Formation of allyl carboxymethylcellulose (CMC-Allyl) hydrogel precursor solutions. Sodium CMC was functionalised with allyl groups using a protocol reported in the literature . The degree of allyl substitution was determined as 12% by 1 HNMR. A stock solution of allyl-functionalised CMC (CMC-Allyl) was prepared in PBS at pH 6.0 and stock solutions of poly(ethylene glycol) dithiol (PEGDT) and photoinitiator (Irgacure 2959) were prepared in PBS and ethanol, respectively. To the CMC-allyl solution, the PEGDT and Irgacure 2959 stock solutions were added to achieve a ratio of 1.2/1.0/0.1 between allyl/thiol/initiator moieties. The mixtures were mixed by vortexing, followed by centrifugation to eliminate bubbles formed.