Nanofunctionalization of Cinnamaldehyde via Supramolecular Self-Assembly for Safe and Efficient Plant Disease Management

Plant-derived cinnamaldehyde is emerging as a promising alternative to synthetic pesticides because of its potent antifungal activity and favorable biocompatibility. However, its practical application in agriculture remains constrained by its high volatility and poor aqueous solubility, which significantly limit its stability and bioavailability. In this study, a supramolecular self-assembly strategy was employed to achieve the nanofunctionalization of cinnamaldehyde (CA), a representative volatile essential oil. By introducing tannic acid (TA), surfactant-free CA-TA nanoemulsions (NEs) were successfully prepared, and they exhibited excellent foliar spreading performance and strong antifungal activity against the target pathogens Rhizoctonia solani and Botrytis cinerea. Copper ions (Cu2+) were then incorporated to induce cross-linking, resulting in the formation of CA-TA-Cu nanoparticles (NPs) with enhanced structural stability and pH-responsive properties that facilitate targeted release in the acidic microenvironments associated with fungal infection. The synergistic antimicrobial interaction between CA and Cu2+ further improved the antifungal performance, with EC50 values of 32.69 and 113.97 mg/L against R. solani and B. cinerea, respectively, which slightly surpassed those of CA-TA NEs. The entire nanoformulation process relied exclusively on natural components and excluded toxic solvents, and the cross-linked structures imparted superior biodegradability, biosafety, and biocompatibility. These features were confirmed by toxicity testing using zebrafish embryos and in vitro cytotoxicity assays using normal human dermal fibroblasts (NHDFs), which showed improved safety compared with direct exposure to CA-TA NEs. Overall, this study presents a sustainable and efficient nanodelivery platform for volatile bioactives, thus offering a viable strategy for reducing dependence on conventional chemical pesticides in agriculture.