A cotton-derived carbon coating by thermolysis method for enhanced mechanical and bio-compatibility of NiTi alloy

To elevate the performance of NiTi alloy in medical devices, carbon coating derived from natural cotton has been successfully deposited onto the alloy surface using a one-step thermolysis method. Natural cotton soaked in copper sulfate was utilized as carbon raw material, and the deposition process was carried out at low vacuum and temperature requirements. The mechanical and bio-compatibility of the coating performance of resulted carbon layer has been studied comprehensively. The uniformity and mechanical properties of the carbon film prepared at 390 °C, with a holding time of 1–2 h, indicate that it should retain the alloy's excellent mechanical properties and superelasticity. Furthermore, the carbon coating improves the corrosion resistance compared to the raw alloy material. Observations of the proliferation and morphology of adhered human umbilical vein endothelial cells confirm the non-toxic effect of the carbon film. Additionally, the application of the carbon film significantly reduces the contact angle and enhances the adsorption of albumin in blood, suggesting that employing carbon films as bio-active layers is a viable approach to enhance the performance of NiTi-based blood implants and components.