Characterization and bioactivities of silver nanoparticles green synthesized from Vietnamese Ganoderma lucidum

In this study, the utilization of Vietnamese Ganoderma lucidum (G. lucidum) extract was scrutinized under different operational conditions including reaction time, AgNO3:extract mass ratio, and reaction temperature to establish a rapid, cost-effective, and eco-friendly method with a high yield rate and nanoparticle stabilization. The characterization showed that the as-synthesized silver nanoparticles (AgNPs) were well-crystalline with an average size of 11.38 +/- 5.51 nm. Meanwhile, the Fourier-transform infrared spectrometry of AgNPs and extract samples showed the absorption bands including -OH stretching, symmetric aliphatic bending, and C-OH stretching vibrations belonging to the presence of polyphenols, triterpenoids, and polysaccharides, respectively. These bands reveal an astounding decline in the polyphenol, triterpenoid, and flavonoid content of the crude G. lucidum extracts, which is consistent with the results obtained from colorimetric methods. In liquid chromatography-mass spectrometry of AgNPs and extract samples, various peaks were detected and they shared significant differences in intensity after the reaction. As a result, the phytochemicals from G. lucidum extracts were confirmed to play the role of reducing silver ions to AgNPs and act as a capping agent to stabilize the colloid mixture. In the biological tests, the colloidal AgNPs demonstrated an extraordinary antimicrobial activity against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella enterica, and Candida albicans, with IC50 values of 17.97, 17.06, 1.32, 54.69, and 27.78 mu g/mL, respectively. The antioxidant capacity of AgNPs was evaluated using 2,2-diphenyl-1-picrylhydrazyl free radical reagent (IC50 = 447.120 +/- 0.084 mu g/mL). In addition, the colloidal AgNPs possessed better anticancer activity against the human epidermic carcinoma cancer cell line (KB) with IC50 values of 190.06 +/- 3.62 mu g/mL when compared to the crude extract. The results of the bioactivity evaluations exhibited the potential utilization of G. lucidum extract as a natural source for the colloidal AgNPs biosynthesis and their application in various areas, particularly as an antimicrobial agent in food, pharmaceutical, and cosmetic product preservation to combat bacterial infection.

Automated summary

This study successfully synthesized silver nanoparticles using Vietnamese Ganoderma lucidum extract, showing good crystallinity and nanoparticle stability. The synthesized silver nanoparticles exhibited excellent antimicrobial and antioxidant activities against various bacteria and fungi, and showed potential in anticancer applications as well.