Two-Wavelength, Photo-Initiation and Photo-Inhibition Competing for Selective Photo-Patterning of Hydrogel Porous Microstructures

Ever since its development, tissue engineering has played a significant role in the medical arena with an ever-growing demand for various tissue donations. One crucial factor in conducting in vitro tissue engineering study is the construction of a desirable artificial three-dimensional (3D) hydrogel tissue scaffold to act as the extracellular matrix (ECM), meeting the complex requirements for specific cell cultures. Existing hydrogel scaffold fabrication techniques and systems utilized in constructing ECM are either twodimensionally limiting, hard to control the pattern morphologies or expensive and time consuming. In the present study, we introduce a simple, inexpensive method for selective patterning 3D porous microstructures. This technique-'two wavelength photo-initiation and photo inhibition competes’ is an extension of conventional photo-patterning method. Integrating with shadow mask, photo inhibition radicals were introduced to couple with the polymerization chains and terminate the photo crosslinking behavior at designed region, making 3D selectively patterning hydrogel feasible. High aspect ratio ridge with selectively inhibited porous structures and selectively patterned micro pillar were fabricated using this method within 1 minute. The in vitro cell test results indicate the patterned structures' good biocompatibility.