Electrochemical Detection of Melatonin at Tungsten Oxide Nanospheres Decorated Chitosan Electrode

Melatonin is a clinically important hormone as it plays a key role in maintaining immune system, circadian rhythm, blood pressure and cortisol levels. Therefore, its real time detection is crucial for monitoring body function. Melatonin detection by electrochemical sensors exhibits advantages such as high sensitivity, point-of-care analysis, rapid response time, easy to use and cost-effective. Natural polymer based biocomposites including chitosan, gum acacia, xanthan gum, chitin are widely employed due to their ready availability, low cost, biocompatibility and high surface area for biosensing applications. Herein, we investigated tungsten oxide (WO 3 ) nanospheres decorated with functionalized chitosan (FCH) for melatonin detection. The functionalization of chitosan introduced plentiful amine groups and inter-hydrogen bonding that are essential for the formation of WO 3 /FCH biocomposite. Further, the large density of amine groups offered efficient binding affinity with WO 3 and improved the conductivity of the nanocomposite thereby enabling sensitive melatonin detection. Electroanalysis confirmed the excellent electrocatalytic performance of the biocomposite towards melatonin with a limit of detection of 4.9 nM. The proposed nanocomposite exhibited excellent selectivity, reproducibility, stability. Further, its practical reliability was evaluated in real samples thereby demonstrating its usefulness in the detection of clinically relevant biomolecules.