# Thiol-ene photo-click collagen-PEG hydrogels: impact of water-soluble photoinitiators on cell viability, gelation kinetics and rheological properties

Source: [Thiol-ene photo-click collagen-PEG hydrogels: impact of water-soluble photoinitiators on cell viability, gelation kinetics and rheological properties](<https://www.sota2.com/research/paper/68fa35d51e209131ce8a4eef>)

Collection index: [llms.txt](<https://www.sota2.com/research/llms.txt>)

Data updated: 2025-10-24T21:29:46.381Z

Authors: Roisin Holmes, Xuebin B Yang, Aishling Dunne, Larisa Florea, David Wood, Giuseppe Tronci

Published: 2017-06-09T17:05:36.000Z

## Abstract

Thiol-ene photo-click hydrogels were prepared via step-growth polymerisation using thiol-functionalised type-I collagen and 8-arm poly(ethylene glycol) norbornene terminated (PEG-NB), as a potential injectable regenerative device. Type-I collagen was thiol-functionalised by a ring opening reaction with 2-iminothiolane (2IT), whereby up to 80 Abs% functionalisation and 90 RPN% triple helical preservation were recorded via 2,4,6-Trinitrobenzenesulfonic acid (TNBS) colorimetric assay and circular dichroism (CD). Type, i.e. 2-Hydroxy-1-\[4-(2-hydroxyethoxy)phenyl\]-2-methyl-1-propanone (I2959) or lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP), and concentration of photoinitiator were varied to ensure minimal photoinitiator-induced cytotoxicity and to enable thiol-ene network formation of collagen-PEG mixtures. The viability of G292 cells following 24 h culture in photoinitiator-supplemented media was largely affected by the photoinitiator concentration, with I2959-supplemented media observed to induce higher toxic response compared to LAP-supplemented media. In line with the in vitro study, selected photoinitiator concentrations were used to prepare thiol-ene photo-click hydrogels. Gelation kinetics proved to be largely affected by the specific photoinitiator, with LAP-containing thiol-ene mixtures leading to significantly reduced complete gelation time with respect to I2959-containing mixtures. Other than the specific photoinitiator, the photoinitiator concentration was key to adjust hydrogel storage modulus (G'), whereby 15-fold G' increase was observed in samples prepared with 0.5% (w/v) compared to 0.1% (w/v) LAP. The photoinitiator-gelation-cytotoxicity relationships established in this study will be instrumental to the design of orthogonal collagen-based niches for regenerative medicine.

## Recorded benchmark results

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## Original sources and implementation

[Original paper](<https://arxiv.org/abs/1706.03043>)

[PDF](<https://arxiv.org/pdf/1706.03043.pdf>)