Novel DLC Coating Technique on an Inner-wall of Extended Polytetrafluoroethylene Vascular Grafts Using Methane Plasma Produced by AC HV Discharge

Abstract

Expanded-polytetrafluoroethylene (ePTFE) generally exhibits good compatibility with blood in the form of a vascular graft material; however, the small diameter grafts exhibit a low patency rate. ePTFE, with a diameter of less than 6 mm, is usually not used to perform a bypass surgery because of its high occlusion rate due to thrombosis or thick neointimal formation. Therefore, to improve the patency rate of ePTFE, coating the inner surface of ePTFE using Diamond-like Carbon (DLC), which exhibits outstanding biocompatibility, is investigated. However, in reality, medical applications for a long-sized tube that has a diameter of less than 6 mm with a DLC-coated inner wall are scarce. Hence, in this study, AC high-voltage methane plasma Chemical Vapor Deposition is employed to form the bio-compatibilized inner wall of a small-diameter long-sized medical tube, and a Hydrogenated Amorphous Carbon (a-C:H) deposition technique is developed. Further, methane plasma discharge is confirmed to be confined within the ePTFE vascular graft tube (inner diameter of 4 mm and an overall length of 150 mm) with the inner wall being successfully coated by the a-C:H film.

Comprehensive hemocompatibility analysis on the application of Diamond-like carbon to ePTFE artificial vascular prosthesis

“…The deposition conditions for ePTFE sheets were as follows: ultimate vacuum pressure, 7.0 × 10 −3 Pa; process pressure, 5 Pa; CH 4 gas introduced at 10 sccm using a mass ow controller; RF output power, 70 W; and processing time, 5 minutes. Details for the ePTFE graft deposition system have been reported previously 12 . Coating with DLC was con rmed using Ramen spectroscopy.…”

Intraluminal diamond‐like carbon coating with anti‐adhesion and anti‐biofilm effects for uropathogens: A novel technology applicable to urinary catheters

“…The coating process was then performed in the chamber using the AC high-voltage methane plasma-enhanced CVD method. 12 The physicochemical properties of the DLC-coated/ uncoated silicon surface were evaluated by 3D non-contact surface scanning using a New View 5320 (Zygo Corporation, Middlefield, OH, USA) and by scanning electron microscopy using a HITACHI S-4800 (Hitachi High-Tech Corporation, Tokyo, Japan). The surface morphology of DLC-coated/ uncoated silicon was visualized with the SEM before and after the bacterial experiments.…”

“…11 Despite these promising reports, DLC coatings have not been applied for use in urinary catheters, owing to technical limitations associated with application of DLC coatings into the lumen of small-diameter tubes; DLC coatings were only previously demonstrated on flat surfaces using conventional methods. In 2018, however, Nakatani et al 12 developed the world's first technique for DLC coating on the inner surface of a thin tube. As bacterial biofilms are known to develop more in the lumen than on the outer surface of tubular medical devices, 13 coatings exhibiting anti-adhesion and anti-biofilm effects should be applied to the lumen.…”

“…In 2018, however, Nakatani et al . 12 developed the world’s first technique for DLC coating on the inner surface of a thin tube. As bacterial biofilms are known to develop more in the lumen than on the outer surface of tubular medical devices, 13 coatings exhibiting anti‐adhesion and anti‐biofilm effects should be applied to the lumen.…”

Rapid Functionalization of Polytetrafluorethylene (PTFE) Surfaces with Nitrogen Functional Groups

“…Nakatani et al [22] used a low-frequency RF discharge to sustain the plasma in methane at the pressure of 40 Pa. The vascular grafts made from PTFE were placed into the plasma reactor and homogeneous plasma was sustained inside the grafts.…”