Abstract: BACKGROUND: The increasing prevalence of minimally invasive surgery has placed higher demands on high-frequency electrosurgical equipment. Imported minimally invasive tungsten alloy electrodes offer high cutting precision, low tissue adhesion, and good biocompatibility, but their high cost limits their widespread application. Therefore, conducting biocompatibility and preclinical animal studies on Chinese-made 3D-printed minimally invasive tungsten alloy needle electrodes can provide a scientific basis for the research and development of Chinese-made minimally invasive electrodes. 
OBJECTIVE: To evaluate the biocompatibility and preclinical safety of Chinese-made 3D-printed tungsten alloy needle-shaped electrodes. 
METHODS: (1) Biocompatibility: L-929 cells were co-cultured with extracts from Chinese-made 3D-printed minimally invasive tungsten alloy needle electrodes at different concentrations (100%, 50%, 25%, and 12.5%), and the cytotoxicity of the materials was assessed using the MTT assay. Intradermal stimulation experiments were performed on New Zealand white rabbits to evaluate the skin irritation of the Chinese-made 3D-printed minimally invasive tungsten alloy needle electrodes. Sensitization experiments were performed on albino guinea pigs to evaluate the skin allergic reaction of the Chinese-made 3D-printed minimally invasive tungsten alloy needle electrodes. (2) Preclinical animal experiments: Thirty-six SD rats were randomly divided into a 304 stainless steel electrode group (n=12), an imported minimally invasive tungsten alloy needle electrode group (n=12), and a Chinese-made 3D-printed minimally invasive tungsten alloy needle electrode group (n=12). The corresponding electrodes were used to incise the abdominal subcutaneous tissue and abdominal wall muscle layer. The incisions were sutured, and the amount of adhesion on the electrode surface, intraoperative blood loss, and smoke formation were recorded. Fourteen days after surgery, wound healing, fat liquefaction, and incision histological morphology were observed. 
RESULTS AND CONCLUSION: (1) MTT assays showed that the cell survival rate in the extracts from the Chinese-made 3D-printed minimally invasive tungsten alloy needle electrode groups was above 80%, with no significant cytotoxicity. Intradermal stimulation and sensitization experiments showed that the Chinese-made 3D-printed minimally invasive tungsten alloy needle electrodes did not cause significant skin irritation or allergic reactions. (2) Compared with the 304 stainless steel electrode group, the Chinese-made 3D-printed minimally invasive tungsten alloy needle electrode group showed reduced surface adhesion mass and increased intraoperative bleeding and smoke formation (P < 0.05). There were no significant differences in surface adhesion mass, intraoperative bleeding, or smoke formation between the Chinese-made and imported 3D-printed minimally invasive tungsten alloy needle electrode groups (P > 0.05). There were no significant differences in wound healing, fat liquefaction, or adverse wound reactions among the three groups (P > 0.05). Hematoxylin-eosin staining revealed mild inflammatory cell infiltration in the incision tissues of all three groups, consistent with the normal pathological process of wound repair. No abnormal immune response or delayed healing was observed. (3) These results demonstrate that the Chinese-made 3D-printed minimally invasive tungsten alloy needle electrodes exhibit excellent biocompatibility and safety, and their overall performance is comparable to that of imported tungsten needle electrodes.

Key words: 3D printing, tungsten alloy, needle-shaped electrode, biocompatibility, cytotoxicity, intradermal irritation, animal experiment, preclinical study