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Synthesis of nanoparticles and their interaction with bacteria

Student name: Ms Prarthana Khurana
Guide: Dr Udit Soni
Year of completion: 2018
Host Organisation: Special Centre for Nano Science, Jawaharlal Nehru University, New Delhi
Supervisor (Host Organisation): Dr Pratima R. Solanki
Abstract: Nanotechnology is the study of nanoparticles which possess unique physical and chemical properties when compared to their respective bulk materials. The interactions of these nanomaterials with various microorganisms are found to be selectively toxic towards different strains of bacteria and hence they have been exploited for their antibacterial activities. In the present study, nanoparticles i.e. silver, copper and zinc oxide were synthesized and characterized by UV-Vis spectrophotometry, Dynamic Light Scattering technique and X-ray diffraction technique and the antibacterial activity of these nanoparticles were studied on pathogenic bacteria. The toxicity of these nanoparticles was studied on gram negative E. coli and gram positive S. aureus and S. scuiri. The antibacterial assays of these synthesized metal and metal oxide NPs were carried out in both nutrient broth as well as nutrient agar medium against all three bacteria. The bacterial growth was monitored in the presence of nanoparticles of different concentrations, determined by the MIC analysis, to examine the toxicity of NPs. It was observed that growth of gram negative bacteria E. coli was inhibited by AgNPs and CuNPs at a concentration of 80μg/ml, 40μg/ml respectively, while ZnO NPs at 700μg/ml was observed to inhibit very less in the case of E. coli and S. aureus. The growth of gram positive S. aureus was inhibited by slightly higher concentrations of AgNPs, CuNP at 120μg/ml, 60μg/ml respectively. However, the growth of the fast growing gram positive bacteria S. sciuri was observed to be inhibited at comparatively lower concentrations, as compared to other two bacteria, of AgNP, CuNP and ZnO NP at 60μg/ml, 40μg/ml and 550μg/ml respectively. Collectively, these experiments demonstrate the selective toxic nature of ZnO NPs to different strains of bacteria.

Key words: Nanoparticles, Bacteria, Antibacterial activity, Specificity, Nanoparticles-cell interaction