Carrier-Free Small Molecular Self-Assembly Based on Berberine and Curcumin Incorporated in Submicron Particles for Improving Antimicrobial Activity
Yuyang Tian, Gang Tang, Yunhao Gao, Xi Chen, Zhiyuan Zhou, Yan Li, Xuan Li, Huachen Wang, Xueyang Yu, Laixin Luo, Yongsong Cao
Abstract
Nanocarrier-based pesticide formulations have been severely restricted in agriculture practices due to their high-cost preparation process, poor loading capacity, and toxicity issues. To overcome these issues, carrier-free small molecular self-assembled submicron particles (SMPs) with an improved photoactivated antimicrobial activity based on two natural microbicides berberine hydrochloride (BBR) and curcumin (CM) are constructed by noncovalent interactions through a simple and fast preparation process (solvent exchange method) without using any adjuvant. The results show that the optimized molar ratio of BBR to CM is 2:1 at pH 5 and 25 °C in an aqueous solution for the formation of B–C SMPs. The obtained B–C SMPs exhibit excellent physicochemical properties, such as uniform morphology (407 nm), low polydispersity index (0.283), and strong ζ-potential (+24.4 mV). The antibacterial activities of B–C SMPs against Pseudomonas syringae pv. lachrymans, Clavibater michiganensis subsp. Michiganensis, and Sclerotinia sclerotiorum are 4, 2, and 1.5 times that of B + C MIX, respectively, suggesting a synergistic antimicrobial activity based on BBR and CM incorporation in the submicron particles. The genotoxicity evaluation results show that the self-assembled B–C SMPs are harmless to plant cells. Therefore, due to rational utilization of natural resources (natural microbicides, sunlight, and oxygen), carrier-free small molecular self-assembled B–C SMPs with synergistic photoactivated antimicrobial activity developed by a simple and fast preparation process would have great potential for sustainable plant disease management.