Drop-on-demand bioprinting: A redesigned laser-induced side transfer approach with continuous capillary perfusion

We present a drop-on-demand (DOD) bioprinting method based on a novel implementation of laser-induced side transfer (LIST). Our approach involves continuous bioink perfusion through a glass capillary featuring a laser-machined hole in the capillary wall, serving as a nozzle. Focused low-energy nanosecond laser pulses are employed for precise droplet ejection. This innovative design separates the control of the bioink flow rate inside the capillary from the printing rate (drop ejection), leading to an enhanced printing workflow. We assessed the impact of key printing parameters, such as laser energy and flow conditions, on printing quality. Furthermore, we utilized the redesigned LIST to bioprint human umbilical vein endothelial cells (HUVECs). Our findings indicate that the printed HUVECs exhibit no viability loss and demonstrate the ability to recruit perivascular cells, including pericytes and fibroblasts. The redesigned LIST can be utilized in tissue engineering applications requiring DOD cell printing.