Ionic Carbazole-Based Water-Soluble Two-Photon Photoinitiator and the Fabrication of Biocompatible 3D Hydrogel Scaffold

• Published in: ACS applied materials & interfaces Vol. 13; no. 24; pp. 27796 - 27805
• Main Authors: Gao, Wen, Chao, Hao, Zheng, Yong-Chao, Zhang, Wei-Cai, Liu, Jie, Jin, Feng, Dong, Xian-Zi, Liu, Yan-Hong, Li, Shu-Jing, Zheng, Mei-Ling
• Format: Journal Article
• Language: English
• Published: American Chemical Society 23.06.2021
• Subjects: Biological and Medical Applications of Materials and Interfaces; water-soluble photoinitiator; 3D hydrogel scaffold; host−guest interaction; biocompatibility; carbazole derivative; two-photon polymerization
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.1c02227

Two-photon polymerization of a three-dimensional (3D) hydrogel structure has been widely applied in biological tissue engineering. For improving the biocompatibility of hydrogel structures, a new kind of ionic carbazole water-soluble photoinitiator was prepared to realize the fabrication of a 3D hydrogel structure in aqueous phase. 3,6-Bis­[2-(1-methyl-pyridinium)­vinyl]-9-methyl-carbazole diiodide (BMVMC) and cucurbit[7]­uril (CB7) have been employed to generate a complex with better water solubility by host–guest interactions. The binding ratio of the complex was demonstrated to be 1:1 through the characterization of isothermal titration calorimetry (ITC). The two-photon absorption (TPA) cross section of the complex increases to 2500 GM compared with the 750 GM of the BMVMC molecule. Then, an aqueous-phase photoresist was obtained using the CB7/BMVMC complex as the photoinitiator and poly­(ethylene glycol) diacrylate (PEGda) as the hydrogel monomer. Two-photon fabrication capability in aqueous phase has been studied using the as-prepared photoresist. A low laser threshold of 3.7 mW as well as a high resolution of 180 nm are achieved. Benefiting from the fluorescence properties of the photoinitiator, we can achieve the confocal fluorescence images without any assistance of fluorescent probes. Subsequently, a 3D engineered hydrogel scaffold microstructure was fabricated by the two-photon polymerization technology, whose biocompatibility was demonstrated by culturing the structure with living cells of L929. The BMVMC–CB7 complex and the as-prepared photoresist are demonstrated to have good biocompatibility, which is prospective for further application in tissue engineering.