¹Department of Pharmaceutical Biotechnology, Faculty of Pharmacy, Anadolu University, Eskişehir, Turkey DOI : 10.12991/jrp.2019.175 Gene therapy is generally defined as the transfer of genetic material to cells to treat a disease or at least improve the clinical condition of a patient. The most commonly used vectors in gene therapy are viral and non-viral vectors. The aim of this study was to develop a gene carrier system based on chitooligosaccharide-coated nanostructured lipidic nanoparticles and evaluate the physicochemical properties, such as zeta potential, particle size, SEM images, pH, cytotoxicity, DNA-binding properties, serum stability and transfection to cells. In this study, cationic formulations were produced using Dynasan® 116 and Transcutol ®P as a lipidic phase and chitooligosaccharide lactate for polymeric coating with DOTAP as a cationic agent. These formulations were made with the oil-in water hot emulsification technique. GFP was selected as the genetic material to be loaded into the formulations. According to the results, the chitooligosaccharide-coated cationic lipid nanoparticles prepared had considerably small particle sizes (144- 178 nm) and high zeta potential (+37.6/+33.7mV). Based on the MTT assay, the cytotoxic effect of formulations on the NIH 3T3, A549 and MDA-MB-231 cell lines exhibited a dose-time-dependant pattern. Further, the prepared formulations binded DNA effectively and protected DNA against the serum component. It was concluded that chitooligosaccharide-coated lipidic nanoparticle formulations can be prepared as a pDNA-nanoparticle complex and can be employed as a gene delivery system effectively. Keywords : Chitooligosaccharide lactate; lipidic nanocarrier; gene delivery; cytotoxicity; transfection