Antibacterial activity of Mg 1-x Ni x O(x¼0.5) nano-solid solution; experimental and computational approach M. Qammar a , Z. Malik a, d, * , F. Malik b , T. Baig c , Abdul J. Chaudhary d a Department of Chemistry, School of Natural Sciences, National University of Sciences & Technology, H-12, Islamabad, 44000, Pakistan b Research Center for Modeling & Simulation, National University of Science & Technology, H-12, Islamabad, 44000, Pakistan c Atta-Ur-Rahman School of Applied Sciences and Biotechnology, National University of Science & Technology, H-12, Islamabad, 44000, Pakistan d Institute of Environment, Health and Societies, Brunel University London, Uxbridge, UB8 3PH, UK article info Article history: Received 13 July 2018 Received in revised form 19 October 2018 Accepted 10 November 2018 Available online 12 November 2018 Keywords: Bio inorganic chemistry Nanostructures Mg 1-x Ni x O(x¼0.5) nano-solid solution Antibacterial activity Computational studies abstract A wet chemical route was followed for the synthesis of Mg 1-x Ni x O (x ¼ 0.5) nano-solid solution. The nanoparticles were characterized by using PXRD, SEM and EDX analytical techniques. The nano particles were crystallized in NaCl structure type with crystallite size range; 10e30 nm with spherical geometry and average particle size range; 54e63 nm for the materials annealed at 500, 600 and 800  C, respec- tively. Antibacterial activities of the materials were investigated and compared against E. Coli and MRSA via disc diffusion method with respect to the surface O 2 and particle size. DFT studies were carried out for structural and geometric analysis of Mg 1-x Ni x O slab using Generalized Gradient Approximation (GGA). Energetic behavior of the compound was determined by band gap and density of state (DOS) at the same level of theory. Molecular docking studies of the material with bacterial DNA revealed spon- taneity of the reaction depicting highest binding strength with DNA in case of MgNiO dimer. © 2018 Published by Elsevier B.V. 1. Introduction Certain bacteria are the causative agent of most of the water- borne diseases. The major reason behind this issue is the increase in urbanization and anthropological activities [1]. At present nano- materials have numerous applications in every field like agricul- ture, biomedicine, environmental, biotechnology and electronics [2e6], e.g. metal oxides like MgO, ZnO, CaO and NiO are research target as ceramic-based antibacterial agents [7e9]. MgO [10] and NiO [11] show antibacterial activity in small amounts and in the absence of light. There are two major factors responsible for the antibacterial action of such materials; the generation of super oxide ion (O 2 ) and increase in pH of suspensions [12]. The solid solution has enhanced antibacterial activity as compared to pure MgO up- till now Zn x Mg 1-x O[13] and Ni x Mg 1-x O (x ¼ 0.05, 0.10, 0.20, 0.50 and 0.80) [14] bulk solid solutions are studied in this regard. NiO and MgO show 100% solid solubility in the bulk form due to the comparable atomic radii i.e. Mg 2þ ¼ 0.670 and Ni 2þ ¼ 0.650 Å [15]. According to our literature survey the MgNiO has been synthesized and studied mostly in form of thin films and there is very little literature available for MgNiO nanoparticles [15e19]. The antibacterial potential of various oxides such as CaO, MgO and ZnO [20] has been studied but the antibacterial applications of MgNiO solid solution in the nano dimension have not been studied yet. Effect of temperature on composition and the antibacterial activity of bulk Mg 1-x Ni x O has been studied by T. Ohira [14]. The present study intends to investigate the inhibition poten- tials of the Mg 1-x Ni x O solid solution nanomaterials against gram positive and gram negative bacteria, along with the thermal effect on the size and composition of nanoparticles. Finally, it aims on computational studies for the optimization of geometry, energetics and molecular docking to see the antibacterial activity of the ma- terial in order to verify the experimental results. 2. Methods 2.1. Experimental studies 2.1.1. Material preparation The precursors with 99.99% purity; Ni (NO 3 ) 2 $6H 2 O (BDH Chemicals Ltd.), Mg(NO 3 ) 2 $6H 2 O, ethylene glycol (Sigma Aldrich) and NaOH (Merck Millipore) were used for synthesis via sol-gel * Corresponding author. Department of Chemistry, School of Natural Sciences, National University of Sciences & Technology, H-12, Islamabad, 44000, Pakistan. E-mail address: zahida.malik@sns.nust.edu.pk (Z. Malik). Contents lists available at ScienceDirect Journal of Molecular Structure journal homepage: http://www.elsevier.com/locate/molstruc https://doi.org/10.1016/j.molstruc.2018.11.040 0022-2860/© 2018 Published by Elsevier B.V. Journal of Molecular Structure 1179 (2019) 347e353