Biomass-derived carbon quantum dots as sustainable nanosensors for pesticides and toxic metabolites

Abstract

The large-scale application of organophosphate (OP) pesticides poses serious challenges to food safety, environmental sustainability, and human health, creating an urgent need for rapid and sensitive detection technologies. In recent years, carbon quantum dots (CQDs) derived from natural biomass have emerged as environmentally benign fluorescent nanoprobes, offering tunable photoluminescence, high photostability, and versatile surface functionalities. Some CQD fluorescence sensors of OP pesticides use the quenching mechanisms of inner filter effect (IFE), photoinduced electron transfer (PET), and Förster resonance energy transfer (FRET), with detection limits as low as 0.1–5 ppm towards compounds as varied as methyl parathion, chlorpyrifos, and malathion. In real-sample studies, the sensors obtained satisfactory recovery rates between 88% and 104% in matrices with the use of waters, soil, and fruit extracts with satisfactory reproducibility (RSD < 5%). However, most existing strategies are still limited to controlled lab environments with limited selectivity, stability, and tolerance to the matrix. Additionally, although there has been notable development in the sensing of pesticides, the sensing of toxic OP metabolites such as p-nitrophenol (PNP), a key biomarker of exposure, has still attracted relatively minor interest. This review critically summarizes the recent developments in biomass-derived CQDs for OP pesticide and metabolite detection, highlighting the influence of precursor composition, surface functionalization, and optical quenching pathways on sensing performance. Particular emphasis is placed on structure–function relationships, fluorescence quenching mechanisms, and real-sample validation. By delineating current challenges and opportunities, this review outlines strategies for designing robust, portable, and sustainable CQD-based sensors capable of bridging the gap between proof-of-concept research and practical applications in food safety, environmental monitoring, and human health protection.