Contents lists available at ScienceDirect Biocatalysis and Agricultural Biotechnology journal homepage: www.elsevier.com/locate/bab Investigation on characterization and biomedical properties of silver nanoparticles synthesized by an actinobacterium Streptomyces olivaceus (MSU3) M. Sanjivkumar a , R. Vaishnavi a , M. Neelakannan a , D. Kannan a , T. Silambarasan b , G. Immanuel c, ⁎ a Department of Microbiology, K. R. College of Arts and Science, K.R. Nagar, Kovilpatti 628503, Tamilnadu, India b Department of Microbiology, Periyar University, Salem 636011, Tamilnadu, India c MNP Laboratory, Centre for Marine Science and Technology, Manonmaniam Sundaranar University, Rajakkamangalam 629502, Tamilnadu, India ARTICLE INFO Keywords: Streptomyces sp Bacterial pathogens Silver nanoparticles Antioxidant XRD ABSTRACT 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 la- boratory 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-NH 2 and RCOOH) in between the wavenumber 455.20 and 3294.42 cm -1 and it expressed strong signal (3 keV) at silver region, which con- firmed 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%) per- centage 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 IC 50 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. 1. Introduction Nanotechnology is a fast growing branch of science that deals with synthesis and development of various nano-materials, which are being prepared by copper, zinc, titanium, magnesium, gold, alginate and silver (Husseiny et al., 2015). It is a rapid, upcoming, multidisciplinary promising area that has an influence in medical, food, agricultural, electronic and industrial fields, where they manufacture materials at the nano scale (ranging between 1 and 100 nm in size) (Basavaraj et al., 2012). The nanoparticles can be prepared by employing physical, chemical or biological methods. Generally, the physical method has low yield and the chemical method cause contamination due to precursor chemicals, use of toxic solvents and the generation of hazardous by- products (Wang et al., 2007). Hence, there is a growing need to use eco- friendly, safe, reliable and clean method for the preparation of nano- particles that does not produce toxic wastes in their process synthesis protocol (Husseiny et al., 2015; Balakumar and Prakash, 2016a). Silver nanoparticles (AgNPs) are extensively used among all nano- materials, therefore biological and biomimetic approaches to synthesize silver nanoparticles are under research (Abdel Rahim et al., 2017). AgNPs became the main focus of intensive study because of its wide selection of applications in the areas like catalyst, optics, anti- microbials, anti-oxidants and biomaterial production (Qin et al., 2011; Emmanuel et al., 2017). Biological approaches such as bacteria espe- cially actinobacteria, fungi, yeast and plants can be used for production of nanoparticles like AgNPs, which exhibited different biological ac- tivities like antibacterial (Qin et al., 2011), anti-oxidant (Balagurunathan et al., 2011) and anti-cancer (Składanowski et al., https://doi.org/10.1016/j.bcab.2018.11.014 Received 31 August 2018; Received in revised form 4 November 2018; Accepted 17 November 2018 ⁎ Corresponding author. E-mail address: gimmas@gmail.com (G. Immanuel). Biocatalysis and Agricultural Biotechnology 17 (2019) 151–159 Available online 19 November 2018 1878-8181/ © 2018 Elsevier Ltd. All rights reserved. T