Digital Light Processing-based Bioprinting with Composable Gradients.

Recapitulation of complex tissues signifies a remarkable challenge and, to date, only few approaches have emerged that can efficiently reconstruct necessary gradients in three-dimensional (3D) constructs. This is true even though mimicry of these gradients is of great importance to establish the functionality of engineered tissues and devices. Here, a composable-gradient digital light processing (DLP)-based (bio)printing system is developed for the first time, utilizing the unprecedented integration of a microfluidic mixer for the generation of either continual or discrete gradients of desired (bio)inks in real time. Notably, the precisely controlled gradients are composable on-the-fly by facilely adjusting the (bio)ink flow ratios. In addition, this setup is designed in such a way that no washing steps are needed when exchanging the gradient (bio)inks, further enhancing our time- and (bio)ink-saving strategy. Various planar and 3D structures exhibiting continual gradients of materials, of cell densities, of growth factor concentrations, of hydrogel stiffness, and of porosities in horizontal and/or vertical direction, are exemplified. The composable fabrication of multifunctional gradients strongly support the potential of our unique bioprinting system in numerous biomedical applications. This article is protected by copyright. All rights reserved.