*Corresponding Author Address: Dr. Ali Shihab Ahmed, University of Al-Nahrian, College of Biotechnology, Baghdad, Iraq, E.mail: dralishihabahmed@gmail.com World Journal of Pharmaceutical Sciences ISSN (Print): 2321-3310; ISSN (Online): 2321-3086 Published by Atom and Cell Publishers © All Rights Reserved Available online at: http://www.wjpsonline.org/ Original Article Characterization of synthesized carboxymethylnanochitosan loaded with streptomycin and testing its in vitro anticancer activity Muna Mohammed Khayri, Ali Shihab Ahmed* College of Science, Department of Biotechnology, University of Al-Nahrian, Baghdad, Iraq Received: 25-03-2017 / Revised: 08-05-2017 / Accepted: 23-05-2017 / Published: 27-05-2017 ABSTRACT This study aims to synthesize carboxymethylnanochitosn (CMNC) from synthetic nanochitosan (NC) which was produced from chitosan and encapsulated streptomycin(S) then characterized and bioassayed. A quantity of 2 mg of chitosan was selected for nanochitosan synthesis. Maximum absorbance (Ȝmax) was determined for streptomycin (S), CMNC and CMNC-S were 280, 265 and 270 nm, respectively. The loading efficiency of CMNC with S was 90%. Fourier transform-infrared (FTIR) spectroscopy for CMNC and CMNC-S showed that absorption peaks at the same frequencies 3000 -3800 cm -1 with the change in stretching of the absorption percent, which increased sharply. Scanning electron Microscope (SEM) of chitosan, NC, CMNC and CMNC-S showed aggregation of CMNC and entrapment of S nanoparticles within CMNC. Results of atomic force microscope (AFM) images and analysis illustrated that the concentration 2mg/ 100 ml of soluble chitosan recorded a diameter 54.64 nm and the insoluble chitosan at the same concentration resulted in 105.52 nm. According to the process of CMNC preparation, the nanoparticles size achieved 35 nm. After loading CMNC with S, the average of the nanoparticles increased to 37 nm. Results confirmed the loading process of CMNC with S. Particle size distribution showed median particle size of CMNC recording 770 nm and for CMNC-S was 526 nm. The concentration 50μg/ml of CMNC-S reached 37.5% growth inhibition (GI%) against rhabdomyosarcoma (RD) cell line in comparison with 38.5% GI for streptomycin (100μg/ml) after 24 hrs of incubation. Keywords: Nanochitosan derivatives, Streptomycin, Encapsulation, Cell- line, Growth inhibition% INTRODUCTION The efficacy of many drugs is often limited by their potential to reach the site of therapeutic action due to various problems such as low lifetime, poor bioavailability, in vivo low stability, solubility, intestinal absorption problems, therapeutic effectiveness, side effects, and exceed the safe therapeutic concentrations. In most cases, only a small amount of administered dose reaches the target site, while the majority of the drug distributes throughout the rest of the body in accordance with its physicochemical and biological properties [1]. Streptomycin (S) is bactericidal antibiotic drug under aminoglycosides group and produced from Streptomyces griseus [2]. It is known to have toxic effects causing nephrotoxicity and neuroparalysis [3]. Nanotechnology applications in drug delivery systems have opened up new possibilities in direct- targeted effect and release of drugs [4]. Continuous release of drug can be achieved by encapsulating the active ingredient in a polymer matrix, thus, the dose and frequency of administration would be reduced [5-6]. Chitosan is a polyaminosaccharide with many significant biological like biodegradable, biocompatible, bioactive and chemical properties. All of these properties make chitosan and its derivatives widely used in many biomedical fields [7]. Carboxymethylated chitosan has received more attention because of its good water solubility especially low molecular weight, and it is convenient to be applied in medicine and pharmaceutics because of their ability to fit the neutral environment of the human body [8,9]. Carboxymethylchitosan (CMC) is prepared by means of carboxymethylation, as some of the –OH groups of chitosan were substituted by –CH2COOH groups. Therefore, the reactive ligands such as – COOH and –NH2 groups are still amenable to chemical modifications to improve its physical properties for metal chelation and dye binding [10].