Silk fibroin aerogels for drug delivery applications

•Silk fibroin aerogels are synthesized using sol–gel and supercritical CO2 technology.•SF aerogels are loaded with ∼21wt% of ibuprofen using supercritical CO2.•Greater than 99.98wt% of ibuprofen is in the amorphous form.•The ibuprofen release from SF aerogels occurs over a period of 6h.•Release of ibuprofen from SF aerogels is governed by Fickian diffusion. Silk fibroin (SF) is a natural protein, derived from the Bombyx mori silkworm. Silk fibroin based porous materials are being extensively investigated for biomedical applications, due to their biocompatibility and biodegradability. The results presented here demonstrate the potential of SF aerogels as drug delivery devices for the extended release of ibuprofen, a candidate drug. SF aerogels are loaded with of ibuprofen using supercritical carbon dioxide (scCO2) at 40°C and 100bar. Differential scanning calorimetry of the ibuprofen-loaded SF aerogels indicates that the ibuprofen is amorphous. Scanning electron microscopy and nitrogen adsorption/desorption analysis are used to investigate the morphology and textural properties. Phosphate buffer solution (PBS) soaking studies, at 37°C and pH 7.4, reveal that SF aerogels do not swell nor exhibit any weight loss for up to 6h, the lifetime of the release measurements performed in the present study. In vitro ibuprofen release in PBS, at 37°C and pH 7.4, occurs over a 6-h period when the ibuprofen is loaded in SF aerogel discs that are 1.4cm in diameter and 0.85cm in height. In contrast, the dissolution of the same amount of pure ibuprofen occurs in 15min. Furthermore, the release of ibuprofen from these SF aerogel discs are modeled using the Ritger–Peppas model which indicates that ibuprofen release follows Fickian diffusion.