Acetal Prodrug Self-Assembly Based on Salicylaldehyde for Efficient Management of Plant Disease and Postharvest Preservation

Aldehyde-containing plant-derived ingredients (PDIs) are promising eco-friendly alternatives to synthetic pesticides, but their application is limited by instability and poor bioavailability. Self-assembly of prodrug has attracted extensive attention due to the simple preparation process, excellent physicochemical properties, and targeted release effect. Herein, to address the practical application challenges of PDIs, three kinds of salicylaldehyde acetal prodrugs (SAPs) were synthesized by separately coupling salicylaldehyde (SAL) with ethylene glycol, 1,2-butanediol, and pentaerythritol using newly prepared functional ionic liquid as catalysts and subsequently self-assembled into nanoparticles (SAP NPs) in aqueous solution under additive-free conditions via multiple noncovalent interactions. The polyol components in SAPs imparted the SAP NPs with excellent foliar adhesion, enhanced resistance to volatilization, and a pH-responsive release profile under pathogenic microenvironments or postharvest fruit senescence. Consequently, the SAP NPs significantly enhanced the stability and bioavailability of SAL, leading to superior antifungal, nematocidal, and postharvest preservation efficacy. In addition, the SAP NPs demonstrated favorable biosafety profiles in both tomato plants and Vicia faba root tip cells. This work presents a self-assembly strategy for acetal prodrugs that significantly enhances the stability, targeting capacity, and functional versatility of SAL, offering a sustainable and efficient alternative for crop protection and postharvest management.