Smart Sensing on Silicon: Molecularly Imprinted Polymer Platforms for Selective and Scalable Electrochemical Devices

Abstract

The integration of molecularly imprinted polymers (MIPs) onto silicon-based microfabricated electrodes represents a frontier in the development of selective, miniaturized, and intelligent electrochemical sensors. This approach merges the molecular recognition precision of synthetic polymers with the reproducibility and scalability of microfabrication technologies, opening new pathways toward compact, high-performance analytical platforms. In this work, nanocrystalline graphite (NCG) is employed as the primary electrode material owing to its exceptional conductivity, chemical stability, and compatibility with silicon processing. Its nanostructured surface promotes strong adhesion and uniform distribution of polymer films, while facilitating rapid electron transfer across the sensing interface. To achieve molecular selectivity, MIP layers based on chitosan and polypyrrole (PPy) are electropolymerized on the NCG microelectrodes. Chitosan provides a biocompatible and chemically versatile scaffold capable of forming hydrogen bonds and coordinating with target analytes, whereas polypyrrole contributes high electrical conductivity and structural integrity to the recognition matrix. The imprinting process is designed for two environmentally critical pollutants: glyphosate, a widely used organophosphorus herbicide with potential carcinogenic effects, and bisphenol A (BPA), a known endocrine disruptor associated with plastic waste contamination. The accurate, on-site detection of these molecules is crucial for addressing global challenges related to environmental safety, food quality, and human health. Beyond conventional MIP systems, this work introduces an advanced molecularly imprinted nanozyme (MINZ) architecture, achieved by integrating sulfur-doped graphene (S–Gr) into the polymer matrix. The incorporation of S–Gr significantly enhances the electron transfer kinetics and catalytic properties of the hybrid layer due to sulfur-induced defect sites that act as active catalytic centers. These heteroatom-doped graphene networks mimic natural enzyme-like behavior, providing peroxidase- and oxidase-like activity that amplifies electrochemical signals while preserving molecular recognition fidelity. The resulting MIP–S–Gr hybrid behaves as an artificial nanozyme layer capable of selective recognition and signal transduction, thus representing the next level of intelligent sensing interfaces. The synergy between the silicon-based microelectrode platform, nanocrystalline graphite, biopolymer–conductive polymer hybrid MIPs, and sulfur-doped graphene nanozyme nanostructures establishes a multifunctional sensing interface that is selective, stable, and scalable. This architecture supports real-time and in situ monitoring of hazardous organic contaminants, with potential for integration into lab-on-chip and portable devices. Overall, this study demonstrates a promising strategy toward next-generation molecularly imprinted nanozyme electrochemical sensors, combining nanostructured materials, green polymer chemistry, and silicon microtechnology for advanced environmental and biomedical applications. Figure 1