In-situ coordination assembly of polyphenol with cage-like Prussian blue as an ecofriendly nanocarrier for site-specific pesticide delivery and sustained pest control

In sustainable agricultural production, an efficient and environmental-friendly nanoplatform for precise pesticide delivery is considerably desirable to enhance efficacy and minimize ecological side effects. In this study, a pH-responsive nanohybrid named EB@HMPB@TA was designed using hollow mesoporous Prussian blue (HMPB) coordinated with tannin (TA) for targeted delivery of emamectin benzoate (EB). Results demonstrated that the cage-like HMPB nanoparticles possessed a remarkable loading capacity for EB, reaching up to 63.7%. Through a coordination assembly process, an in-situ Fe3+-chelated TA coating was formed on the surface of EB@HMPB to obtain EB@HMPB@TA. Notably, EB@HMPB@TA appreciably improved the foliar affinity of EB. Moreover, under UV-light irradiation, the degradation rate of EB loaded in the HMPB@TA nanocarriers decreased by 47% compared to EB alone, thus reducing the loss of EB. Additionally, the release ratio of EB@HMPB@TA at pH = 8.5 was 9.47-fold higher than that at neutral pH over 48 h. This pH-dependent release feature held great potential for targeting lepidopteran pests, which own a unique alkaline gut environment. Importantly, compared to commercial EB suspension concentrate, EB@HMPB@TA exhibited potent insecticidal activity against three target pests. Safety evaluations conducted on both HK-2 cells in vitro and maize crops demonstrated the relative safety of EB@HMPB@TA. Consequently, EB@HMPB@TA offered a new approach for accurate pesticide delivery, facilitating efficient and eco-friendly pest control practices and holding tremendous potential for sustainable agricultural production, which aligns with the principles of cleaner production in agriculture.