The selection of photoinitiators for photopolymerization of biodegradable polymers and its application in digital light processing additive manufacturing

Abstract

Digital light processing additive manufacturing (DLP-AM) technology has received a lot of attention in the field of biomedical engineering due to its high precision and customizability. However, some photoinitiators, as one of the key components in DLP-AM, may present toxicity and limit the application of DLP-AM toward biomedical applications. In order to gain further insights into the correlation between biocompatibility and photoinitiators in photoresins, a study on the selection of photoinitiators used in DLP-AM is conducted. The light absorbance range and cytocompatibility of four photoinitiators, vitamin B2 combined with triethanolamine (B2/TEOA), diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), 2-dimethoxy-2-phenylacetophenone (DMPA), and 2-hydroxy-4-(2-hydroxyethoxy)-2-methylpropiophenone (I2959), are characterized. Each photoinitiator is then combined with poly(glycerol sebacate) acrylate (PGSA) and poly(εcaprolactone) diacrylate (PCLDA), to evaluate their miscibility and film formation ability through photopolymerization. The mechanical properties, in vitro and in vivo biocompatibility studies on bulk films are investigated. It is found that B2/TEOA and TPO exhibit a wider light absorbance range than I2959 and DMPA.PGSA films with B2/TEOA (PGSA-B2/TEOA) is capable of sustaining cell proliferation up to 10 days and showing low immune responses after 14 days post implantation, proving its biocompatibility. Although B2/TEOA requires longer photopolymerization time, the mechanical strength of PGSA-B2/TEOA is comparable to PGSA films with TPO and DMPA, and this combination is 3D-printable through DLP-AM at the rate of 100 s per layer. In summary, B2/TEOA is a promising photoinitiator for 3D printing.

Projection-based 3D printing of multichannel poly(caprolactone) methacrylate nerve guidance conduit for peripheral nerve regeneration

“…The photorheological properties of PCLMA must be evaluated before the PBP procedure. 24 The temperature at which the material is applied considerably influences the printing outcome of the scaffold. Print defects and potential failures resulting from inappropriate viscosity are attributable to unsuitable temperatures.…”

Influence of Process Parameters on the Characteristics of Additively Manufactured Parts Made from Advanced Biopolymers

“…Lists of photo-reactive biopolymers and their photo-initiators can be found elsewhere [ 105 , 108 , 109 ]. In addition to the biocompatibility standards, total or partial solubility in water [ 108 ] and absorption spectra in the UV A range (315–400 nm) or visible light (400–700 nm) are other basic requirements of a photo-initiator used for biomedical applications [ 110 ]. The quantity of photo-initiator in the photopolymer resin is also a significant parameter; by varying this parameter, the absorption spectra of photo-initiators may be changed.…”

3D printing by stereolithography using thermal initiators

“…Few approaches were suggested to meet the need for an efficient water-soluble PI by synthesis of salts 13 , 14 and nanoparticles 15 , 16 . However, the toxicity of the PIs is debatable, and the production process is expensive in both approaches 17 . Photopolymerization in water under NIR light is challenging due to the lack of such water-soluble commercial PIs, and their synthesis involves expensive materials 18 , 19 .…”