Aspiration-assisted bioprinting for precise positioning of biologics

Three-dimensional (3D) bioprinting is an appealing approach for building tissues; however, bioprinting of minitissue blocks (i.e., spheroids) with precise control on their positioning in 3D space has been a major obstacle. Here, we unveil "aspiration-assisted bioprinting (AAB)," which enables picking and bioprinting biologics in 3D through harnessing the power of aspiration forces, and when coupled with microvalve bioprinting, it facilitated different biofabrication schemes including scaffold-based or scaffold-free bioprinting at an unprecedented placement precision, similar to 11% with respect to the spheroid size. We studied the underlying physical mechanism of AAB to understand interactions between aspirated viscoelastic spheroids and physical governing forces during aspiration and bioprinting. We bioprinted a wide range of biologics with dimensions in an order-of-magnitude range including tissue spheroids (80 to 600 mu m), tissue strands (similar to 800 mu m), or single cells (electrocytes, similar to 400 mu m), and as applications, we illustrated the patterning of angiogenic sprouting spheroids and self-assembly of osteogenic spheroids.