Green synthesis and primary mechanism of AgNPs-Codonopsis pilosula stem solution with efficient antibacterial and catalytic reduction properties of antibiotic.

Converting plant waste to nanosilver has been introduced in agro-waste re-utilization, but this technology confronts limitation due to complex synthesis mechanism. Codonopsis pilosula stem (SCP) yield is increasing after harvest, its re-utilization is promising, but few research has been conducted yet. This study converted SCP to self-assembled nano-silver material to cost-effective reuse. The results showed the UV spectrum obtained the highest absorption at 422-437 nm. The temperature, time, and the amount of extraction solution presented significant impact on the characterization of the synthesized material. The samples obtained relatively more stable Zeta potential in the presence of plant chemicals than AgNPs alone. AgNPs-Codonopsis pilosula performed excellent antibacterial activities when diluted for 80-1280 times with high potential, especially for drug-resistant strains. Moreover, the chemical components in the plant solution exert a synergistic antibacterial effect with AgNPs. The material can also be used as catalyst for antibiotic reduction of tetracycline, penicillin, streptomycin sulfate with reduction rate of 23.01% - 56.53%. The method of unraveling synthesis mechanism by metabolomics and UPLC-MS/MS analysis were employed for the first time. The components dominating reaction were benzene, carboxylic acid and their derivatives, fatty acyl and organic oxygen compounds. The significant reduction of dl-homocysteine and other chemicals were observed in reaction. This study provided new insights for antibacterial material for drug-resistant strains and novel antibiotic-degrading material, explored key parameters for industrial production and new method in unrevealing synthesis mechanism of plant-mediated AgNPs. Additionally, it provided ideas for innovative utilization of agro-waste.