntos
Enzimas Imobilizadas/metabolismo , Compostos Férricos/química , Peroxidase do Rábano Silvestre/metabolismo , Biocatálise , Ácidos Cumáricos/química , Ácidos Cumáricos/metabolismo , Peroxidase do Rábano Silvestre/ultraestrutura , Nanopartículas/química , Oxirredução , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios XRESUMO
A significant enhancement in the catalytic performance due to enzymes immobilization is a great way to enhance the economics of biocatalytic processes. The soybean peroxidase (SP) immobilization under ferroxyte and the ferulic acid removal by the enzyme free and immobilized were investigated. The immobilization via silica-coated ferroxyte nanoparticles was effective, and immobilization yield of 39%. The scanning electron microscopy (SEM) images showed significant changes in the materials morphology. Substantial differences were observed in the particles' Fourier Transform Infrared (FTIR) spectra. The magnetic catalyst revealed a better performance than the free enzyme in the ferulic acid conversion, presenting a good V max/K m ratio when compared with the free enzyme. The reuse evaluated by ten cycles exhibited excellent recycling, remaining constant between the sixth and seventh cycles. The use of magnetic nanocatalyst becomes possible to eliminate the high operational costs, and complicated steps of the conventional enzymatic processes. Thus, a viable industrial route for the use of the enzyme as catalyst is possible.