Apta-photonic biosensor based on cholesteric liquid crystal network nanoarchitectonics for the visual detection of thiamethoxam

Abstract In this study, we present a cholesteric liquid crystal network-based (CLCN) apta-photonic biosensor for the selective and real-time detection of thiamethoxam, a widely used neonicotinoid pesticide. The biosensor utilizes aptamers for target recognition, coupled with the optical photonic properties of CLCNs to produce visible color changes in response to pesticide binding. The CLCN aptamer biosensor was optimized for thiamethoxam detection, demonstrating high selectivity, sensitivity, and portability. We investigated the immobilization of thiamethoxam-specific aptamers on the CLCN matrix and quantified the biosensor’s response to varying pesticide concentrations. The sensor showed a significant blue shift in its optical response, with a limit of detection of 2.307 nM and a linear detection range of 5–65 nM. The selectivity of the biosensor was confirmed by testing it against other common agricultural pesticides, with minimal interference from non-target analytes. Furthermore, the biosensor’s performance was evaluated in environmental samples, demonstrating its practical application for real-time monitoring of thiamethoxam contamination in water samples. This portable, battery-free optical sensor may provide a practical platform for environmental and agricultural monitoring, supporting on-site detection with reduced infrastructure requirements.