Modulating Selectivity of Avocado Seed-Derived Carbon Dots Toward Pesticides: Role of Synthesis Temperature on Paraquat Detection

Abstract

The widespread use of pesticides in agriculture has boosted productivity but raised environmental and health concerns due to their persistence and toxicity. In this study, carbon dots (CDs) were synthesized from avocado seed, a sustainable biomass precursor, via carbonization at 250, 400, and 600 °C. The influence of synthesis temperature on structural, surface, and optical properties was systematically examined along with the sensing performance towards pesticides.  All the proposed nanoprobes were tested against malathion, dimethoate, dichlorvos, diazinon, paraquat, propiconazole, glyphosate, and chlorpyrifos. Results revealed a clear synthesis temperature-dependent selectivity toward paraquat, attributed to variations in surface functionality and electronic structure that modulate CDs interaction with the analytes and charge-transfer processes.  Paraquat was detected with a limit of detection (LOD) of ~2.5μM. These findings highlight the critical role of synthesis conditions in tuning specificity and provide insight into the relationships among structure, optical properties, and selectivity of biomass-derived CDs for pesticide sensing.