Surface engineering of artificial heart valve disks using nanostructured thin films deposited by chemical vapour deposition and sol-gel methods

Abstract

Pyrolytic carbon (PyC) is widely used in manufacturing commercial artificial heart valve disks (HVD). Although PyC is commonly used in HVD, it is not the best material for this application since its blood compatibility is not ideal for prolonged clinical use. As a result thrombosis often occurs and the patients are required to take anti-coagulation drugs on a regular basis in order to minimize the formation of thrombosis. However, anti-coagulation therapy gives rise to some detrimental side effects in patients. Therefore, it is extremely urgent that newer and more technically advanced materials with better surface and bulk properties are developed. In this paper, we report the mechanical properties of PyC-HVD, i.e. strength, wear resistance and coefficient of friction. The strength of the material was assessed using Brinell indentation tests. Furthermore, wear resistance and coefficient of friction values were obtained from pin-on-disk testing. The micro-structural properties of PyC were characterized using XRD, Raman spectroscopy and SEM analysis. Also in this paper we report the preparation of freestanding nanocrystalline diamond films (FSND) using the time-modulated chemical vapour deposition (TMCVD) process. Furthermore, the sol-gel technique was used to uniformly coat PyC-HVD with dense, nanocrystalline-titanium oxide (nc-TiO2) coatings. The as-grown nc-TiO2 coatings were characterized for microstructure using SEM and XRD analysis.

Tantalum Nitride-Decorated Titanium with Enhanced Resistance to Microbiologically Induced Corrosion and Mechanical Property for Dental Application

“…Recent studies show that Ta-based coatings including TaN and tantalum oxide (TaO) coating exert antibacterial effect against Staphylococcus aureus and Actinobacillus actinomycetemcomitans [ 31 , 32 ]. Despite the excellent biocompatibility/cytocompatibility of TaN has allowed its use in artificial heart valves [ 33 ], dental implant [ 32 ] and other numerous biomedical coatings [ 30 , 32 ], e.g. a Ag-doped TaN film with suppressed bacterial activity was developed by Huang et al on Ti-based dental implants [ 32 ], the impact of bio-corrosion resulting from bacteria on the pristine TaN-decorated implant abutment in the oral cavity, to our knowledge, has not been reported and investigated.…”

Nanocomposite and Nanostructured Carbon-based Films as Growth Substrates for Bone Cells

“…However, in experiments in vivo, pyrolytic carbon and pyrolytic graphite/silicon-carbide, implanted into rabbit mandibles, induced fibrous capsule formation and infiltration with multinucleated phagocytic cells (Maropis et al, 1977). On the other hand, similarly as the amorphous hydrogenated carbon, pyrolytic carbon (particularly in the form of so-called Low Temperature Isotropic pyrolytic carbon, LTI) has been used as a coating for commercially available blood contacting devices, such as artificial heart valves (Kwok et al, 2004;Jackson et al, 2006), in order to prevent hemocoagulation and thrombus formation on these devices, although its hemocompatibility was not ideal. LTI has been also used in orthopedic applications, namely for construction of joint replacements, because it has been reported to reduce the cartilage wear (Bernasek et al, 2009).…”

Pivoting system fracture in a bileaflet mechanical valve: A case report

“…And despite the considerable improvements in the manufacture and quality control procedures for such devices, the potential risk for failure still exists 42. The introduction of new devices requires an in depth analysis of both the material characteristics and device performance,77–79 and any innovation in either material or design must be carefully validated 80, 81. Any new commercial product must be equivalent to or better than its existing competitors.…”