Synthesis and Mechanical Characterization of Chitosan Threads for Biomedical Applications I. Rodriguez, O. Rivera-Debernardi, A. Rosillo, I. Delgadillo-Holtfort, J. Delgado * University of Guanajuato, Sciences and Engineering Division, Mexico isefer_10@hotmail.com, jorgedel@dci.ugto.mx Abstract. Chitosan is a biopolymer widely used for many applications, especially in the biomedical field, due to its interesting properties like excellent sorption capability, biodegradability and biocompatibility. The presence of reactive groups in the structure of this biopolymer makes possible the attachment of different molecules. In this study a chitosan thread is synthesized, using a microfluidic technique with two merging channels of acidic chitosan and hydroxide, in order to use it as a controlled release device of drugs. Varying the flows of the fluids in the channels is possible to control the diameter of the thread, obtaining samples of medium and high molecular weight for each flow rate used in the synthesis. The obtained thread of chitosan was mechanically characterized performing tensile tests until failure and stress relaxation tests. An optical system of polarizers was set to visualize the alignment of the polymeric chains while the material is elongated during the tensile test. Young modulus is obtained for each type of sample to quantify the stiffness of the material, and relaxation times were calculated to observe the viscoelastic behavior. Alignment of the material was confirmed, since birefringence was shown. Keywords: chitosan, thread, microfluidic, mechanical properties, birefringence. 1 Introduction Chitosan is a lineal copolymer composed of repetitive units of D-glucosamine, which is the predominant unit, and N-acetyl-glucosamine linked by β-(1-4) glycosidic bonds (Fig. 1) [1]. Chitosan is obtained from partial deacetylation of chitin, which is found in the exoskeleton of crustaceans, insects and the cell wall of fungi [2]. The presence of the functional groups amino on C(2) and hydroxyl on C(3), C(6) in the structure of chitosan provides a material with interesting properties like excellent sorption capability, biocompatibility [3], biodegradability. Besides, it is hemostatic, antifungal and antimicrobial agent [1]. These properties allow the processing of the polymer into various geometries as nanoparticles, microparticles, scaffolds, sponges, hydrogels, beads and threads [4]. Some of the applications of the geometries enunciated are as wound dressing, tablet excipient [5], controlled release of drugs [6], gels with antibiotics [7] and gene, protein or peptide entrapment and delivery [11]. The methods * Corresponding authors: Isela F. Rodriguez Cabrera, Jorge Delgado. 15 ISSN 1870-4069 Research in Computing Science 148(1), 2019 pp. 15–23; rec. 2018-08-22; acc. 2018-10-22