Effects of Irgacure 2959 and lithium phenyl-2,4,6-trimethylbenzoylphosphinate on cell viability, physical properties, and microstructure in 3D bioprinting of vascular-like constructs

Abstract

Photocrosslinkable polymers such as gelatin methacrylate (GelMA) have various 3D bioprinting applications. These polymers crosslink upon exposure to UV irradiation with the existence of an appropriate photoinitiator. Two photoinitiators, Irgacure 2959 and lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) are commonly used. This study systematically investigates the effects of photoinitiator types on the cell viability, physical properties, and microstructure in 3D bioprinting of GelMA-based cellular constructs. The main conclusions are: (1) during the 3D bioprinting, the cell viability generally decreases as the photoinitiator concentration and printing time increase using both Irgacure 2959 and LAP. At the low photoinitiator concentrations (such as 0.3% and 0.5% (w/v)), the overall cell viability is good within the printing time of 60 min using both Irgacure 2959 and LAP. However, at the high photoinitiator concentrations (such as 0.7% and 0.9% (w/v)), the overall cell viability using LAP is much higher than that using Irgacure 2959 within the printing time of 60 min; (2) after the 3D bioprinting, the photoinitiator types, either Irgacure 2959 or LAP, have negligible effects on the post-printing cell viability after crosslinking; (3) after the 3D bioprinting, GelMA samples cured with Irgacure 2959 have slightly larger pore size, faster degradation rate, and greater swelling ratio compared to those cured with LAP; (4) 3D GelMA-based vascular-like constructs have been fabricated using dynamic optical projection stereolithography, and the measured dimensions have been compared with the designed dimensions showing good shape fidelity.

Green Synthesis of Novel GelMA/Carboxymethyl Chitosan Hydrogels and Evaluation of Their Properties for Potential Biomedical Applications

“…Heqi et al evaluated the effect of Irgacure 2959 on cell viability. The results of this study demonstrated the signi cant cytotoxicity of this photoinitiator at 0,5% (w/v) concentration and more [40]. Additionally, another problem of most conventional UV photoinitiators such as Irgacure 2959 is insolubility in water due to the presence of the aromatic group in their molecule.…”

In Vitro Strategies to Vascularize 3D Physiologically Relevant Models

“…In the field of vascularization, the most used photoinitiators are Irgacure 2959 (maxi-mum efficiency wavelength 275 nm) and lithium phenyl-2,4,6trimethylbenzoylphosphinate (LAP, maximum efficiency wavelength 375 nm), the latter being the less cytotoxic one. [174,177] Depending on the light source to cure the polymers, vat photopolymerization can be classified in stereolithography (SLA) (polymer cured with a laser), digital light processing (DLP) (polymer cured with a projector), and continuous digital light processing (CDLP)/continuous liquid light processing (CLIP) (polymer cured with oxygen and light emitting diodes (LEDs)). [174,178] Definitions and Relevant Parameters in Bioprinting: Definitions are given to differentiate between cell-loaded bioinks, hereinafter "bioinks," and acellular bioinks that will be named "biomaterial bioinks," according to Groll et al [179] Most of bioinks are composed of one or several materials, other than cells, being the number of studies using a material-free approach very small, as described in Section 4.3.2.…”

“…In the field of vascularization, the most used photoinitiators are Irgacure 2959 (maximum efficiency wavelength 275 nm) and lithium phenyl‐2,4,6‐trimethylbenzoylphosphinate (LAP, maximum efficiency wavelength 375 nm), the latter being the less cytotoxic one. [ 174 , 177 ]…”

Advances in Photocrosslinkable Materials for 3D Bioprinting

“…Introduction of methacryloyl groups endows GelMA with feasible photocrosslinkable property. GelMA has been the most frequently used and commercially available biomaterial for 3D bioprinting since the first report by Van Den Bulcke et al [58,[69][70][71][72][73] For example, GelMA is used as the photocrosslinkable ink for DIW and 3D projection stereolithography, resulting in controllable mechanical properties and biological functions of printed scaffolds. [74,75] Initiators play an important role in controlling the gelation kinetic, mechanical properties, and cell viability in photocrosslinkable systems.…”