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)/β-cyclodextrin (PDDA/β-CD) composite film. The optimized 5-bilayer PDDA/β-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 β-CD components. Electrochemical impedance spectroscopy showed a minimum charge transfer resistance of 119 Ω for the 1-bilayer modified electrode. The sensor showed two distinct linear response intervals (0.01–50 μM and 50–500 μM) and was able to detect concentrations as low as 0.03 μM. 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/β-CD composite sensor offers a simple, cost-effective, and environmentally friendly platform for paracetamol analysis in pharmaceutical and practical applications.