Bacterial Microenvironment-Responsive Nanopesticides for Sustainable Management of Tomato Bacterial Wilt

Pesticide slow/controlled-release technology can significantly improve the effective utilization rate of pesticides. To improve the efficacy of pesticides against target organisms, this study aimed to develop an intelligent nanopesticide formulation with pH-responsive release behavior. Vaterite-type calcium carbonate nanoparticles (CaCO₃) were synthesized using dopamine hydrochloride and bovine serum albumin as modifiers and employed as carriers for loading the active ingredient berberine (Ber). Coordination between Ca²⁺ and the C-O-C group of berberine enabled successful immobilization of berberine onto the surface and into the pores of the calcium carbonate nanoparticles. The resulting Ber@CaCO₃ exhibited favorable pH-responsive release performance in the acidic microenvironment. In vitro release experiments demonstrated that under acidic conditions (pH 3.0), the acid responsiveness of Ber@CaCO₃ increased the cumulative release rate of berberine by 27% compared with that under neutral conditions (pH 7.0). In addition, this study evaluated the biological activity and safety of Ber@CaCO₃ nanocomposites. The EC₅₀ of Ber@CaCO₃ against Ralstonia solanacearum was 17.840 μg·mL^-1, significantly lower than that of free berberine (43.358 μg·mL^-1), indicating enhanced bactericidal activity. A pot experiment showed that Ber@CaCO₃ application reduced tomato bacterial wilt incidence by 27.9%. Safety assessment confirmed that the CaCO₃ carrier had no significant effects on the tomato germination rate, shoot length, or root length, showing good application safety.