Determination of effective assay parameters on the activity of magnetite cross-linked invertase aggregates by personal glucose meter

Abstract

The invertase enzyme has been immobilized onto various support materials to enhance operational stability, shelf life, and reusability compared to free ones. Among the immobilization methods, carrier-free immobilization, such as cross-linked enzyme aggregates (CLEAs), attracts attention. However, recovery of the CLEAs from the reaction environment by centrifugation or filtration is a great challenge. The use of magnetic nanoparticles (Fe3O4) can overcome these separation limitations of the aggregates. For this aim, in this study, the surface of magnetite nanoparticles was functionalized with a significant number of free amino groups through silanization reaction. After precipitation of these aggregates and then cross-linking to the functionalized structure, the resulting magnetite cross-linked invertase aggregates (MCLIAs) were obtained, having different enzyme and glutaraldehyde concentrations. Magnetic nanoparticles were characterized by SEM, VSM, and FTIR analysis. The assay parameters, both constructional and experimental ones on the activity of MCLIAs, were practically determined by a personal glucose meter (PGM). The results indicate that magnetite nanoparticles with superparamagnetic behaviour were successfully functionalized with amino groups. The activity results demonstrated that experimental parameters were more effective than constructional parameters. MCLIAs also exhibited maximum activity at pH 5. Furthermore, 30-min incubation time and 35 °C were the best activity assay conditions.