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Investigation on characterization and biomedical properties of silver nanoparticles synthesized by an actinobacterium Streptomyces olivaceus (MSU3)

Sanjivkumar, M., Vaishnavi, R., Neelakannan, M., Kannan, D., Silambarasan, T., Immanuel, G.
Biocatalysis and agricultural biotechnology 2019 v.17 pp. 151-159
2,2-diphenyl-1-picrylhydrazyl, Fourier transform infrared spectroscopy, Streptococcus pneumoniae, Streptomyces olivaceus, absorption, anti-inflammatory activity, antibacterial properties, antioxidant activity, growth retardation, hydroxyl radicals, inhibitory concentration 50, ions, nanosilver, nitric oxide, particle size, silver, silver nitrate
This investigation was carried out to biosynthesize silver nanoparticles (AgNPs) from a marine actinobacterium Streptomyces olivaceus (MSU3), characterized its physical features and also evaluated its biomedical properties. Initially, AgNPs was produced by reduction of silver nitrate by using the selected actinobacterium under laboratory condition, followed by, the AgNPs was characterized using standard procedures. In FT-IR analysis, the biosynthesized AgNPs showed six major groups (C=C-H, ROH, C=N-OH, C-C, R-NH2 and RCOOH) in between the wavenumber 455.20 and 3294.42 cm−1 and it expressed strong signal (3 keV) at silver region, which confirmed the formation of elemental silver by the reduction of silver ions with the absorption range of 450 nm. This biosynthesized AgNPs revealed spherical in shape and the particle size of 12.3 nm with the 2θ values of 38.12 – 77.41°. The antibacterial property of different concentrations of AgNPs was tested against clinical bacterial strains and it expressed maximum (23.0 mm) growth inhibition against Streptococcus pneumoniae at the highest concentration (30 µl) with the MIC and MBC values of 0.625 and ≤ 2.5 µg/ml respectively. Finally the in-vitro anti-inflammatory and antioxidant properties of AgNPs were assessed. It expressed the highest (97.53%) percentage inhibition of in-vitro anti-inflammatory activity at 500 µg/ml concentration as well as the maximum in-vitro total antioxidant activity (60.38%), DPPH activity (58.73%), reducing power effect (52.73%), hydroxyl radical scavenging activity (51.03%) and nitric oxide scavenging activity (45.86%) were recorded at 100 µg/ml concentration of AgNPs with the respective IC50 values of 178.9, 52.31, 74.11 89.89 and 155.5 µg/ml. From the results, it could be considered that the biosynthesized AgNPs of S. olivaceus (MSU3) has biomedical applications with antibacterial, anti-inflammatory and antioxidant properties.