printability study of polyelectrolyte bioinks based on chitosan for 3dbioprinting applications

Shearthining bioinks are the best choices for application in extrusion-based bioprinting which is an emerging technology to create three-dimensional (3d) functional constructs for tissue engineering. electrostatic interaction due to the lack of toxicity is a desirable method for forming physical polyelectrolyte hydrogels. this study used chitosan nanoparticles with a positive charge as polycation and carboxymethyl chitosan with a negative dominant charge as polyanion to form the bioink. nanoparticles were made by the ionic gelation method and the final bioink was obtained by mixing a carboxymethyl chitosan solution and dispersed nanoparticles. changing the solution ph of two components was also studied. evaluation of the obtained nanoparticles was done by dls, sem, and zeta potential tests. according to the rheological studies and cell viability, the optimal sample was obtained from a combination of polymer dissolved in the alkaline medium and nanoparticles dispersed in a neutral medium. the printability of this bioink was investigated by studying the effect of nozzle diameter and print speed and applied flow. microscopic images of printed filaments were studied for uniformity in diameter with the help of imagej software and according to them, a needle with a size of 20g and a speed of 200 mm/min, and a volume flow rate of 0. 245 µl/s was selected as the optimal condition for printing.