A New Droplet-based Polymeric Banana Electrochemical Biosensor for One Microliter Paracetamol Analysis

Modern researches and also the laboratories increasingly need the methods to measure the small volumes as microliter of analytical samples to identify various analytes with the high accuracy. An electrochemical biosensor based on a modified carbon paste electrode with hydrogel as an absorbent polymeric matrix and banana as a source of polyphenol oxidase was constructed and it was used for determination of paracetamol. The ability of the hydrogel to absorb and retain the liquids, allows us to insert only 1 μL of standard paracetamol solution into the surface of the electrode, in fact we measure the concentration of paracetamol which is at the surface of the electrode, not in solution. The electrochemical oxidation of paracetamol was studied by cyclic voltammetry and square wave voltammetry. The effective parameters on the voltammetric response of the constructed biosensor were optimized. The results obtained by cyclic voltammetry revealed that the banana-hydrogel carbon paste electrode shows a higher current response compared to a banana carbon paste electrode and hydrogel carbon paste electrode. The proposed electrode shows excellent capability to measure only one μL of sample solution, which is very important and considerable property for limited samples in volume. The modified electrode also exhibits an excellent sensitivity (1.6 picomole), a good linear range (10-250 picomole), good reproducibility and stability in both basic and acidic environments even in the presence of the enzyme and a long life time (20 days) for measurement of paracetamol in solutions.