Direct cell encapsulation is a powerful tool for fabrication of biomimetic 3D cell culture models in vitro. This method allows more precise recapitulation of the natural environment and physiological functions of cells compared to classical 2D cultures. In contrast to seeding cells on prefabricated scaffolds, cell encapsulation offers benefits regarding high initial cell loading, uniformity of cell distribution and more defined cell–matrix contact. Two-photon polymerization (2PP) based 3D printing enables the precise engineering of cell-containing hydrogel constructs as tissue models. Two-photon initiators (2PIs) specifically developed for this purpose still exhibit considerable cyto- and phototoxicity, impairing the viability of encapsulated cells. This work reports the development of the first cleavable diazosulfonate 2PI DAS, largely overcoming these limitations. The material was characterized by standard spectroscopic methods, white light continuum two-photon absorption cross-section measurements, and its photosensitization of cytotoxic singlet oxygen was compared to the well-established 2PI P2CK. When DAS is used at double concentration to compensate for the lower two-photon cross section, its performance in 2PP-printing of hydrogels is similar to P2CK based on structuring threshold and structure swelling measurements. PrestoBlue metabolic assay showed vastly improved cytocompatibility of DAS in 2D. Cell survival in 3D direct encapsulation via 2PP was up to five times higher versus P2CK, further demonstrating the excellent biocompatibility of DAS and its potential as superior material for laser-based biofabrication.

中文翻译：

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生物相容性重氮磺酸盐引发剂，可通过双光子聚合直接封装人干细胞†

直接细胞封装是体外仿生3D细胞培养模型制造的强大工具。与经典2D培养相比，此方法可以更精确地概括自然环境和细胞的生理功能。与在预制支架上播种细胞相比，细胞包封在初始细胞载量高，细胞分布均匀性和更明确的细胞-基质接触方面具有优势。基于双光子聚合（2PP）的3D打印可将包含细胞的水凝胶构造物作为组织模型进行精确工程设计。专为此目的开发的双光子引发剂（2PI）仍然表现出相当大的细胞毒性和光毒性，从而损害了被囊化细胞的生存能力。这项工作报告了第一个可裂解的重氮磺酸盐2PI DAS的开发，大大克服了这些局限性。该材料通过标准光谱学方法进行了表征，白光连续光子的两个光子吸收截面测量，并将其对细胞毒性单线态氧的光敏性与公认的2PI P2CK进行了比较。当以双倍浓度使用DAS来补偿较低的双光子横截面时，基于结构化阈值和结构溶胀测量，其在2PP打印水凝胶中的性能类似于P2CK。PrestoBlue代谢测定法显示DAS在2D模式下的细胞相容性大大提高。3D直接封装中的细胞存活率 基于结构化阈值和结构溶胀度的测量，其在水凝胶2PP印刷中的性能与P2CK相似。PrestoBlue代谢测定法显示DAS在2D模式下的细胞相容性大大提高。3D直接封装中的细胞存活率 基于结构化阈值和结构溶胀度的测量，其在水凝胶2PP印刷中的性能与P2CK相似。PrestoBlue代谢测定法显示DAS在2D模式下的细胞相容性大大提高。3D直接封装中的细胞存活率与P2CK相比，通过2PP加工的材料最多可提高5倍，这进一步证明了DAS的出色生物相容性及其作为激光生物制造的优良材料的潜力。