Light-based 3D printed biomaterials with tunable properties using biosourced photoinitiators

Light-based 3D printing is a promising additive manufacturing technique for fabricating engineered tissue mimics that recapitulate the complex architecture of biological tissues. This type of 3D printing relies on photopolymerization, which is a process that provides inherent spatial and temporal control and thus makes resolving features on meso- and micro-scales possible. However, several barriers limit the use of light-based 3D printing in biomedical applications. Firstly, few photoinitiators, the light-absorbing molecules that drive the polymerization reaction, are cytocompatible. Secondly, it is unknown how material properties such as Young’s modulus and swelling can be modulated using printing parameters. In this work, we use direct light processing (DLP) and two photon polymerization (TPP) and two model monomers—a combinatory hydroxyethyl methacrylate and urethane dimethacrylate or 6-hexanediol diacrylate—to assess the efficacy of a novel biosourced photoinitiator system (PhInS) comprised of curcumin and N-phenyl glycine. We compare its efficacy to the commercial photoinitiator, Irgacure 369, which is a known endocrine disruptor. Additionally, we extracted the Young’s modulus (stiffness) from TPP structures to study how printing parameters influence final material properties. Through our work, we found our novel PhInS can be used for both DLP and TPP. Further, we established key relationships between printing parameters through linear and non-linear regression models. For DLP, we found that as light intensity increased, needed exposure time decreased. A similar connection was identified for TPP, where increased laser power allowed for higher scanning speeds (the inverse of exposure time). We also found that for TPP structures, changing the laser power or scanning speed changes the stiffness of the polymerized materials, with increased laser power leading to less stiff materials while increased scanning speed led to stiffer materials. Together, we show the capabilities of biosourced photoinitiators for light-based 3D printing and how altering printing parameters allows for the creation of tunable materials. This work lays groundwork for the development of precisely controlled photomanufactured tissue mimetics, without the use of toxic materials.