Developing α-lipoic acid-derived solvent-free bioadhesives via deep eutectic melting

Solvent-free molten adhesives normally have high adhesion strength, which are widely used in industry but rare in medicine. Developing molten adhesives with medical potential is attractive. Herein, based on the positive therapy effect of α -lipoic acid (LA) and its significant feature of producing adhesives, a family of LA-derivatives containing terminal hydroxyl groups are synthesized and used to establish a serious of room-temperature molten LA-derived adhesives via deep eutectic strategy. The number of hydroxyl groups and molecular structure significantly affect the deep eutectic behavior and further affect the solidification and subsequent mechanical properties of the molten adhesives. The molten deep eutectic LA-derived adhesives can be applied to wounds and quickly cured under ultraviolet irradiation, forming tight and stable adhesion on moist or greasy tissue surfaces without the need for additional surface pretreatment. In vivo evaluation shows the deep eutectic adhesive successfully sealed gastric perforation that bridged by the regenerated mucosa. Besides the room temperature molten adhesives, LA-derivative with more quantity of terminal hydroxyl groups afforded a structural adhesive with strength equivalent to that of conventional adhesives. The deep eutectic behavior of LA and its derivatives provides a new perspective for the development of various types of LA-based adhesives.