Ionic liquid treated bacterial cellulose sheets as prospective biodegradable implant materials

The purpose of this research was to create bacterial cellulose (BC) membranes/sheets which can be degraded by the enzymes in body fluids on implantation for soft and hard tissue regeneration. BC has been explored for its use in hard and soft tissue regeneration such as bone, dental, wound, hernia, dura mater, skin, nerve, cornea, and blood vessels. The limiting factor in the use of BC as biomedical implant material is that it is practically non-biodegradable in vitro and in vivo. However, reactive hydroxyl groups on BC allow a variety of chemical modifications which can be beneficial for the development of smart degradable biomedical materials. The use of ionic liquids (IL) is the greener and non-toxic alternative to the chemical treatment for the degradation of BC. The IL affect the degradability of BC by interacting with the functional groups and decreasing its crystallinity. Two non-toxic and biocompatible IL i.e. Pyridinium hydrogen sulfate (Py-HSO 4 ) and 1-butyl-3-methyl imidazolium hydrogen sulfate (BMIM-HSO 4 ) were used in the current study. The biodegradation of BC using these IL has not been studied previously for biomedical implants. The characterizations of the IL treated BC were done using XRD, FTIR analysis, SEM, contact angle studies, degradation assay, drug delivery, and in vitro biocompatibility. SEM results suggest a clear change in the morphology of the BC nano fibers after treatment with ionic liquids. Furthermore, significant degradation was observed over 28 days where BC (Py-HSO 4 ) degraded by 36% and BC (BMIM-HSO 4 ) treated had degraded by 56%. Additionally, the IL treated BC could carry antibacterial drugs and showed potential for their sustained release. The modified membranes supported cell attachment and proliferation and were non-toxic and highly biocompatible. These results suggest that BC pellicles/sheets treated with IL can be used as a degradable implant material for tissue engineering, regeneration, and drug delivery for various regenerative biomedical applications. Graphical abstract