Heat-Assisted Digital Light Processing of Bioactive Tough PEG Hydrogels with Complex 3D Structure

Abstract

Digital light processing (DLP) of poly(ethylene glycol) (PEG) hydrogels with high mechanical toughness represents a long-standing challenge in the 3D printing field. Here, we report a 3D printing approach for the high-resolution manufacturing of structurally complex and mechanically strong PEG hydrogels via heat-assisted DLP. Instead of using aqueous solutions of photocrosslinkable monomers, PEG macromonomer melts were first printed in the absence of water, resulting in bulk PEG networks. Then, post-printing swelling of the printed networks was achieved in water, producing high-fidelity 3D hydrogels with complex structures. By employing a dual-macromonomer resin containing a PEG-based macrophotoinitiator, “all-PEG” hydrogel constructs were produced with compressive toughness up to 1.3 MJ.m-3. By this approach, porous 3D hydrogel scaffolds with trabecular-like architecture were fabricated, and the scaffold surface supported cell attachment and the formation of a monolayer mimicking bone-lining cells. This study highlights the promises of heat-assisted DLP in hydrogel fabrication, which may accelerate the development of 3D tissue-like constructs for regenerative medicine.

Photocuring 3D Printing of Hydrogels: Techniques, Materials, and Applications in Tissue Engineering and Flexible Devices

“…Within the realm of 3D printing hydrogels, poly(ethylene glycol) diacrylate (PEGDA) and dimethacrylate (PEGDMA), along with PVA-MA have emerged as principal representatives, extensively investigated for their utility. [92] Despite the commercialization of low-molecular-weight ethylene oxide (EO) chain monomers (e.g., 200, 400, and 600), classified as "UV monomers," PEGDA/PEGDMA, particularly those with higher molecular weights (>1000), are encompassed within this category. [32,93,94] Drawing inspiration from PEG, the PEG-PPG-PEG chain (Pluronic F127) is also modified to provide both ideal rheological behaviors required for direct ink writing and photocrosslinking of living structures.…”

“…[171] B) Synthesis of 4♦-BAPO-PEG. [92] C) The two-photon initiators with 𝜋-conjugated system (blue), electron donor (red), and water-soluble group (purple).…”

“…Right:The radical polymerization reaction of acrylamide by the hydroxyl radicals [171]. B) Synthesis of 4♦-BAPO-PEG [92]. C) The two-photon initiators with 𝜋-conjugated system (blue), electron donor (red), and water-soluble group (purple).…”

Photoclick Phase-separating Hydrogels for 3D Cell Culture and Volumetric Bioprinting

“…The developed phase-separating resins could be applicable to several fields of research. Besides VBP, the bioresin may find applications in other lightbased 3D printing such as digital light processing (DLP) 35,36 , extrusion printing 37,38 and twophoton direct laser writing 20,26,39 . Using light as the trigger, different pore sizes may be digitally 3D-printed within one object by tuning the light intensity and PIPS.…”

Architected Hydrogels for Functional Tissue Engineering Applications

“…Although it is compatible with multiple materials and various cell types, the major drawback is the limited printing resolution (150-500 µm). 93 Therefore, when it comes to printing anatomically shaped 3D structures, light-based 3D printing methods [94][95] are highly desirable.…”