Special Issue "Advances in Medical Device Coatings"

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A special issue of Coatings (ISSN 2079-6412).

Deadline for manuscript submissions: closed (20 September 2013)

Special Issue Editor

Guest Editor
Dr. Denis Dowling (Website)

Surface Engineering Research Group, Room 223, UCD Engineering and Materials Science Centre, University College Dublin, Belfield, Dublin 4, Ireland
Fax: +353 (0)1 283 0534
Interests: coatings; atmospheric plasmas; cell adhesion; medical devices; tailored surface chemistry

Special Issue Information

Dear Colleagues,

There has been an enormous growth in the application of coatings onto medical devices in the last few years. Examples of these coatings range from hydroxyapetite, which enhance cell attachment onto orthopaedic implants, to antimicrobial silver coatings on catheters, drug eluting coatings on stents and blood compatible coatings such as heparin.  These coatings are deposited using processes such as plasma spraying, dipping and spin coating.  More recently novel coating techniques such as laser treatments, low temperature atmospheric plasmas and microblasting techniques have also been developed for the deposition of bioactive coatings.  The objective of this review is to highlight new developments in the deposition and characterisation of coatings for both implantable and non-implantable medical device applications. Issues such as how the presence of specific chemical functionalities or coating morphology influences protein and / or cell adhesion or anti-microbial activity will be considered. Developing methods of assessing the potential longer term stability (ageing) issues associated with coated devices are critically important prior to the clinical application of these devices.  Included also in this review are both in-vitro and in-vivo studies on the performance of both novel coatings and / or processing technologies.

Dr. Denis Dowling
Guest Editor

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Coatings is an international peer-reviewed Open Access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 300 CHF (Swiss Francs). English correction and/or formatting fees of 250 CHF (Swiss Francs) will be charged in certain cases for those articles accepted for publication that require extensive additional formatting and/or English corrections.

Keywords

  • coatings
  • thin film
  • biocompatibility
  • chemical functionality
  • cell attachment
  • surface treatment

Published Papers (7 papers)

