Biocompatible hydrogel adhesives with multifunctional properties, including injectability, fast self-healing, and suitable on-demand detachment, are highly desired for minimally invasive procedures, but such materials are still lacking. Herein, an injectable self-healing biocompatible hydrogel adhesive with thermoresponsive reversible adhesion based on two extracellular matrix-derived biopolymers, gelatin and chondroitin sulfate, is developed to be used as a surgical adhesive for sealing or reconnecting ruptured tissues. The resulting hydrogels present good self-healing and can be conveniently injected through needles. The strong tissue adhesion at physiological temperatures originates from the Schiff base and hydrogen bonding interactions between the hydrogel and tissue that can be weakened at low temperatures, thereby easily detaching the hydrogel from the tissue in the gelation state. In vivo and ex vivo rat model show that the adhesives can effectively seal bleeding wounds and fluid leakages in the absence of sutures or staples. Specifically, a proof of concept experiment in a damaged rat liver model demonstrates the ability of the adhesives to act as a suitable laparoscopic sealant for laparoscopic surgery. Overall, the adhesive has several advantages, including low cost and ease of production and application that make it an exceptional multifunctional tissue adhesive/sealant, effective in minimally invasive surgical applications.

No abstract

No abstract

In the present study, the morphological changes on a gold electrode during the oxygen reduction (ORR) and oxygen evolution reaction (OER) processes in a dimethyl sulfoxide (DMSO)-based electrolyte solution were investigated using an electrochemical atomic force microscope (EC-AFM) with the help of vibrational spectroscopy measurements. The growth of the ORR products on the electrode surface, which was mainly assigned to lithium peroxide (Li2O2), was directly confirmed by the EC-AFM. It was found that the water concentration in the solution significantly affects the morphology of the ORR products. The growth of anisotropic Li2O2 particles on the gold electrode surface has been confirmed to be an electrochemical process. No evidence was found to support the disproportionation growth mechanism. These ORR products were fully decomposed at a potential as high as 4.4 V (vs Li+/Li) in the subsequent OER process, more positive than that determined by a surface-enhanced Raman spectroscopy (SERS) measurement. Combined with infrared absorption spectroscopy and SERS measurements, we propose that the oxidation decomposition of the Li2O2 deposits first occurs at its interface with the gold electrode surface, while that of the remaining particles takes place at a higher overpotential. On the contrary, the ORR deposits could be fully decomposed at a potential as low as 3.6 V when tetrathiafulvalene (TTF) was included in the solution. We confirmed by EC-AFM that the electrochemically generated TTF+ can mediate the decomposition of the Li2O2 at a lower potential through a homogeneous oxidation mechanism.

No abstract