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Polymer Matrix Nanocomposites: Recent Advancements and Applications
Published in Kaushik Pal, Hybrid Nanocomposites, 2019
The design of cardiovascular interfaces necessitates a combination of amphiphilicity and antithrombogenicity. Amphiphilicity ensures optimal endothelial cell response at the vascular interface. Thrombogenicity refers to blood clot formation and can lead to early graft occlusion. Using reports of polyhedral oligomeric silsequioxanes (POSS) acting as an amphiphile at the water–air interface, researchers have studied the possibility of using POSS at the vascular interface. The strong intermolecular forces between constituent molecules and neighbors and the robust framework of shorter bond lengths make POSS nanocomposites more resistant to degradation. Initial work has shown that POSS nanocomposites are cytocompatible, making them potentially suitable for tissue engineering [123, 124]. Future efforts in this field are directed at assessing the thrombogenic potential of these nanocomposites, which would be critical in their application as cardiovascular interfaces [123, 124].
Plasma Electrolytic Oxidation
Published in Hatem M.A. Amin, Ahmed Galal, Corrosion Protection of Metals and Alloys Using Graphene and Biopolymer Based Nanocomposites, 2021
Aleksandra A. Gladkova, Dmitriy G. Tagabilev, Miki Hiroyuki
Aside from an improvement of the surface properties of orthopedic and dental implants, PEO could be useful for surface modification of endovascular devises such as valve prostheses, vascular stents, etc. Ultrafine-grained pure Ti prepared by equal-channel angular pressing has favorable mechanical performance and does not contain alloy elements that are toxic to the human body. Thus, it has a potential clinical value in applications such as cardiac valve prostheses, and vascular stents. To overcome the material’s inherent thrombogenicity, surface-coating modification is a crucial pathway to enhance blood compatibility. The PEO method can significantly enhance the blood compatibility of ultrafine-grained pure Ti, increasing its potential for practical applications in cardiovascular surgery. An electrolyte solution of sodium silicate + sodium polyphosphate + calcium acetate and the PEO technique were employed by Xu et al. [95] for in situ oxidation of an ultrafine-grained pure Ti surface. A porous coating with anatase- and rutile-phase TiO2 was generated, and wettability and blood compatibility were examined. The results showed that, in comparison with ultrafine-grained pure Ti substrate, the PEO coating had a rougher surface, smaller contact angles for distilled water, and higher surface energy. PEO modification effectively reduced the hemolysis rate, extended the dynamic coagulation time, prothrombin time (PT), and activated partial thromboplastin time (APTT), reduced the amount of platelet adhesion and the degree of deformation, and enhanced blood compatibility. In particular, the sample with an oxidation time of nine minutes possessed the highest surface energy, largest PT and APTT values, smallest hemolysis rate, less platelet adhesion, a lesser degree of deformation, and a more favorable blood compatibility.
In Vitro models for thrombogenicity testing of blood-recirculating medical devices
Published in Expert Review of Medical Devices, 2019
The development of blood-recirculating medical devices, such as extracorporeal membrane oxygenators (ECMO), mechanical circulatory support (MCS), and hemodialyzers includes an evaluation of the biocompatibility of the materials and corresponding device design. Because thromboembolism remains a potential complication from the use of these devices [1], thrombogenicity testing in both in vitro and in vivo settings is an integral part of designing them for therapeutic use. Guidelines for in vitro thrombogenicity tests that are described in standards documents, such as ISO 10993–4 [2], vary depending on the type of blood-recirculating device being assessed. These tests provide a preliminary characterization of a device or material’s thrombosis potential when exposed to blood and are usually followed with in vivo testing. In general, blood-recirculating devices are exposed to large blood volumes at physiological flow rates for an extended period of time. While the clinical applications for devices differ, they all require devices to remain patent over the blood exposure period. Currently, these devices can be used as a bridge to transplantation or bridge to recovery therapies. As MCS, ECMO, and hemodialysis technology improve, the next generation of devices are targeted for use as wearable or implantable artificial organs to provide long-term resolution to heart, lung and kidney failure, respectively. To meet this need, improved in vitro thrombosis testing methods are required to efficiently and accurately assess novel implantable devices.
Surface engineering in artificial heart valves
Published in Surface Engineering, 2023
Lakshmi Gopal, Tirumalai Sudarshan
While progressive designs of prosthetic heart valves have improved haemodynamic properties, the introduction of a foreign object into the human body comes with its own set of complications [5]. The common problems include thrombosis, haemorrhage related to anticoagulant use, infections, valve failure, tissue hyperplasia, and overgrowth. Thrombogenicity or clot formation on the surfaces of the internal prosthesis is triggered by the adhesion and activation of platelets on them. This in turn is guided by the protein layer, especially human plasma fibrinogen (HPF). Inflammatory reactions such as restenosis and calcification are also caused by the release of toxic ions from the metals or alloys and the degradation of polymeric components of the artificial valves.
Heparinized PCL/keratin mats for vascular tissue engineering scaffold with potential of catalytic nitric oxide generation
Published in Journal of Biomaterials Science, Polymer Edition, 2018
Xiuzhen Wan, Yanfang Wang, Xingxing Jin, Pengfei Li, Jiang Yuan, Jian Shen
Antithrombogenicity is a priority for blood-contact materials such as vascular tissue engineering scaffold. Platelet adhesion test is usually used to evaluate the thrombogenicity of specimen. Figure 5a demonstrates that platelets adhered to the heparinized PCL mats were lower than that adhered to pure PCL and PCL/keratin mats. Also, the cells displayed a round shape, indicating minor activation and good hemocompatibility.