Abstract:
Gold nanoparticles were electrodeposited on the surface of BSPCE using chronoamperometry. A cyclic voltammetric technique was used to graft electropolymerized PNA film on the surface of AuNPs deposited SPCE. The electrodeposited gold nanoparticles were stripped off from electrode surface to create holes on the thin organic film. The modified electrode was characterized using potassium hexacyanoferrate (negative redox probe) and hydroquinone (neutral redox probe). The developed method was then used for the electrochemical determination of caffeine (electropositive analyte). The anodic peak potential for caffeine was shifted to less positive potential with the enhancement of anodic peak current of caffeine at nanohole p-nitroaniline grafted screen printed carbon electrode (nanohole PNA grafted SPCE), which makes it suitable for the determination of caffeine in real sample. Various deposition times of gold nanoparticles were carried out amperommetrically on the surface of BSPCE. The negative potential shift with the increase in the anodic peak current of caffeine was obtained at a 10 s deposition time. Thus, for the cyclic voltammetric study of caffeine, 10 s depositions of gold nanoparticles were used as an optimum deposition time. At an optimized conditions, the oxidation peak current of caffeine was linearly related to the concentration of caffeine in the range of 6 to 16 µM with a correlation coefficient and detection limit (LOD=3ó/Slope) of 0.99943 and 1.92 x10 -7 M, respectively. Sensor response of caffeine was not affected by possible interfering species as the result obtained from the cyclic voltammetric experiment of the mixture of theophyline and caffeine indicates which showed the selectivity of the modified electrode. The modified electrode has also good reproducibility and stability.
