RESEARCH PAPER Positively charged biopolymeric nanoparticles for the inhibition of Pseudomonas aeruginosa biofilms Laura Chronopoulou . Enea Gino Di Domenico . Fiorentina Ascenzioni . Cleofe Palocci Received: 26 April 2016 / Accepted: 28 September 2016 Ó Springer Science+Business Media Dordrecht 2016 Abstract Currently, many microbial infections have the potential to become lethal owing to the develop- ment of antimicrobial resistance by means of different mechanisms and mainly on the basis of the fact that many drugs are unable to reach therapeutic levels in the target sites. This requires the use of high doses and frequent administrations, causing adverse side effects or in some cases toxicity. The use of nanoparticle systems could help overcome such problems and increase drug efficacy. In the present study, we developed a new drug delivery system based on the use of biopolymeric nanovectors loaded with tobra- mycin (Tb), which is the standard antibiotic for the treatment of Cystic Fibrosis-associated P. aeruginosa lung infections. Tb-loaded biopolymeric nanoparticles composed by dextran sulfate (DS) and chitosan (CS) were prepared by ionotropic gelation. We optimized drug entrapment in DS/CS nanoparticles, obtaining particles of 170 nm and with a drug loading of 400 lg Tb/mg of nanoparticles. In accord with in vitro release experiments, such preparations were able to release approximately 25 % of their cargo in 60 h. In vitro, the antimicrobial efficacy of the drug delivery system on P. aeruginosa biofilm was tested and compared to the effects of free drug revealing that this formulation can reduce the viability of P. aeruginosa biofilms for 48 h with a single-dose administration. Keywords Pseudomonas aeruginosa Á Nanoparticles Á Biofilm Á Cystic fibrosis Á Tobramycin Introduction Bacterial infections can result in chronic states, in which colonization develops into a biofilm. Bacterial biofilms are complex three-dimensional communities of cells surrounded by a self-produced extracellular polymeric matrix that confers high tolerance to conventional antimicrobial treatments and to immune responses (Flemming and Wingender 2010; WHO 2014). Biofilms account for approximately 80 % of all human infections and are involved in a wide variety of diseases, including cystic fibrosis (Pruss et al. 2002; Høiby et al. 2010). During progression of cystic fibrosis (CF) lung disease, the majority of patients becomes infected with P. aeruginosa (Gibson et al. Laura Chronopoulou and Enea Gino Di Domenico have contributed equally to the work. L. Chronopoulou Á C. Palocci (&) Department of Chemistry, University of Rome La Sapienza, Rome, Italy e-mail: cleofe.palocci@uniroma1.it E. G. Di Domenico Department of Clinical Pathology and Microbiology, San Gallicano Institute, IRCCS, Rome, Italy F. Ascenzioni Department of Biology and Biotechnology C. Darwin, University of Rome La Sapienza, Rome, Italy 123 J Nanopart Res (2016)18:308 DOI 10.1007/s11051-016-3611-y