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Abstract: Rapid and accurate visible-light photopolymerization is essential for advancing bioprinted engineered tissues. In this study, we developed a novel three-component photoinitiator system for visible light-induced crosslinking of gelatin methacryloyl (GelMA) hydrogels, designed to improve polymerization kinetics, mechanical strength, and structural integrity. Incorporation of 2-bromoacetophenone (BAP) considerably accelerated photopolymerization, with reaction rates increasing alongside BAP concentration, enabling the rapid fabrication of stable hydrogel scaffolds. Printing experiments confirmed that BAP promoted fast crosslinking of GelMA bioinks under visible light, reducing printing time while preserving high-resolution structural features. Additionally, the incorporation of BAP induced microscale structural transformations in the hydrogels during hydration, as evidenced by scanning electron microscopy imaging and swelling analyses. This unique property enabled the fabrication of multilayer constructs exhibiting time-dependent deformation, demonstrating four-dimensional (4D) printing capabilities. Moreover, biocompatibility evaluations revealed that cells maintained high viability in BAP-containing hydrogels. Overall, the BAP-based photoinitiator system offers a promising strategy for high-speed, high-resolution bioprinting, combining enhanced mechanical performance, reduced fabrication time, and dynamic structural adaptability—features that make it highly suitable for advanced biofabrication and tissue engineering applications.

Novel bromoacetophenone-accelerated visible-light 3D and 4D printing methods for rapid fabrication of biocompatible and structurally dynamic scaffolds

快速且高精度的可见光光聚合技术是推动生物打印工程化组织发展的关键基础。 本研究构建了一种新型三组分光引发体系, 用于可见光诱导甲基丙烯酰化明胶 (gelatin methacryloyl, GelMA) 水凝胶的交联反应, 以提升聚合动力学性能、 力学强度及结构稳定性。 通过引入2-溴代乙酰苯(2-bromoacetophenone, BAP), 显著加快了光聚合反应速率, 且反应速率随 BAP 浓度增加而进一步提升, 从而实现了稳定水凝胶支架的快速制备。 打印实验结果表明, 在可见光照射下, BAP 可促进 GelMA 生物墨水的快速交联, 在缩短打印时间的同时保持了高分辨率的结构特征。 此外, 在水合过程中, BAP 的引入诱导水凝胶发生微尺度结构转变。 扫描电子显微镜成像与溶胀行为分析结果证实了该结构演变。 基于这一特性, 研究进一步构建了具有时间依赖性形变行为的多层结构, 实现了四维 (4D) 打印功能。 生物相容性评价结果显示, 在含 BAP 的水凝胶体系中细胞仍保持较高存活率。 综上所述, 基于 BAP 的光引发体系为高速、 高分辨率生物打印提供了一种具有潜力的技术策略。 该体系兼具增强的力学性能、 缩短的制备时间以及结构动态可调性, 为先进生物制造与组织工程应用提供了新的技术路径。
Gelatin methacryloyl (GelMA); Bioink; Photoredox; Visible light crosslinking; Digital light processing (DLP) rapid three-dimensional (3D) bioprinting; Four-dimensional (4D) bioprinting