Development of an affordable extrusion 3D bioprinter equipped with a temperature-controlled printhead

Bioprinters show great promise as enablers of regenerative medicine and other biomedical engineering applications. In this work, we present a flexible and costeffective design for a do-it-yourself bioprinter capable of printing/bioprinting gelatin methacryloyl (GelMA) and Pluronic constructs at flow rates of 0.05-0.1 mL/min and effective resolutions of 500-700 mu m. The most distinctive feature of this bioprinter is its ability to control the rheology of bioinks simply by adjusting the extrusion temperature during printing. This is achieved by circulating temperature-controlled water within the printhead, which is engineered as a single 3D-printed component consisting of a water-recirculation jacket surrounding the ink/bioink cartridge. The flexibility to circulate either warm or cold water allows the system to be adapted according to the needs dictated by the bioink composition. Herein, we demonstrate the ability to control the printability of GelMA or Pluronic fibers by decreasing or increasing the temperature, respectively, thereby regulating its viscosity. In addition, any commercial needle with a Luer lock can be incorporated into the printhead, allowing the easy fabrication of fibers of different diameters with a single printhead. We showed that our bioprinter is capable of printing simple 2D constructs with high fidelity (i.e., lines of GelMA with a thickness of similar to 522 +/- 36.83 mu m can be printed at linear speeds of 100 mm min(-1)) and 3D constructs composed of as many as five layers of cell-laden 5% GelMA. We also demonstrated that C2C12 cells bioprinted through needle tips (300 mu m in diameter) exhibit adequate post-printing viability (similar to 90%), as well as spreading after 7 days of culture. The presentation of this bioprinter may contribute appreciably to the expansion of bioprinter use due to its low overall cost of manufacture, flexibility and open-source character, amenability to modification and adaptation for use with different 3D-printed printheads, and ability to bioprint using GelMA.