Fluorescent NH-MIL-88(Fe)-stabilized PtNPs Nanozyme for Dual-Channel "OFF-ON" simultaneous and visual detection of glyphosate and Pb in Agri-environments and foodstuffs.

Trace levels of pesticides and heavy metals in the environment and foodstuffs represent a substantial threat to human health. This study presented a bifunctional NH-MIL-88(Fe)@Pt nanozyme possessing superior peroxidase-mimicking activity and fluorescence properties, further establishing a dual-channel "OFF-ON" sensing platform for the simultaneous visual detection of glyphosate (GLY) and Pb. In the "OFF-ON" mechanism, cysteamine (CA)-mediated catalytic suppression of TMB oxidation was reversed through specific Pb chelation, enabling quantitative Pb detection with a limit of detection (LOD) of 0.0049 μg/mL (0.024 μM). The abundant -NH groups on NH-MIL-88(Fe)@Pt induced fluorescence quenching via Cu-triggered Lewis acid-base coordination. The preferential binding of Cu to GLY restored fluorescence, facilitating quantitative detection of GLY (LOD: 0.0082 μg/mL (0.048 μM)). Based on these principles, a hydrogel-based NH-MIL-88(Fe)@Pt nanozyme platform incorporating smartphone analysis was developed to achieve semi-quantitative visual detection of GLY and Pb, demonstrating significant potential for efficient contaminant screening in agri-environments and foodstuffs.