Biogenic gold nanoparticles of Salvia species in dyes degradation and detection of lead(II)

The present study describes synthesis of Salvia species (S. plebeia and S. moorcroftiana) mediated gold nanoparticles using deionized water and ethanol as extracting solvents. The study further quantify total phenolic and flavonoids content, assessment of antioxidative and microbial inhibitory potential, and catalytic and sensing abilities of the synthesized gold nanoparticles in dyes degradation and heavy metals sensing. Quantifying the phenolic content, ethyl acetate extract of S. moorcroftiana exhibited the high content (327.2 mg gallic acid equivalent per gram) followed by ethanol and methanol extracts. However, S. plebeia was comparatively low in total phenolic content. In total flavonoid content quantification, methanol and ethanol extracts of S. moorcroftiana exhibited statistically same content (406.9 mg quercetin equivalent per gram and 400.8 mg quercetin equivalent per gram, respectively) followed by ethyl acetate extract. In synthesis of Salvia aqueous mediated gold nanoparticles, ratio/concentration (extract/salt solution) of 1:20 resulted in the most intense and sharp peak at 520–530 nm, whereas ethanolic extract produced reasonable and prominent nanoparticles under sunlight with 1:5 to 1:10 concentration. Assessing the antioxidant and antibacterial activities, Salvia extracts and the nanoparticles were potent antiradical and antibacterial agents. Furthermore, the subject nanoparticles have shown reasonable degradation of Congo red, methylene blue, and methyl orange, and sensing property to detect lead(II) in river water. Hence, Salvia species and the nanoparticles could be used in curing diseases involving free radicals, infections, and remediation of environmental contamination with dyes and lead(II).