Article

Surface Modification of Biomaterials: A Quest for Blood Compatibility

UCL Centre for Nanotechnology & Regenerative Medicine, University College London, Pond Street, London NW3 2QG, UK.
International Journal of Biomaterials 05/2012; 2012:707863. DOI: 10.1155/2012/707863
Source: PubMed

ABSTRACT Cardiovascular implants must resist thrombosis and intimal hyperplasia to maintain patency. These implants when in contact with blood face a challenge to oppose the natural coagulation process that becomes activated. Surface protein adsorption and their relevant 3D confirmation greatly determine the degree of blood compatibility. A great deal of research efforts are attributed towards realising such a surface, which comprise of a range of methods on surface modification. Surface modification methods can be broadly categorized as physicochemical modifications and biological modifications. These modifications aim to modulate platelet responses directly through modulation of thrombogenic proteins or by inducing antithrombogenic biomolecules that can be biofunctionalised onto surfaces or through inducing an active endothelium. Nanotechnology is recognising a great role in such surface modification of cardiovascular implants through biofunctionalisation of polymers and peptides in nanocomposites and through nanofabrication of polymers which will pave the way for finding a closer blood match through haemostasis when developing cardiovascular implants with a greater degree of patency.

Download full-text

Full-text

Available from: Brian G Cousins, Jul 02, 2015
0 Followers
 · 
299 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The usefulness of nanoscale topography in improving vascular response in vitro was previously established in our study on hydrothermally modified titanium surfaces. To propose this strategy of surface modification for clinical translation onto metallic stents, it is imperative that the surface be also hemocompatible - an essential attribute for any blood contacting device. The present in vitro study focuses on a detailed hemocompatibility evaluation of titania nanostructures created through an alkaline hydrothermal route on metallic Ti stent prototypes. Direct interactions of TiO2 nanocues of varied morphologies with whole blood were studied under static conditions as well as using an in vitro circulation model mimicking arterial flow, with respect to polished Ti control. Nanomodified stent surfaces upon contact with human blood showed negligible hemolysis under constant shear and static conditions. Coagulation profile testing indicated that surface roughness of nanomodified stents induced no alterations in the normal clotting times, with insignificant thrombus formation and minimal inflammatory reaction. Endothelialized nanomodified Ti surfaces were found to inhibit both activation as well as aggregation of platelets compared to the control surface, with the endothelium formed on the nanosurfaces having an increased expression of anti-thrombogenic genes. Such a nanotextured Ti surface which is anti-thrombogenic and promotes endothelialization would be a cost-effective option to drug eluting stents or polymer coated stents for overcoming in-stent restenosis.
    Acta biomaterialia 08/2013; DOI:10.1016/j.actbio.2013.08.023 · 5.68 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Cardiovascular implants find wide clinical applications, making a great contribution to the treatment of cardiovascular diseases. Such devices, endovascular stents, artificial vascular grafts, prosthetic heart valves to name a few typical examples, have been the mainstay of cardiovascular surgery. However, failure cases of the implants still exist, which urge us to understand what has happened at the blood-contacting interface and how the tissues have responded during the post-implantation period. Aiming to eliminate these pathological events, various approaches of surface modification of the cardiovascular devices have been used in order to improve hemocompatibility and cytocompatibility. In this review, the blood-biomaterial interfacial events and the evolution of the surface modification strategies are discussed, together with the recent developments on the surface modification of cardiovascular materials like biomimetic extracellular matrix and accelerated endothelialization. These novel surface modification strategies open a new chapter on designing ideal blood-friendly implantable materials. (C) 2013 Published by Elsevier B.V.
    Surface and Coatings Technology 10/2013; 233:80-90. DOI:10.1016/j.surfcoat.2013.02.008 · 2.20 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Cardiovascular disease is the dominant cause of mortality in developed countries, with coronary artery disease (CAD) a predominant contributor. The development of stents to treat CAD was a significant innovation, facilitating effective percutaneous coronary revascularization. Coronary stents have evolved from bare metal compositions, to incorporate advances in pharmacological therapy in what are now known as drug eluting stents (DES). Deployment of a stent overcomes some limitations of balloon angioplasty alone, but provides an acute stimulus for thrombus formation and promotes neointimal hyperplasia. First generation DES effectively reduced in-stent restenosis, but profoundly delay healing and are susceptible to late stent thrombosis, leading to significant clinical complications in the long term. This review characterizes the development of coronary stents, detailing the incremental improvements, which aim to attenuate the major clinical complications of thrombosis and restenosis. Despite these enhancements, coronary stents remain fundamentally incompatible with the vasculature, an issue which has largely gone unaddressed. We highlight the latest modifications and research directions that promise to more holistically design coronary implants that are truly biocompatible.
    Materials 12/2013; 7(2). DOI:10.3390/ma7020769 · 1.88 Impact Factor