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Exploring bimetallic Au–Ag core shell nanoparticles reduced using leaf extract of Ocimum tenuiflorum as a potential antibacterial and nanocatalytic agent

Sneha Nayak, Chandrayan Vaman Rao, and Srinivas Mutalik

Department of Biotechnology Engineering, NMAM Institute of Technology- Affiliated to NITTE (Deemed to be University), Mangalore, India



Received: 24 February 2022  Accepted: 25 May 2022


Biosynthesis of bimetallic Au–Ag core shell nanoparticle under ambient condition using Ocimum tenuiflorum (Krishna Tulsi) leaf extract is being reported for the first time. For the biosynthesized bimetallic core shell nanoparticles (OTAuAgNPs) visual and spectrophotometric analysis was performed. Development of a deep purple color suggested the creation of OTAuAgNPs. It was then validated by UV–Vis spectrophotometry within 4 h of incubation showing a surface plasmon resonance peak at 560 nm. FESEM-EDAX, FT-IR, particle analyzer and XRD were the analytical techniques employed to characterize the biosynthesized OTAuAgNPs. Using a known antibiotic as a control, OTAuAgNPs (10 mg/ml) had a substantial bacteriostatic effect against Gram + ve (Bacillus subtilis) and Gram −ve (E.coli, Pseudomonas aeruginosa) bacteria. The OTAuAgNPs (6.5 mg) showed good catalytic action for the adsorption of Coomassie brilliant blue R250 dye (CBB) (50 mg/L, 25 mL), confirmed by the reduction in absorbance maxima that is time dependent. A remarkable adsorption of CBB (94.79%) was attained within 120 min, and the results were best-suited PSO and Elovich models with adsorption kinetic constant of 5.96E−04 g/mg.min and 37.81 mg/g.min, respectively. Further the toxicity studies of brilliant blue R250 dye and metabolite of CBB (post nano-remediated dye solution) was carried out on Vigna radiata (green gram) germination and growth. OTAuAgNPs as nanocatalyst remediated water revealed that it was nontoxic. Thus an ecofriendly and cost-effective approach for bimetallic nanoparticle synthesis could be further explored for removal of CBB from wastewater effluents.

Keywords: Biosynthesis; Bimetallic nanoparticles; Core–shell; OTAuAgNPs; Brilliant blue R250; Adsorption kinetics; Toxicity

Full paper is available at

DOI: 10.1007/s11696-022-02299-6


Chemical Papers 76 (10) 6487–6497 (2022)

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