Effective Photoinitiating Systems Using Citric Acid-Derived Chromophores as Photosensitizers for 3D Bio-Printing Applications

The growing interest in the use of naturally derived compounds, associated with the increasing focus on green chemistry principles in various fields of chemical technology, is also evident in the development of light-cured resins for 3D printing. Therefore, in this work, four fluorophores formed alongside carbon dots as one of the products of the reaction between citric acid and specific β-amines were comprehensively studied. These studies facilitated the detailed optical characterization of the compounds, which in turn led to a better understanding of the electron transfer mechanisms accompanying the initiation of photopolymerization processes. In addition, cyclic voltammetry and photostability studies enabled a preliminary assessment of the applicability of the fluorophores as photosensitizers of commercially available diphenyl iodonium salts (SpeedCure 938®). FT-IR analyses and supporting photorheology measurements made it possible to determine the kinetics of the photopolymerization process and demonstrate the influence of the water content (non-reactive agent) on its course. Finally, it was possible to develop resins for 3D printing with low viscosity for use in the stereolithography (SLA) method and high viscosity for use in the direct ink writing (DIW) method enriched with light-curing of the finished pattern.随着化学技术各领域对绿色化学原则关注度的持续提升，天然来源化合物的应用热度日益攀升，这一趋势在3D打印用光固化树脂的研发中同样体现明显。鉴于此，本研究对柠檬酸与特定β-胺类反应的产物之一——与碳点（carbon dots）一同生成的四种荧光团（fluorophores）展开了全面研究。通过上述研究，研究人员得以对该类化合物开展细致的光学表征，进而更深入地理解光聚合过程引发时伴随的电子转移机制。此外，通过循环伏安法与光稳定性研究，研究人员可对该荧光团作为商用二苯基碘鎓盐（SpeedCure 938®）光敏剂的适用性进行初步评估。通过傅里叶变换红外光谱（FT-IR）分析与配套的光流变学（photorheology）测量，研究人员得以确定光聚合过程的动力学特性，并阐明非反应性试剂水含量对该过程进程的影响。最终，本研究成功开发出两类3D打印用光固化树脂：一类为低黏度树脂，适用于立体光刻（Stereolithography, SLA）工艺；另一类为高黏度树脂，适用于直写成型（Direct Ink Writing, DIW）工艺，且可对最终成型样件实施光固化后处理。