This work explores the development of a renewable, carbon-neutral, light-colored UV-shielding film to protect photosensitive pesticides from solar radiation, as these chemicals are easily degraded under UV light, substantially reducing their efficiency and causing soil and water pollution. The abundant benzene rings in lignin and phenolic hydroxyls in tannin boosted the co-self-assembly of lignin and tannin into composite nanospheres by the simultaneous pi-pi stacking and H-bonding interactions between these two biopolymers. These lignin-tannin (LT) composite nanoparticles were used as natural UV-shielding additives to coat a poly-vinyl-alcohol (PVA) film, endowing the PVA-LT film with an excellent UV-shielding ability (>95 % efficiency) due to the strong pi-pi stacking and concentrated phenolic hydroxyls. Typical photosensitive pesticides covered with the PVA-LT film significantly increased their remaining rate by 1.5 times compared to those under the uncoated film. Besides, intensive intermolecular hydrogen bonds were generated between PVA and the abundant phenolic hydroxyl groups exposed on the hydrophilic shell of the LT coating, enhancing the mechanical properties and water vapor retention of the composite film. Our biodegradable composite film derived from natural plant extracts not only protected photosensitive pesticides from UV irradiation but also allowed the transmission of visible light to guarantee the photosynthesis process of crops.

Over the last few decades, there is increasing worldwide concern over human health risks associated with extensive use of pesticides in agriculture. Developing excellent SERS substrate materials to achieve highly sensitive detection of pesticide residues in the food is very necessary owing to their serious threat to human health through food chains. Self -assembled metallic nanoparticles have been demonstrated to be excellent SERS substrate materials. Hence, alkanethiols-protected gold nanoparticles have been successfully prepared for forming larger -scale two-dimensional monolayer films. These films can be disassembled into a fluid state and reassembled back to crystallized structure by controlling surface pressure. Further investigations reveal that their self -assembled structures are mainly dependent on the diameter of gold nanoparticles and ligand length. These results suggest that the size ratio of nanoparticle diameter/ligand length within the range of 4.45 -2.35 facilitates the formation of highly ordered 2D arrays. Furthermore, these arrays present excellent SurfaceEnhanced Raman Scattering performances in the detection of trace thiram, which can cause environmental toxicity to the soil, water, animals and result in severe damage to human health. Therefore, the current study provides an effective way for preparing monodispersed hydrophobic gold nanoparticles and forming highly ordered 2D close -packed SERS substrate materials via self -assembly to detect pesticide residues in food. We believe that, our research provides not only advanced SERS substrate materials for excellent detection performance of thiram in food, but also novel fundamental understandings of self -assembly, manipulation of nanoparticle interactions, and controllable synthesis.

Controlled release of pesticides in response to environmental stimuli using hydrogels as carriers is a feasible approach to improve the effective utilization rates of pesticides. In this regard, modified carboxylated cellulose nanocrystal (CCNC)-based hydrogels with appropriate biocompatibilities and high specific surface areas have broad prospects. Accordingly, in this study, a pH -responsive hydrogel loaded with the pesticide thiamethoxam (TXM) (PEI-CCNC@A-MMT/TXM) was constructed by synergistically introducing CCNC modified with polyethyleneimine (PEI) into cost-effective acidified montmorillonite (A-MMT) via electrostatic self -assembly followed by combination with sodium alginate (SA) by emulsion - gel method via ionic crosslinking. PEI-CCNC@AMMT efficiently improved the mechanical properties of the SA hydrogel and ensured the stability and TXM loading efficiency of this hydrogel; however, the hydrogel stress increased from 9.48 to 41.44 kPa under 20 % compressive strain when the mass ratio of A-MMT to PEI -modified CCNC (PEI-CCNC) was increased from 0 to 0.8. PEI-CCNC@A-MMT/TXM exhibited significant controlled -release characteristics with the change in pH; specifically, with an increase in pH from 5.0 to 9.0, the cumulative release ratio of TXM increased from 53.62 to 94.86 wt % within 48 h of the addition of PEI-CCNC@A-MMT/TXM to the phosphate buffered saline solution. Fitting the six models to the release curves proved that swelling, dissolution, and diffusion acted together during TXM release, and release mechanisms for TXM under different pH conditions were proposed. The release behaviors of PEI-CCNC@A-MMT/TXM in soil indicated that this hydrogel effectively prolonged the release of TXM, and only 91.53 wt % TXM was released within 240 h after the hydrogel entered the soil. The bacterial activity revealed that the hydrogel did not destroy the microbial environment of the soil and demonstrated high biocompatibility. This study provides a promising strategy for regulating the pesticide release behavior, improving pesticide utilization, and reducing environmental pollution of pesticides via introducing low-cost AMMT and green CCNC into the SA hydrogel and applying this hydrogel as a pesticide carrier.

Agrichemical losses are a severe threat to the ecological environment. Additionally, some agrichemical compounds contain abundant salt, which increases the instability of formulations, leading to a lower agrichemical utilization and soil hardening. Fortunately, the biological amphiphilic emulsifier sodium deoxycholate alleviates these problems by forming stable Janus core-shell emulsions through salinity-driven interfacial self-assembly. According to the interfacial behavior, dilational rheology, and molecular dynamics simulations, Janus-emulsion molecules are more closely arranged than traditional-emulsion molecules and generate an oil-water interfacial film that transforms into a gel film. In addition, at the same spray volume, the deposition area of the Janus emulsion increased by 37.70% compared with that of the traditional emulsion. Owing to the topology effect and deformation, the Janus emulsion adheres to rice micropapillae, achieving better flush resistance. Meanwhile, based on response of the Janus emulsion to stimulation by carbon dioxide (CO2), the emulsion lost to the soil can form a rigid shell for inhibiting the release of pesticides and metal ions from harming the soil. The pyraclostrobin release rate decreased by 50.89% at 4 h after the Janus emulsion was exposed to CO2. The Chao1 index of the Janus emulsion was increased by 12.49% as compared to coconut oil delivery in soil microbial community. The Janus emulsion ingested by harmful organisms can be effectively absorbed in the intestine to achieve better control effects. This study provides a simple and effective strategy, which turns waste into treasure, by combining metal ions in agrichemicals with natural amphiphilic molecules to prepare stable emulsions for enhancing agrichemical rainfastness and weakening environmental risk.