A Fe ³⁺ -Phenylalanine Coordinated 3D Network To Deliver Pesticide for Controlling Fungal Diseases and Enhancing Salt Stress Tolerance in Crops

The rapid development of nanotechnology has provided new paradigms for modern agricultural science. Nanocarrier structures and compositions are being designed and optimized to generate cutting edge, high-performance functional nanoagrochemicals for use in agriculture. Herein, we used phenylalanine (Phe) as an organic ligand, hexadecyl trimethylammonium bromide (CTAB) as a template, and the iron ion (Fe 3+ ) as the coordinating metal core to construct an amino acid-based 3D network to deliver fungicide fluazinam (Flu) for the smart treatment of crop fungal diseases and improving resistance to salt stress. Fe-Phe@Flu nanoparticles (NPs) were spherical with a loading rate of 41.8% and exhibited an excellent acid-responsive release behavior. The foliar adhesion of the NPs was significantly enhanced due to the introduction of Phe. The fluorescence tracing experiment indicated that the NPs were absorbed and translocated in the pathogenic mycelium and nontarget crops. The fungicidal activities of the NPs on Rhizoctonia solani and Botrytis cinerea were concentration-dependent, with EC 50 values being 67.86 and 15.38% lower, respectively, compared with those of Flu Technical Control (TC). Fe-Phe nanocarriers promoted crop growth by providing trace elements and essential amino acids. The salt stress damage was obviously alleviated by activating the activities of antioxidant enzymes and upregulating the levels of glutamic acid and proline, two key salt stress-responsive amino acids. The benign biosafety of the Fe-Phe nanocarrier was further evaluated. This minimally formulated and eco-friendly amino acid-based nanocarrier provides an innovative solution for the development of sustainable agriculture.