A novel antibacterial and anti-biofilm material: Biosynthetic silver nanoparticles mediated by extract from Oplopanax elatus adventitious roots

The search for plant resources involved in the biosynthesis of silver nanoparticles (AgNPs) is crucial for the diversity of AgNP materials. Oplopanax elatus is a valuable medicinal shrub and its adventitious root (AR) culture is a modern method for producing the raw material. To explore an efficient biosynthetic AgNPs, this study synthesized AgNPs using O. elatus AR extract (OE-AgNPs) and the characterization of OE-AgNPs was performed. Finally, the antibacterial and anti-biofilm effects of OE-AgNPs were investigated. The result showed that OE-AgNPs had an obvious absorption peak of nanosilver with a spherical shape and a silver-like face-centered cubic structure, which the OE-AgNPs were capped by compounds with aliphatic amine, amide, carbonyl, and hydroxyl groups of O. elatus AR extract, indicating a successful synthesis of OE-AgNPs. The 10–40 nm particles were the most abundant in the OE-AgNPs, accounting for 70%. OE-AgNPs had the strongest antibacterial activity against Escherichia coli and Pseudomonas aeruginosa among six bacterial species tested, with a minimum inhibitory concentration (MIC) of 0.75 μg/mL, and the cell contents of E. coli and P. aeruginosa leaked out by OE-AgNP treatment, and bacterial respiration was inhibited. After OE-AgNP treatment, biofilms of E. coli and P. aeruginosa were efficiently scavenged with a scavenging rate of more than 60%; the extracellular polysaccharide concentrations in biofilms were also ruduced. The findings of this study suggested that OE-AgNPs could be used as a potential antibacterial and antibiofilm substance to apply in the product production and indicated the feasibility of expanding the application of O. elatus ARs.