1 Scientific RepoRts | 6:24929 | DOI: 10.1038/srep24929 www.nature.com/scientificreports polysaccharide-capped silver Nanoparticles inhibit bioflm formation and eliminate multi- drug-resistant bacteria by disrupting bacterial cytoskeleton with reduced cytotoxicity towards mammalian cells sridhar sanyasi 1,* , Rakesh Kumar Majhi 2,* , Satish Kumar 1 , Mitali Mishra 2 , Arnab Ghosh 3 , Mrutyunjay Suar 1 , Parlapalli Venkata Satyam 3 , Harapriya Mohapatra 2 , Chandan Goswami 2 & Luna Goswami 1 Development of efective anti-microbial therapeutics has been hindered by the emergence of bacterial strains with multi-drug resistance and bioflm formation capabilities. In this article, we report an efcient green synthesis of silver nanoparticle (AgNP) by in situ reduction and capping with a semi- synthetic polysaccharide-based biopolymer (carboxymethyl tamarind polysaccharide). The CMT-capped AgNPs were characterized by UV, DLS, FE-SEM, EDX and HR-TEM. These AgNPs have average particle size of ~20–40 nm, and show long time stability, indicated by their unchanged SPR and Zeta-potential values. These AgNPs inhibit growth and bioflm formation of both Gram positive (B. subtilis) and Gram negative (E. coli and Salmonella typhimurium) bacterial strains even at concentrations much lower than the minimum inhibitory concentration (MIC) breakpoints of antibiotics, but show reduced or no cytotoxicity against mammalian cells. These AgNPs alter expression and positioning of bacterial cytoskeletal proteins FtsZ and FtsA. CMT-capped AgNPs can efectively block growth of several clinical isolates and MDR strains representing diferent genera and resistant towards multiple antibiotics belonging to diferent classes. We propose that the CMT-capped AgNPs can have potential bio-medical application against multi-drug-resistant microbes with minimal cytotoxicity towards mammalian cells. Infections caused by pathogenic bacteria have become a serious health and economic problem 1 . Tere has been constant decrease in efectiveness of antibiotics mainly due to unregulated use of antibiotics, leading to the devel- opment of multi-drug-resistant (MDR) bacterial strains 2,3 . Terefore, it has become necessary to search for alter- native healthcare approaches to mitigate the problem of bacterial infections and contaminations. Typically, the bacterial infections can be categorised into two types, namely acute infection and chronic infections. Te former, however are treated efectively by the development of modern vaccines, antibiotics and infection control meas- ures 4 . However, the other type of infections has accentuated the infection related complications and therefore has poised a major challenge in controlling infection related issues 4 . Moreover, the treatment of acute infections have become difcult because the infection related diseases have been supplemented by chronic infections caused by 1 School of Biotechnology, KIIT University, Patia, Bhubaneswar 751024, India. 2 School of Biological Sciences, national Institute of Science Education and Research, Institute of Physics Campus, Sachivalaya Marg, Bhubaneswar 751005, India. 3 Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005, India. * These authors contributed equally to this work. Correspondence and requests for materials should be addressed to C.G. (email: chandan@niser.ac.in) or L.G. (email: lbh_1975@yahoo.co.in) Received: 29 October 2015 accepted: 30 March 2016 Published: 29 April 2016 OPEN