Safe and Intelligent Thermoresponsive β‑Cyclodextrin Pyraclostrobin Microcapsules for Targeted Pesticide Release in Rice Disease Management

This study presents the development of thermoresponsive pyraclostrobin (PYR) microcapsules (PYR@PNIPAm-MCs) designed for controlled temperature-regulated pesticide release. These microcapsules, characterized by a regular spherical shape, smooth surface, and average size of 7.08 μm, achieved a 14.99% drug loading capacity. Wide-angle X-ray diffraction (WAXD) analysis confirmed the efficient encapsulation of PYR. The release kinetics of PYR from the PYR@PNIPAm-MCs demonstrated a sustained, temperature-sensitive release pattern influenced by drug diffusion and matrix erosion. The efficacy of the PYR@PNIPAm-MCs against Magnaporthe oryzae paralleled that of 97% PYR technical concentrate at elevated temperatures. Acute toxicity assays revealed a significantly reduced toxicity of PYR@PNIPAm-MCs to aquatic life (LC₅₀ = 7.71 mg/L), and the formulation showed no adverse effects on rice seedling growth. The results underscore the potential of this formulation to enhance the application of PYR in rice disease management, offering targeted release and improved safety profiles.