Platinum nanoparticle-carbon nanotubes dispersed in gum Arabic-corn flour composite-enzymes for an electrochemical sucrose sensing in commercial juice

摘要

The aim of the present study was to fabricate a rapid analytical platform for the analysis of saccharide in foods using new bio-composite of nanomaterials in the natural polysaccharides, gum Arabic (GA) and corn flour (CF). The hydrogel was reinforced by metal nanoparticles (PtNPs) anchored with carboxyl-functionalized carbon nanotubes (MWCNTs). The GA-CF composite was investigated for the possibility of co-immobilization of Invertase (Inv) and glucose oxidase (GOx). Physical immobilization of Inv-GOx in the form of thin film resulted in high enzyme retention efficiency (Inv-96.5% and GOx-92%) with excellent storage stability, up to 6 months at room temperature, for both enzymes. The resulting bioactive films were studied for various physicochemical parameters including reproducibility, pH, nanomaterial loading capacity, operational stability, and shelf life. The morphological characterization of the nanocomposite was examined by transmission electron microscopy, and it revealed that the diameter of PtNPs changed from similar to 3.0 to 21 nm due to outer surface coating after immobilization. Uniform dispersion of carbon nanowire network embedded in bi-enzymes/GA-CF composite film was also observed under scanning electron microscopy. Entrapment of MWCNTs and PtNPs in GA-CF carrier resulted in an improved catalytic efficiencies and loading capacity of both enzymes due to larger surface area for entrapment. Screen-printed carbon electrodes (SPCEs) were modified with this novel enzyme-nanocomposite matrix and an electrochemical biosensor (Inv-GOx-MWCNTs-AgNPs/SPCE) was thus developed. The biosensor exhibited excellent sensitivity, good reproducibility, long-term stability, fast amperometric response to sucrose with wide linear range of 1 x 10(-4) to 1 x 10(-9) mol L-1 with a correlation coefficient of 0.99, and better limit of detection (1 x 10(-9) mol L-1) as compared to previous sensors. The sucrose analytical capabilities of the sensor were tested on commercial fruit, vegetable, and mix juice samples, and the validity of the measurement was confirmed by standard DNSA method.