Rational design of a chitosan-coated cobalt ferrite nanozyme coupled with molecularly imprinted polymer for trace analysis of Buspirone in complex matrices: application to spiked human plasma and environmental water samples

Abstract

This study reports the development of a novel high-affinity colorimetric sensor for the anxiolytic drug; Buspirone (BUS) by integrating a polydopamine molecularly imprinted polymer (MIP) onto chitosan-coated cobalt ferrite (CoFeCH) nanozyme. The core of this system utilizes i) bimetallic Co-Fe synergy, where the variable oxidation states of cobalt significantly accelerate electron transfer and reactive oxygen species generation. ii) Surface functionalization with chitosan was employed to stabilize the metallic core and provide abundant amino and hydroxyl anchors for further surface engineering. iii) Facile polydopamine imprinting process, creating specific recognition cavities that selectively bind BUS and modulate the nanozyme’s peroxidase-like activity via target-induced inhibition of H2O2-mediated oxidation of orthophenylenediamine. The fabricated nanozyme was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, and surface area analysis, confirming the successful formation of a porous MIP with highly accessible binding sites. Factors affecting the enzymatic reaction including buffer type and pH, H2O2 concentrations/ratio and reaction time were investigated and optimized. The proposed sensor exhibited a detection limit of 0.08 ng mL-1 for BUS providing a superior sensitivity profile. CoFeCH nanozyme showed fast kinetic profile with Vmax values of 0.04 M.min-1 and 0.07 mM.min-1 for H2O2 and orthophenylenediamine, respectively. This study introduces the first colorimetric sensor based on CoFeCH nanozymes and polydopamine imprinting for BUS detection. The platform was successfully applied for BUS determination in spiked human plasma and Nile water samples, enabling trace-level detection, while offering a robust, rapid, and cost-effective analytical approach for both environmental and therapeutic drug monitoring.