Title: Biogenic nanosilver inhibits Mycobacteria using nitrate reductase assay

Authors: Adebayo J. Bello; Luqman A. Adams; Nneka N. Onyejepu; Justice I. Igbinehi; Omoboyede F. Igbari; Joy Okpuzor

Addresses: Department of Cell Biology and Genetics, University of Lagos, Yaba, Lagos, Nigeria; Material and Nanochemistry Laboratory, Department of Chemistry, University of Lagos, Yaba, Lagos, Nigeria ' Material and Nanochemistry Laboratory, Department of Chemistry, University of Lagos, Yaba, Lagos, Nigeria ' Center for Tuberculosis Research (CTBR), Nigeria Institute of Medical Research, Yaba, Lagos, Nigeria ' Material and Nanochemistry Laboratory, Department of Chemistry, University of Lagos, Yaba, Lagos, Nigeria ' Material and Nanochemistry Laboratory, Department of Chemistry, University of Lagos, Yaba, Lagos, Nigeria; College of Nanoscience and Technology, Soochow University, Jiangsu Province, China ' Department of Cell Biology and Genetics, University of Lagos, Yaba, Lagos, Nigeria

Abstract: Nanosilver was synthesised by bioreduction using aqueous extracts of Moringa oleifera (MO-AgNPs) leaf and Allium cepa bulb (AC-AgNPs) as reducing and capping agents. The nanosilver was characterised with UV/vis, FT-IR, and SEM-EDX. Microbiological activity on five Mycobacteria strains: ATCC 35882, ATCC 25177, Mycobacterium other than tuberculosis (MOTT), Mycobacterium fortuitum and multi drug resistance M. tuberculosis (MDR-MTB) was investigated using nitrate reductase assay (NRA). Results obtained for UV/vis gave absorption maxima at 430 nm for MO-AgNPs and 440 nm for AC-AgNPs. FT-IR showed functional groups associated with the biomolecular capping agents. SEM showed the nanosilver formed aggregates spherical and/or in oval shape with smooth surface. EDX spectra exhibited the presence of elemental silver. Minimum inhibitory concentration (MIC) study for both nanosilver against Mycobacteria indicated a higher inhibitory activity for MO-AgNPs over the AC-AgNPs. Herein, we have reported the first biosynthesised nanosilver activity against Mycobacteria using NRA. Nanosilver may therefore be developed as nanoaerosol for targeted and effective treatment of Mycobacteria infections.

Keywords: Mycobacteria; tuberculosis; nanosilver; biosynthesis; Moringa oleifera; Allium cepa; nitrate reductase assay; NRA; MO-AgNPs; AC-AgNPs; minimum inhibitory complex.

DOI: 10.1504/IJNBM.2019.101758

International Journal of Nano and Biomaterials, 2019 Vol.8 No.2, pp.129 - 145

Received: 09 Jan 2018
Accepted: 20 Jul 2018

Published online: 26 Aug 2019 *

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