Peroxidase-like activity of gum kondagogu reduced/stabilized palladium nanoparticles and its analytical application for colorimetric detection of glucose in biological samples

The peroxidase like activity of gum kondagogu (Cochlospermum gossypium) reduced/stabilized palladium nanoparticles (GK-Pd NPs) was investigated using 3,3′,5,5′-tetramethylbenzidine (TMB) as a chromogen in the presence of H2O2. GK-Pd NPs could catalyze oxidization of TMB by H2O2 to produce a blue coloured oxidation product which is quantified using UV–vis spectrophotometer (UV–vis) at λmax of 652 nm. Effect of various reaction conditions, such as temperature, pH and nanoparticle concentration on the catalytic activity of GK-Pd NPs was studied. The peroxidase like catalysis of GK-Pd NPs was found to follow Michaelis–Menten kinetics. The calculated kinetic parameters of the GK-Pd NPs catalysis showed strong affinity towards both, the substrate (H2O2) and the chromogen (TMB). It is known that the oxidation of glucose by glucose oxidase (GOx) enzyme leads to the formation of gluconic acid and H2O2 is generated as a by product. The H2O2 released in this reaction was consequently quantified using GK-Pd NPs as peroxides mimics and TMB as chromogen. Thus, a combination of above two reactions was exploited to establish glucose concentrations. Under the optimum conditions, the linear range of this method was from 10 μM to 1000 μM with the detection limit down to 6.0 μM. Moreover, the developed method was applied to detect glucose in serum samples and the results were in good agreement with standard GOD-POD method.