During the elution study, all tubes were incubated in a heating block kept at 37 °C. A sample of fresh PBS (unexposed to the gels) was kept and defined as time point = 0. At each pre-determined time point, 500 µL of the PBS was aspirated from each sample and replaced with 500 µL fresh PBS (prewarmed to 37 °C). Samples were stored at -20 °C until samples from all time points had been collected. Quantification of the dexamethasone concentration of each sample was performed using HPLC, as described below.