Hydrogel Embedding\nEnables Enhanced Leaf Deposition\nand Bioavailability of Fe-Based Engineered Nanoparticles

Nanofertilizers comprising engineered nanoparticles (ENPs)\nhave\ngreat potential in sustainable agriculture due to their strong capabilities\nof improving crop yields. As an effective fertilization strategy,\nfoliar spraying could lead to broken and splashed ENP droplets, resulting\nin inaccurate leaf targeting and potential environmental contamination.\nHerein, we propose embedding Fe-based ENPs into a supramolecular hydrogel\nto effectively enhance the deposition amount on leaves and thus the\nbioavailability. The proper rheological properties of the hydrogel\ndroplets and their robust interaction with soybean leaf simultaneously\nreduce the droplet rebound and fragmentation, especially under elevated\nimpact speeds, resulting in up to 168.9% more droplet deposition compared\nto the ENP suspension. Computational fluid dynamics simulation analysis\nsuggests that the contact angle is a key sensitive factor influencing\nthe dynamic deposition behavior of the hydrogel droplet. A 15% reduction\nin the contact angle results in a 14% reduction of the highest bouncing\nheight. The incorporation of ENPs enhances the viscous dissipation\nrate by 7.4% in comparison with pure hydrogel droplets. The hydrogel\nembedding also causes a 1.5-fold increase in ENP uptake compared to\nthat of the ENP suspension. The hydrogel embedding delivers a reduction\nof 80% in the ENP application amount, compared to ENP suspensions,\nwhile achieving a 28% increase in the fresh weight of soybean seedlings.\nThis work provides an effective method to enhance the deposition of\nENPs during foliar application.