High mechanical and self-healing carboxymethyl chitosan-hyaluronic acid hybrid hydrogel via multiple dynamic covalent bonds for drug delivery.

[Display omitted] • These hybrid hydrogels are synthesized via a "one-step" method without a toxic crosslinking agent. • These hybrid hydrogels have notable mechanical properties due to the interactions between multiple covalent bonds. • These hybrid hydrogels achieved excellent self-healing performance. • These hybrid hydrogels have pH responsiveness, good biocompatibility, high drug loading capacity, and sustained release behavior. Therapeutic drugs for human cardiovascular disease require specific carriers. Hydrogels have a porous structure, plasticity, and biocompatibility, and are ideal carriers for cardiovascular drugs. Moreover, for their intended functions, hydrogels also need to have high mechanical properties, self-healing properties, good pH-responsive performance, and other properties. Here, based on the interactions between multiple dynamic covalent bonds, we effectively synthesized hybrid hydrogels of carboxymethyl chitosan (C-CS), aldehyde-modified hyaluronic acid (OHA), polyvinyl alcohol (PVA), and boric acid (BA). The multiple covalent bonds reinforce each other, endowing the hydrogels with high mechanical properties, self-healing properties and pH responsiveness. In addition, the whole preparation process does not require crosslinking agents and the operation process is simple. The results show that the 5% PVA + C-CS + OHA + BA hydrogel has high mechanical properties (tensile stress 40.07 KPa; compressive stress 553.38 KPa), good self-healing performance (up to 92%) and excellent pH responsive performance. In addition, the hydrogel has high drug-loading capacity (117.54 mg/g) and sustained-release performance. In conclusion, this hybrid hydrogel can potentially be used as a drug carrier for clinical treatment. [ABSTRACT FROM AUTHOR]