Polyhydroxyalkanoate-Based Microparticles for Enhanced Photostability and Controlled Release of Pyraclostrobin

Photodegradation under ultraviolet irradiation significantly limits the efficacy of agrochemicals, leading to reduced field performance and increased environmental burden. Biodegradable polymer-based delivery systems have emerged as a promising strategy to address these limitations. Polyhydroxyalkanoate (PHA)-based microparticles (MPs) encapsulating pyraclostrobin (PYR), a model fungicide, were prepared using an emulsion–solvent evaporation method. The formulations were characterized by physicochemical properties, encapsulation efficiency, and release kinetics. Photostability under UV irradiation and antifungal activity against Aspergillus oryzae were systematically evaluated. As results, the MPs exhibited uniform size distribution and high encapsulation efficiency. Physicochemical analyses confirmed the physical incorporation of PYR within the PHA matrix without chemical alteration. The PHA matrix suppressed UV-induced photodegradation, enhancing photostability. In addition, the system demonstrated sustained release without an initial burst, with release rates dependent on polymer composition. This controlled release behavior resulted in prolonged antifungal activity. Based on these results, PHA-based microencapsulation provides an effective and sustainable strategy to enhance the stability and efficacy of photolabile agrochemicals, offering a versatile platform for advanced pesticide delivery.