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Research

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Open AccessArticle Gas Permeation, Mechanical Behavior and Cytocompatibility of Ultrathin Pure and Doped Diamond-Like Carbon and Silicon Oxide Films
Coatings 2013, 3(4), 268-300; doi:10.3390/coatings3040268
Received: 17 September 2013 / Revised: 20 November 2013 / Accepted: 6 December 2013 / Published: 16 December 2013
Cited by 3 | PDF Full-text (2096 KB) | HTML Full-text | XML Full-text
Abstract
Protective ultra-thin barrier films gather increasing economic interest for controlling permeation and diffusion from the biological surrounding in implanted sensor and electronic devices in future medicine. Thus, the aim of this work was a benchmarking of the mechanical oxygen permeation barrier, cytocompatibility, [...] Read more.
Protective ultra-thin barrier films gather increasing economic interest for controlling permeation and diffusion from the biological surrounding in implanted sensor and electronic devices in future medicine. Thus, the aim of this work was a benchmarking of the mechanical oxygen permeation barrier, cytocompatibility, and microbiological properties of inorganic ~25 nm thin films, deposited by vacuum deposition techniques on 50 µm thin polyetheretherketone (PEEK) foils. Plasma-activated chemical vapor deposition (direct deposition from an ion source) was applied to deposit pure and nitrogen doped diamond-like carbon films, while physical vapor deposition (magnetron sputtering in pulsed DC mode) was used for the formation of silicon as well as titanium doped diamond-like carbon films. Silicon oxide films were deposited by radio frequency magnetron sputtering. The results indicate a strong influence of nanoporosity on the oxygen transmission rate for all coating types, while the low content of microporosity (particulates, etc.) is shown to be of lesser importance. Due to the low thickness of the foil substrates, being easily bent, the toughness as a measure of tendency to film fracture together with the elasticity index of the thin films influence the oxygen barrier. All investigated coatings are non-pyrogenic, cause no cytotoxic effects and do not influence bacterial growth. Full article
(This article belongs to the Special Issue Advances in Medical Device Coatings)
Open AccessArticle Development and in Vitro Characterization of Photochemically Crosslinked Polyvinylpyrrolidone Coatings for Drug-Coated Balloons
Coatings 2013, 3(4), 253-267; doi:10.3390/coatings3040253
Received: 20 September 2013 / Revised: 7 November 2013 / Accepted: 27 November 2013 / Published: 5 December 2013
Cited by 4 | PDF Full-text (764 KB) | HTML Full-text | XML Full-text
Abstract
Polyvinylpyrrolidone (PVP) is a conventionally applied hydrophilic lubricious coating on catheter-based cardiovascular devices, used in order to ease movement through the vasculature. Its use as drug reservoir and transfer agent on drug-coated balloons (DCB) is therefore extremely promising with regard to the [...] Read more.
Polyvinylpyrrolidone (PVP) is a conventionally applied hydrophilic lubricious coating on catheter-based cardiovascular devices, used in order to ease movement through the vasculature. Its use as drug reservoir and transfer agent on drug-coated balloons (DCB) is therefore extremely promising with regard to the simplification of its approval as a medical device. Here, we developed a PVP-based coating for DCB, containing paclitaxel (PTX) as a model drug, and studied the impact of crosslinking via UV radiation on drug stability, wash off, and transfer during simulated use in an in vitro vessel model. We showed that crosslinking was essential for coating stability and needed to be performed prior to PTX incorporation due to decreased drug bioavailability as a result of photodecomposition and/or involvement in vinylic polymerization with PVP under UV radiation. Moreover, the crosslinking time needed to be carefully controlled. While short radiation times did not provide enough coating stability, associated with high wash off rates during DCB insertion, long radiation times lowered drug transfer efficiency upon balloon expansion. A ten minutes radiation of PVP, however, combined a minimized drug wash off rate of 34% with an efficient drug transfer of 49%, underlining the high potential of photochemically crosslinked PVP as a coating matrix for DCB. Full article
(This article belongs to the Special Issue Advances in Medical Device Coatings)
Open AccessArticle Polyurethane Organosilicate Nanocomposites as Blood Compatible Coatings
Coatings 2012, 2(1), 45-63; doi:10.3390/coatings2010045
Received: 16 December 2011 / Revised: 20 February 2012 / Accepted: 22 February 2012 / Published: 27 February 2012
Cited by 2 | PDF Full-text (1639 KB) | HTML Full-text | XML Full-text
Abstract
Polymer clay nanocomposites (NCs) show remarkable potential in the field of drug delivery due to their enhanced barrier properties. It is hypothesised that well dispersed clay particles within the polymer matrix create a tortuous pathway for diffusing therapeutic molecules, thereby resulting in [...] Read more.
Polymer clay nanocomposites (NCs) show remarkable potential in the field of drug delivery due to their enhanced barrier properties. It is hypothesised that well dispersed clay particles within the polymer matrix create a tortuous pathway for diffusing therapeutic molecules, thereby resulting in more sustained release of the drug. As coatings for medical devices, these materials can simultaneously modulate drug release and improve the mechanical performance of an existing polymer system without introducing additional materials with new chemistries that can lead to regulatory concerns. In this study, polyurethane organosilicate nanocomposites (PUNCs) coated onto stainless steel wires were evaluated for their feasibility as blood compatible coatings and as drug delivery systems. Heparin was selected as the model drug to examine the impact of silicate loading and modifier chain length in modulating release. Findings revealed that better dispersion was achieved from samples with lower clay loadings and longer alkyl chains. The blood compatibility of PUNCs as assessed by thrombin generation assays showed that the addition of silicate particles did not significantly decrease the thrombin generation lag time (TGT, p = 0.659) or the peak thrombin (p = 0.999) of polyurethane (PU). PUNC coatings fabricated in this research were not cytotoxic as examined by the cell growth inhibition assay and were uniformly intact, but had slightly higher growth inhibition compared to PU possibly due to the presence of organic modifiers (OM). The addition of heparin into PUNCs prolonged the TGT, indicating that heparin was still active after the coating process. Cumulative heparin release profiles showed that the majority of heparin released was from loosely attached residues on the surface of coils. The addition of heparin further prolonged the TGT as compared to coatings without added heparin, but a slight decrease in heparin activity was observed in the NCs. This was thought to be from competitive interactions between clay-heparin that influenced the formation of the ternary complex between heparin, ATIII thrombin. In summary, the feasibility of using PUNC as drug delivery coatings was shown by the good uniformity in the coating, absence of by-products from the coating process, and the release of active molecules without significantly interfering with their activity. Full article
(This article belongs to the Special Issue Advances in Medical Device Coatings)
Open AccessArticle Biocompatibility of Niobium Coatings
Coatings 2011, 1(1), 72-87; doi:10.3390/coatings1010072
Received: 2 August 2011 / Revised: 1 September 2011 / Accepted: 15 September 2011 / Published: 22 September 2011
Cited by 20 | PDF Full-text (1391 KB) | HTML Full-text | XML Full-text
Abstract
Niobium coatings deposited by magnetron sputtering were evaluated as a possible surface modification for stainless steel (SS) substrates in biomedical implants. The Nb coatings were deposited on 15 mm diameter stainless steel substrates having an average surface roughness of 2 mm. To [...] Read more.
Niobium coatings deposited by magnetron sputtering were evaluated as a possible surface modification for stainless steel (SS) substrates in biomedical implants. The Nb coatings were deposited on 15 mm diameter stainless steel substrates having an average surface roughness of 2 mm. To evaluate the biocompatibility of the coatings three different in vitro tests, using human alveolar bone derived cells, were performed: cellular adhesion, proliferation and viability. Stainless steel substrates and tissue culture plastic were also studied, in order to give comparative information. No toxic response was observed for any of the surfaces, indicating that the Nb coatings act as a biocompatible, bioinert material. Cell morphology was also studied by immune-fluorescence and the results confirmed the healthy state of the cells on the Nb surface. X-ray diffraction analysis of the coating shows that the film is polycrystalline with a body centered cubic structure. The surface composition and corrosion resistance of both the substrate and the Nb coating were also studied by X-ray photoelectron spectroscopy and potentiodynamic tests. Water contact angle measurements showed that the Nb surface is more hydrophobic than the SS substrate. Full article
(This article belongs to the Special Issue Advances in Medical Device Coatings)
Open AccessArticle A Modified Surface on Titanium Deposited by a Blasting Process
Coatings 2011, 1(1), 53-71; doi:10.3390/coatings1010053
Received: 16 July 2011 / Revised: 23 August 2011 / Accepted: 1 September 2011 / Published: 13 September 2011
Cited by 7 | PDF Full-text (1194 KB) | HTML Full-text | XML Full-text
Abstract
Hydroxyapatite (HA) coating of hard tissue implants is widely employed for its biocompatible and osteoconductive properties as well as its improved mechanical properties. Plasma technology is the principal deposition process for coating HA on bioactive metals for this application. However, thermal decomposition [...] Read more.
Hydroxyapatite (HA) coating of hard tissue implants is widely employed for its biocompatible and osteoconductive properties as well as its improved mechanical properties. Plasma technology is the principal deposition process for coating HA on bioactive metals for this application. However, thermal decomposition of HA can occur during the plasma deposition process, resulting in coating variability in terms of purity, uniformity and crystallinity, which can lead to implant failure caused by aseptic loosening. In this study, CoBlastTM, a novel blasting process has been used to successfully modify a titanium (V) substrate with a HA treatment using a dopant/abrasive regime. The impact of a series of apatitic abrasives under the trade name MCD, was investigated to determine the effect of abrasive particle size on the surface properties of both microblast (abrasive only) and CoBlast (HA/abrasive) treatments. The resultant HA treated substrates were compared to substrates treated with abrasive only (microblasted) and an untreated Ti. The HA powder, apatitic abrasives and the treated substrates were characterized for chemical composition, coating coverage, crystallinity and topography including surface roughness. The results show that the surface roughness of the HA blasted modification was affected by the particle size of the apatitic abrasives used. The CoBlast process did not alter the chemistry of the crystalline HA during deposition. Cell proliferation on the HA surface was also assessed, which demonstrated enhanced osteo-viability compared to the microblast and blank Ti. This study demonstrates the ability of the CoBlast process to deposit HA coatings with a range of surface properties onto Ti substrates. The ability of the CoBlast technology to offer diversity in modifying surface topography offers exciting new prospects in tailoring the properties of medical devices for applications ranging from dental to orthopedic settings. Full article
(This article belongs to the Special Issue Advances in Medical Device Coatings)

