Hydrogel Degradation Behavior Evaluation

The degradation behaviour of the hydrogels was evaluated by measuring wet weight of the hydrogels (weight of the water-absorbed gel after the excessive fluid is removed from the gel) over time in phosphate buffered saline (PBS, pH 7.4). Hydrogels (10 mg) were placed in polypropylene conical tubes (Cole-Parmer Instrument Company LTD, Eaton Socon, UK), each containing either 5 mL PBS or 5 mL PBS containing 1.5 mg/mL lysozyme. The PBS solutions were replaced with fresh solutions daily. This ensured active lysozyme was present in the media [70 (link),87 (link)]. The hydrogel sample and solution were sealed and maintained at 37 °C with mild agitation (50 rpm) for the duration of the study. Chitosan-free inorganic hydrogels (GLMS hydrogel) (10 mg) prepared by dissolving 0.1 g GLMS in 1mL water at 10 wt% were used for comparison. Inductively coupled plasma atomic emission spectroscopy (ICP-AES, PerkinElmer, Waltham, MA, USA) was used to obtain the soluble silica release profiles in PBS solution and high-performance liquid chromatography (HPLC, Shimadzu, Wolverton, UK) was used for the quantification of glycerol and glucose in degradation solutions. Experiments were performed in triplicates [102 (link),103 (link)].