| Summary: | Chitosan/silver nanofluids were prepared using <i>Phoenix dactylifera</i> (DPLE) or <i>Rumex vesicarius</i> (HEL) extracts as the reducing agent, characterized using Fourier-transform infrared spectroscopy (FTIR), ultraviolet–visible (UV-vis), X-ray diffraction (XRD), and transmission electron microscope (TEM). The antimicrobial effect of the nanofluids against Gram positive, <i>Bacillus licheniformis</i>, <i>Staphylococcus haemolyticus</i>, <i>Bacillus cereus</i>, and <i>Micrococcus luteus</i>, and Gram-negative <i>Pseudomonas aeruginosa</i>, <i>Pseudomonas citronellolis</i>, and <i>Escherichia coli</i> bacteria has been studied. The nanoparticles were polydispersed in the chitosan matrix and are highly stable. The zeta potential of the silver nanoparticles in DPLE- and HEL-mediated composites is +46 mV and +56 mV, respectively. The FTIR results reveal that the free carboxylate groups in the plant biomaterial took part in stabilization process. HEL is a stronger reducing agent than DPLE and nanoparticles generated with HEL are smaller (8.0–36 nm) than those produced with DPLE (10–43 nm). DPLE- and HEL-mediated composites effectively inhibit the growth of the studied bacteria but HEL-mediated composite exhibited higher effect. The higher antimicrobial activity of HEL-mediated composite is linked to the smaller nanoparticles. The foregoing results indicate that HEL extract can be used in the green production of potential antimicrobial chitosan/silver nanofluids for biomedical and packaging applications.
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