24. CRITICAL IMPORTANCE OF NOZZLE TEMPERATURE TO BIOPRINT VASCULAR GRAFTS WITH SHEAR-THINNING HYDROGEL

Abstract Introduction The development of vascular grafts adapted to the nature of the patient and their treatment is constantly evolving. Fine control of the bioprinting manufacturing process is a key issue to obtain proper personalized vascular grafts. The aim is to check the influence of the nozzle temperature during bioprinting a Gelatin/Gellan Gum/Alginate hydrogel vascular grafts. Methods Vascular grafts were printed using a Gelatin/Gellan Gum/Alginate (8:3:0.5 %w/v) hydrogel in an BioX bioprinter with the printhead and bed set up to 65 °C. Two configurations were set: 1) a standard conical tip (nozzle) and 2) the same nozzle thermally insulated with aluminum foil to uniformly distribute the temperature. A temperature control using a 100 kΩ thermistor was performed in four points: chamber, nozzle, printhead, and bed. Four heating/cooling cycles were performed in each control point. Results The grafts printed with the standard nozzle exhibited irregular wall thickness and an uneven surface, attributed to lower temperatures in the conical tip. In contrast, results from the aluminum-covered nozzle indicated temperature distributions of 33.13±0.87, 49.03±3.92, 52.38±3.53, and 64.98±0.10 °C for chamber, nozzle, printhead, and bed, respectively. This improved temperature distribution enhanced the printability of Gelatin/Gellan Gum/Alginate vascular grafts, resulting in a more regular wall thickness and surface profile. Conclusion The optimization of temperature in the nozzle during the printing process is a critical parameter for bioprinting vascular grafts using this shear-thinning Gelatin/Gellan Gum/Alginate hydrogel.