(−)-Riboflavin (vitamin B2) and flavin mononucleotide as visible light photo initiators in the thiol–ene polymerisation of PEG-based hydrogels†
The photoinitiators used in light mediated hydrogelation have been limited due to cytotoxicity and solubility issues. Here we report the use of riboflavin and flavin mononucleotide as nontoxic, naturally occurring photoinitiators for the thiol–ene hydrogelation of functionalised poly(ethylene glycol). High Resolution Magic Angle Spinning (HRMAS) NMR spectroscopy and oscillatory rheometry were used to probe the efficiency of these initiators for this hydrogel system. The gelation and reaction progression could easily be manipulated using different initiator concentrations and light intensities.