Toxicological Analysis of Silver Nanoparticles and Colistin coated AgNp using Drosophila as a model organism” Dr. Ravish H Assistant Professor, Department of Neurochemistry NATIONAL INSTITUTE OF MENTAL HEALTH AND NEURO SCIENCES (INSTITUTE OF NATIONAL IMPORTANCE), BANGALORE, INDIA * Introduction Nanomaterials have intense application in the field of medicine and have the capability to transform basic science into novel products. Like almost all Nanoparticles, Silver Nanoparticles (AgNp’s) have extreme advantage in molecular, cellular, physiological process and have unique antimicrobial properties. Whereas, Colistin have been re emerged as a powerful antibiotic and have therapeutic effects on Multidrug resistant bacteria. Hence the study aimed at novel approach of evaluating the toxic effects of AgNp and Colistin coated AgNp at lower concentration using Drosophila melanogaster as a model organism Objectives The present study aims at In-vivo analysis and evaluation of Toxicity of Silver Nanoparticles (AgNp) and Colistin coated AgNp in adult flies of wild type Drosophila melanogaster. Results Conclusion References 1. S. Parasuraman (2011). “Toxicological screening.” J Pharmacol Pharmacother. Apr-Jun; 2(2): 2. Abdellatif et al. (2016). “Efficacy and toxicity of aerosolised colistin in ventilator-associated pneumonia: a prospective, randomised trial.” Annals of Intensive Care 6:26 3. Liangpeng Ge, Qingtao Li, Meng Wang, Jun Ouyang, Xiaojian Li, and Malcolm MQ Xing (2014). “Nanosilver particles in medical applications: synthesis, performance, and toxicity.” Int J Nanomedicine. 9: 2399–2407 Materials and methods Preparation of Growth Media for Fly The standard food containing corn flour, common sugar, yeast, agar and Propianic acid was prepared at the normal room temperature for the growth of wild type Drosophila melanogaster Dosages of AgNp /Colistin/Colistin-AgNp The physical and chemical methods of synthesizing AgNp will induce toxic effects hence AgNp of size nm, synthesized from tyrosine by green technology methods was used. AgNp of concentration 0.2mM was used as a stock solution and the toxic levels of different dosages ranging from 1×10 -2 mM, 2×10 -2 mM, 3×10 -2 mM, 4×10 -2 mM, 4×10 -3 mM and 2×10 -3 mM were evaluated respectively. Assessing the Survival Rate of Drosophila Both AgNp and Colistin coated AgNp treated flies were allowed to grow at normal room temperature and the survival rate of adult flies was evaluated for the period of 168 hrs on regular interval of 24 hrs by LD50 Assay[1]. The LD50 was used as an indicator of acute toxicity Assessment of Toxic Dosages of AgNp and Colistin coated AgNp Based on the Analysis, the concentration at which the rate of survival was less were determined to be the Toxic dosage and the dose where Survival rate was high were concluded to be Non Toxic dosage. The results were interpreted for both AgNp and Colistin coated AgNp.  In recent years Silver Nanoparticles have huge application in medical and healthcare industry due to its unique Physiochemical properties such as antibacterial, antifungal, antiviral, and anti-inflammatory activity [3].  Our results have proven that at lower dosage of colistin coated AgNP’s are biocide and non toxic to the Survival, Reproductive health and Mobility.  Further in vitro studies can be carried out since this would be a revolutionary approach to overcome antibiotic resistance and in the treatment of various neurological disease since they are biocide and non toxic to the survival of living organism. Observation Silver Nanoparticles (AgNp) was less toxic up to 4×10 -2 mM, since the survival rate was ≥ 60% and non toxic at lower concentration since the rate was high ≥80% Similarly in Colistin coated AgNp the survival rate was ≥ 80% up to 1×10 -3 mM and it was almost 100 % at lower concentration up to 3×10 -4 mM In contrary to the study Raj A et al.,[2], AgNps showed high reproductive health and Survival rate in Drosophila melanogaster which indicates that the toxicity of Silver Nanoparticles was less in lower concentration. The study inferred that the Survival Rate, Reproductivity and Mobility of D.melanogaster was comparatively higher in Colistin coated AgNp than in AgNp which indicates the lesser toxicity of Colistin coated AgNp.