Polylactic Acid-Graphene Oxide-based Materials for Loading and Sustained Release of Poorly Soluble Pesticides.

Abstract

A pesticide carrier system can offer advantages to active components, such as improving shelf life, extending the lasting period, and reducing toxicity, all of which could reduce the adverse effects of pesticides on the environment. Graphene oxide (GO) is a promising medical drug carrier material, and its research in the field of pesticides is still in the exploration stage. Herein, in order to load water-insoluble pesticides, a series of polylactic acid-graphene oxides (PLA-GOs) were produced incorporating small amounts (0.1-1 wt %) of GO using acetone-chloroform and N,N-dimethylformamide-dichloromethane, two dual-solvent systems. The prepared PLA-GO carrier materials were characterized by FT-IR, Raman spectroscopy, and differential scanning calorimetry analysis, and their effects on rice growth within 20 days were also evaluated. When the amount of GO added was 0.5% and the solvent system was acetone-chloroform, the amount of pyraclostrobin (Pyr) loaded on PLA-GO (A-0.5%) was very high (39.89%). The PLA-GO pesticide microsphere showed a significantly sustained release of Pyr (up to 30 d). Furthermore, the indoor bioassay results showed that the PLA-GO pesticide microsphere (EC50 = 1.2682) had the best fungicidal activity against Rhizoctonia solani, followed by Pyr technical (EC50 = 2.3137) and commercial Pyr microcapsule suspension (EC50 = 3.4570). In conclusion, it was found that PLA-GOs prepared using the acetone-chloroform system were more suitable as a pesticide carrier, which provided a preliminary basis for GO to realize the coating of water-insoluble pesticides.