Biomedical nanostructured coating for minimally invasive surgery devices applications: characterization, cell cytotoxicity evaluation and an animal study in rat.

BACKGROUND: Thermal injury and tissue sticking, which influence wound remodeling, are major concerns in electrosurgery. In this study, the effect of lateral thermal injury caused by different electrosurgical electrodes on hepatic remodeling was investigated. METHODS: A monopolar electrosurgical unit equipped with untreated stainless steel (SS) and chromium nitride coated stainless steel (CrN-SS) electrodes was used to create lesions on the liver lobes of adult rats. Animals were sacrificed for evaluations at 0, 3, 7, and 28 days postoperatively. RESULTS: CrN-SS needles generated lower levels of sticking tissue, and the thermographs showed that recorded highest temperature in liver tissue from the CrN-SS needle group was significantly lower than in the SS needle group. The total injury area of livers treated with CrN-SS needles was significantly lower than livers treated with SS needles at each time point. Moreover, the CrN-SS needles caused a relatively smaller area of lateral thermal injury, a smaller area of fibrotic tissue, and a faster process of hepatic remodeling in rat liver than the SS needles. Immunofluorescence staining and Western blot analysis showed that rats treated with CrN-SS needles expressed lower levels of NF-κB and caspase-3 postoperatively. CONCLUSIONS: This study reveals that the plating of electrodes with a CrN film is an efficient method for improving the performance of electrosurgical units and should benefit wound remodeling. However, more tests must be performed to confirm these promising findings in human patients.

Antibacterial nanostructured composite films for biomedical applications: microstructural characteristics, biocompatibility, and antibacterial mechanisms.

Hydrogenated Cu-incorporated diamond-like carbon (a-C:H/Cu) films were prepared in the present study using a radio-frequency plasma magnetron sputtering system at various CH4/Ar gas ratios. The a-C:H/Cu films were characterized by scanning electron microscopy, atomic force microscopy, Raman spectroscopy, transmission electron microscopy, nano-indentation and a contact angle goniometer. The antibacterial properties and cell cytotoxicity of a-C:H/Cu films were evaluated as per JIS Z2801:2010 and ISO 10993-5 specifications, respectively. The analytical results revealed that the production of a-C:H/Cu films varied with the CH4/Ar ratio, and the phase transformation (amorphous-like → nano-polycrystalline structure) was induced by Cu doping/ion bombardment and radical reactions. Moreover, it was found that the microhardness of the a-C:H/Cu films decreased with increasing Ar fraction in the gas ratio. The a-C:H/Cu films exhibited a high hydrophobic surface feature. The film which contained 77.3 ± 4.4 at.% Cu did not influence cell adhesion and proliferation behaviors. Antibacterial tests also demonstrated that a-C:H/Cu films possessed excellent antibacterial properties. Therefore, a-C:H/Cu films could be developed as promising antibacterial coatings for biomedical applications.

Development of silver-containing austenite antibacterial stainless steels for biomedical applications part I: microstructure characteristics, mechanical properties and antibacterial mechanisms.

The as-quenched (AQ) microstructure of the Ag-containing alloys was found to be essentially a mixture of austenite (γ) and Ag phases. The Ag phase precipitates had a face-centered-cubic structure and lattice parameter a = 4.09 Å. When the alloy contained Ag ≥0.2 wt%, the mechanical properties were slightly enhanced because of the precipitate strengthening by the Ag phase precipitates. Moreover, the Ag-containing alloys exhibited ductile fracture after tensile testing. The results of an antibacterial test revealed that the Ag phase precipitates play a key role in the antibacterial mechanism of Ag-containing alloys: Ag(+) ions released from the Ag phase precipitates can kill bacteria. It is suggested that as AISI 316L alloy has an Ag content ≥0.2 wt%, it will have excellent antibacterial properties against both Staphylococcus aureus and Escherichia coli, with an antibacterial rate of nearly 100%.