Eco-friendly and sustainable fluorescent film sensors based on dual design strategy for rapid trace Cu2+detection in agriculture

The presence of heavy metal ion Cu2+ in agriculture poses a direct or indirect threat to human health, resulting in irreversible harm. Fluorescent film sensors, as promising sensing platforms, face challenges such as limited sensitivity and relatively long response times. In this work, we proposed a dual design strategy to fabricate highly sensitive film sensors capable of detecting trace Cu2+ in agriculture. The prepared PPYBA-SA hydrogel film owning the three-dimensional (3D) network structure exposed huge interaction interface for PPYBA and ions, which enables immediate detection of Cu2+. The limit of detection of PPYBA-SA hydrogel film can achieve 1.81 nM for Cu2+ ion benefitting from excellent "molecular line effect" of PPYBA and good porous structure of hydrogel. Successful applications to tap water and vegetable samples affirm the PPYBA-SA hydrogel film's efficacy in tracing Cu2+ in agriculture. In addition, the film substrate demonstrates rapid degradation within 24 h, which aligns with the principle of sustainable development. This study presents a novel idea for creating ecofriendly and sustainable fluorescence sensors.