ORIGINAL ABSTRACT

Biomass-derived polysaccharide macromolecules have emerged as sustainable, biocompatible functional materials for green agricultural and food applications, owing to their tunable surface groups, self-assembly properties and environmental friendliness. MOFs hold great sensing potential for their superior structural properties, while pure MOFs have critical flaws (severe agglomeration, low mass transfer, poor specificity/stability) in practice, limiting their broader deployment. To address this challenge, a general strategy for structural regulation of UiO-66-OH using green and sustainable carboxylated cellulose nanofibrils (CNFs, a typical linear polysaccharide biomacromolecule) as the sole biogenic modulator and nano-template was proposed. Driven by the competitive coordination and nano-templating effects of CNFs, the defective nanosized UiO-66-OH features abundant active sites and amplified fluorescence signals, modulating the intramolecular charge transfer (ICT) effect for sensitive pesticide detection. In the presence of the target analyte, a distinct fluorescence enhancement was achieved, with an LOD of 1.40 μg/kg (far below the international glyphosate MRL of 0.1 mg/kg in grains) and robust anti-interference against 17 common interferents. Additionally, leveraging the self-assembly properties of CNFs polysaccharide, a food-grade multifunctional fruit coating was fabricated via spray coating, enabling in-situ visual monitoring of pesticide residues and fruit freshness, pesticide degradation, and long-acting fruit preservation. This work offers a rational material design insight and technical support for high-value utilization of cellulose-based biomacromolecules, as well as the green governance of agricultural pesticide residues and high-efficiency fruit preservation.