RESUMO
A new type of magnetic metal chelating carrier (PCMM-IDA-Cu2+) was prepared for the immobilization of papain, using chitosan as raw material, nano Fe3O4 as magnetic material, SiO2 as porogen, iminodiacetic acid (IDA) as a chelating ligand, and binding with transition metal ion (Cu2+). The resulting products were well characterized by optical microscopy, scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The BBD (Box-Behnken Design) of RSM (Response Surface Methodology) was applied to analyze the optimum enzyme immobilization conditions. The results showed that the enzyme immobilization capacity was 94.18mg/g of PCMM-IDA-Cu2+, with 7.976U/mg of relative immobilized enzyme activity under the optimum conditions (pH6.73, 1.56mg enzyme/15.0mg carrier, 30.9°C), and the recovery of enzyme activity was reached 87.21%. Compared with the free papain, the immobilized papain displayed enhanced enzyme activity, superior enzymatic properties, good operational stability and reusability. It is worth mentioning that the novel carriers exhibited selectively biological adsorption capacity, and this technique is an alternative method for the immobilization of enzyme, making the process more efficient and economic.