Layer-by-layer self-assembled poly(diallyldimethylammonium chloride)/ cyclodextrin composite materials for the electrochemical detection of paracetamol

This study reports the development of a sensitive electrochemical sensor for paracetamol detection based on a layer-by-layer self-assembled poly(diallyl dimethylammonium chloride)/beta-cyclodextrin (PDDA/beta-CD) composite film. The optimized 5-bilayer PDDA/beta-CD modified glassy carbon electrode exhibited enhanced electron transfer kinetics and analyte preconcentration. Scanning electron microscopy revealed a porous, three-dimensional network structure, while X-ray photoelectron spectroscopy confirmed the successful incorporation of both PDDA and beta-CD components. Electrochemical impedance spectroscopy showed a minimum charge transfer resistance of 119 Omega for the 1-bilayer modified electrode. The sensor showed two distinct linear response intervals (0.01-50 mu M and 50-500 mu M) and was able to detect concentrations as low as 0.03 mu M. The investigation into pH dependence suggested that paracetamol oxidation follows a two-electron, two-proton mechanism, with the best results observed at pH 7.0. The modified electrode showed excellent selectivity, maintaining its response in the presence of common interferents at 10-fold excess concentrations. The sensor showed consistent results (relative standard deviation (RSD) = 3.2 %, n = 5) and remained stable over time, maintaining 92 % of its original performance after a month. Practical applicability was demonstrated through accurate paracetamol determination in pharmaceutical formulations (recoveries 98.6-101.2 %) and spiked urine samples (recoveries 97.8-102.5 %). The proposed PDDA/beta-CD composite sensor offers a simple, cost-effective, and environmentally friendly platform for paracetamol analysis in pharmaceutical and practical applications.