Tailoring Core–Shell Nanocapsules of Abscisic Acid/Tannic Acid–Urea via Mechanochemical Method for Enhanced UV Shielding and Deep Delivery Capabilities

Enhancing the photostability of pesticides is crucial for improving application efficiency and reducing usage frequency. Herein, an abscisic acid (ABA)/tannic acid (TA)-urea (ABA@TA-U) core-shell nanocapsules delivery system was developed using a mechanochemical method for improve ultraviolet (UV) shielding. Benefiting from the solvent-free synthesis strategy, the obtained ABA@TA-U-6 nanocapsules exhibit a broad size distribution (average particle size: 515.8 nm) and high active ingredient loading capacity (77.7%). The TA-U shell provides exceptional UV shielding properties, significantly mitigating ABA photodegradation. Foliar spray and hydroponic experiments demonstrated effective leaves and roots uptake and translocation of ABA@TA-U-6 nanocapsules in cotton seedlings. Proteomic analysis confirmed that ABA@TA-U-6 nanocapsules activated the MAPK pathway and metabolic processes to trigger systemic stress defense. Therefore, the ABA@TA-U-6 nanocapsules system not only effectively protects ABA from UV degradation but also serves as a potent delivery platform for intracellular transport, showcasing significant potential for sustainable agricultural applications.