Reduced Thermal Damage Achieved by High-Conductivity Hydrogel in RF Energy Tissue Welding

Radiofrequency (RF) tissue welding is an innovative tissue anastomosis technique that utilizes bioimpedance to convert electrical energy into thermal energy, enabling the connection and reconstruction of tissues via the denaturation and crosslinking of proteins. However, the high temperatures generated in this process often lead to excessive thermal damage to tissues, thereby adversely impacting cellular activity and impeding tissue repair in practical applications. In this study, we developed a polyacrylamide/alginate (PAAm/Alg) hydrogel with high ionic conductivity (16.8 ± 1.2 S/m) achieved by introducing Ca²⁺ for the purpose of reducing thermal damage in RF tissue welding. The PAAm/Alg-Ca²⁺_0.5M hydrogel possessed excellent mechanical properties with a stress of 315.6 ± 14.1 kPa and an elongation of 382.7 ± 89.0%. Additionally, the hydrogel exhibited a high water content (83.7 ± 0.3%) and excellent stability of swelling property in water. In addition, the hydrogel extract showed good biocompatibility with no significant adverse effects on cell activity in the cytotoxicity test. At last, we conducted ex vivo experiments to investigate the effectiveness of the hydrogel as a cooling agent during RF tissue welding. The result showed that the maximum temperature was effectively reduced from 137.9 ± 4.7 to 101.8 ± 2.5 °C, while the strength of the anastomotic stoma (12.0 ± 3.2 kPa) was not affected by the intervention of this hydrogel. Histological analysis also revealed that the anastomotic structure of the tissue with hydrogel intervention was more intact than that of the control. Thus, the PAAm/Alg-Ca²⁺_0.5M hydrogel has been demonstrated to function effectively as a cooling agent, offering a new strategy for thermal damage control in RF tissue welding.