<![CDATA[Bacterial leaf blight caused by Xanthomonas oryzae pv. oryzae is a major constraint in rice cultivation because it can substantially reduce crop yields. Continuous use of synthetic bactericides risks inducing pathogen resistance and environmental pollution, so safer control alternatives are needed. This study aimed to develop and characterize chitosan-alginate-based nanocapsules containing betel leaf (Piper betle) polyphenols and to evaluate their antibacterial activity against Xanthomonas oryzae pv. oryzae. The nanocapsules were fabricated via the ionic gelation method using betel leaf polyphenol extract, chitosan, and alginate. Particle characteristics were analyzed using Scanning Electron Microscopy (SEM) and a Particle Size Analyzer (PSA), while antibacterial activity was assessed using the agar well-diffusion method. SEM results revealed particles with generally good morphology, although some agglomeration was observed. PSA analysis of the best formulation (K3S3) yielded an average particle size of 330.1 nm with a Polydispersity Index (PDI) of 0.169, indicating a relatively uniform size distribution. However, none of the nine formulations produced a measurable inhibition zone against the test bacteria. This outcome is presumed to result from the controlled release of polyphenols from the chitosan-alginate matrix, so that the concentration of active compounds reaching the medium during incubation was insufficient to inhibit bacterial growth. Thus, nanocapsules were successfully formed at the nanoscale with acceptable physical characteristics, but antibacterial activity was not observed under the tested well-diffusion conditions.]]>
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