Dual fluorescence-colorimetric sensing platform based on the peroxidase-mimetic performance of the Fe₂AlB₂ MAX phase for the quantification of acetamiprid and imidacloprid pesticides

The extensive use of pesticides in modern agriculture has raised concerns about environmental contamination and adverse human health effects. Therefore, developing highly sensitive detection methods to identify pesticide residues is crucial for food safety and ecosystem protection. In this study, the Fe₂AlB₂ MAX phase was synthesized and characterized. After evaluating its peroxidase-mimetic performance using a colorimetric method, a new, sensitive, and simple dual fluorescence-colorimetric sensor was developed for the quantification of two common pesticides, acetamiprid (ACP) and imidacloprid (IMP), using fluorescein (FL). The developed method is based on the inhibitory impact of ACP and IMP on the enzymatic performance of the Fe₂AlB₂ MAX phase, specifically the inhibition of hydroxyl radical (^[rad]OH) generation, which enhances the absorption and emission intensities of FL. The results confirmed that ^[rad]OH generated through the breakdown of H₂O₂ via the catalytic activity of the MAX phase can decrease the intrinsic absorption and emission intensities of FL. However, ACP and IMP inhibit the peroxidase-like activity of the MAX phase, leading to increased absorption and emission intensities of FL. The limit of detection values calculated for spectrophotometric and spectrofluorimetric quantifications were 2.8 μM and 0.051 μM for ACP and 1.72 μM and 0.013 μM for IMP, respectively. Furthermore, the proposed method was successfully utilized to accurately and reliably determine ACP and IMP in spiked real samples with satisfactory accuracy and precision. These developed methods offer several advantages, making them promising candidates for the direct, rapid screening of pesticide residues.