APS Homepage

Poster: Biology & Disease Mgmt: Chemical Control


Characterization and Application of Oil-In-Water Nanoemulsion for Controlling Citrus Huanglongbing
M. ZHANG (1), C. Yang (2), C. Powell (1), Y. Duan (3), R. Shatters (3) (1) IRREC-IFAS, University of Florida, U.S.A.; (2) Guangxi University, China; (3) USHRL-USDA-ARS, U.S.A.

Candidatus Liberibacter asiaticus (Las), which can cause destructive citrus huanglongbing (HLB), resides in citrus phloem. Based on various physiochemical characteristics of oils, surfactants, and organic solvents, oil-in-water (O/W) nanoemulsion was optimized to prepare the antimicrobial nano-formulation. The nanoemulsion was produced using a spontaneous emulsification method for the efficient delivery of antimicrobials into citrus phloem by bark application. The nanoemulsion prepared from cremophor® EL (viscous oil), acetone (water miscibility organic solvent), and Span 80/Tween 80 (surfactant) exhibited a small droplet size (17.33±0.52 nm). It also had an improved absorption rate, including 2-day peak concentration (tmax), 71.86±35.38 ng/g maximum concentration (Cmax), and 267.25%±44.1% relative bioavailability (RBA) of ampicillin in HLB-affected citrus compared to the Amp solution alone (tmax = 6 days, Cmax = 56.44±32.59 ng/g and RBA = 100 %). The same nanoemulsion was used to deliver five antimicrobials to control citrus HLB by bark application. We found that droplet size of antimicrobial formulation prepared in nanoemulsion was significantly reduced. And the nanoemulsion also enhanced the efficacy against Las of validoxylamien A, combination of actidone and validoxylamine A, and sulfadimoethoxine sodium against Las. Therefore, this study provides an efficient self-nanoemulsifying delivery system for controlling citrus HLB.