NIR-induced polymerization triggered by upconversion nanoparticles

Abstract

3D printing technology based on photopolymerization reaction is widely exploited to construct scaffolds for tissue-engineering. There are numerous techniques to produce biocompatible polymer structures, meanwhile almost all of them utilize the high energy excitation, which causes cell photodamade and limits the penetration depth of the initiating light. The possible solution to avoid such disadvantages is the transfer to the low energy photopolymerization activation from near-infrared (NIR) region. This approach reduces the phototoxicity and significantly increases the photocuring depth.
Upconversion nanoparticles (UCNP) with core/shell structure β-NaYF4:Yb3+/Tm3+@ NaYF4 are promising NIR photopolymerization triggers. UCNPs convert NIR light (980 nm) into ultraviolet (345, 360 nm), visible (450, 475, 645 nm) and NIR (800 nm) irradiation due to multistep nonlinear optical processes. The UCNP incorporation in photocurable composition (PCC) provide the polymerization activation under NIR light when UCNP photoluminescence bands fall within the absorption bands of photoinitiator .
In this work we developed the PCC based on PEG-DA oligomer which is capable to mix with both hydrophilic and hydrophobic components. This made it possible to simplify the PCC preparation procedure, to escape the UCNP surface modification step, and to increase the number of PI utilized. We also demonstrated the possibility to include both highly hydrophilic biopolymers (modified hyaluronic acid) capable to undergo the reaction of photo cross-linking and water insoluble PI (Irgacure 369) simultaneously. In vitro assay showed no cytotoxicity of obtained polymer structures.
This work was supported by the Russian Science Foundation (Project No. 18-79-10198)


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Polina A. Demina
Federal Scientific Research Center «Crystallography and Photonics» of RAS
Russia

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