New Visible-Light Photoinitiating System for Improved Print Fidelity in Gelatin-Based Bioinks

Abstract

Oxygen inhibition is a phenomenon that directly impacts the print fidelity of 3D biofabricated and photopolymerized hydrogel constructs. It typically results in the undesirable physical collapse of fabricated constructs due to impaired cross-linking, and is an issue that generally remains unreported in the literature. In this study, we describe a systematic approach to minimizing oxygen inhibition in photopolymerized gelatin-methacryloyl (Gel-MA)-based hydrogel constructs, by comparing a new visible-light initiating system, Vis + ruthenium (Ru)/sodium persulfate (SPS) to more conventionally adopted ultraviolet (UV) + Irgacure 2959 system. For both systems, increasing photoinitiator concentration and light irradiation intensity successfully reduced oxygen inhibition. However, the UV + I2959 system was detrimental to cells at both high I2959 concentrations and UV light irradiation intensities. The Vis + Ru/SPS system yielded better cell cyto-compatibility, where encapsulated cells remained >85% viable even at high Ru/SPS concentrations and visible-light irradiation intensities for up to 21 days, further highlighting the potential of this system to biofabricate cell-laden constructs with high shape fidelity, cell viability, and metabolic activity.

Composite Biomaterials as Long‐Lasting Scaffolds for 3D Bioprinting of Highly Aligned Muscle Tissue

“…The dramatic effect on shape fidelity by using I2959 (Figure b) could be also attributed to oxygen inhibition in the polymerization system, as has been recently published . Lim et al.…”

Highly Elastic Biodegradable Single-Network Hydrogel for Cell Printing

“…Some publications have reported that materials with water absorption from 78% (PEG-alginate hydrogel) to 1183% (GelMA/collagen hydrogel) were acceptable for printing. 20,40−42 However, the optimal hydrogel water absorption rates for printing and cell growth are often opposing. 43,44 No strong evidence exists to show that such water absorption ranges were good for cell culture.…”

Recent Advances in Bioink Design for 3D Bioprinting of Tissues and Organs

“…For extrusion-based printing, alginate is printed as a viscous solution, and the constructs are exposed to CaCl 2 solution to induce post-printing cross-linking. Alginate is not cell adhesive, thus it is generally blended with other natural polymers (e.g., gelatin and fibrinogen) to induce cell adhesion and biological activity (Xu et al, 2009; Jia et al, 2014; Yu et al, 2014; Lim et al, 2016; Pan et al, 2016). Note that, the majority of the natural polymers are used as a component of bioink formulation.…”

“…Lim et al (2016) recently reported a visible light photo-cross-linking system to minimize the oxygen inhibition in photopolymerized GelMA hydrogels. They reported higher print fidelity and cell viability for ruthenium/sodium persulfate visible photo-initiator as compared to UV photo-initiator Igracure 2959.…”