Review

Jump to: Research

Open AccessReview Biomedical Nanoparticles: Overview of Their Surface Immune-Compatibility
Coatings 2014, 4(1), 139-159; doi:10.3390/coatings4010139
Received: 11 October 2013 / Revised: 8 January 2014 / Accepted: 30 January 2014 / Published: 12 February 2014
Cited by 14 | PDF Full-text (270 KB) | HTML Full-text | XML Full-text
Abstract
Diagnostic- and therapeutic release-aimed nanoparticles require the highest degree of biocompatibility. Some physical and chemical characteristics of such nanomaterials are often at odds with this requirement. For instance, metals with specific features used as contrast agents in magnetic resonance imaging need particular [...] Read more.
Diagnostic- and therapeutic release-aimed nanoparticles require the highest degree of biocompatibility. Some physical and chemical characteristics of such nanomaterials are often at odds with this requirement. For instance, metals with specific features used as contrast agents in magnetic resonance imaging need particular coatings to improve their blood solubility and increase their biocompatibility. Other examples come from the development of nanocarriers exploiting the different characteristics of two or more materials, i.e., the ability to encapsulate a certain drug by one core-material and the targeting capability of a different coating surface. Furthermore, all these “human-non-self” modifications necessitate proofs of compatibility with the immune system to avoid inflammatory reactions and resultant adverse effects for the patient. In the present review we discuss the molecular interactions and responses of the immune system to the principal nanoparticle surface modifications used in nanomedicine. Full article
(This article belongs to the Special Issue Advances in Medical Device Coatings)
Open AccessReview Nano and Microscale Topographies for the Prevention of Bacterial Surface Fouling
Coatings 2014, 4(1), 37-59; doi:10.3390/coatings4010037
Received: 23 November 2013 / Revised: 20 December 2013 / Accepted: 8 January 2014 / Published: 17 January 2014
Cited by 18 | PDF Full-text (949 KB) | HTML Full-text | XML Full-text
Abstract
Bacterial surface fouling is problematic for a wide range of applications and industries, including, but not limited to medical devices (implants, replacement joints, stents, pacemakers), municipal infrastructure (pipes, wastewater treatment), food production (food processing surfaces, processing equipment), and transportation (ship hulls, aircraft [...] Read more.
Bacterial surface fouling is problematic for a wide range of applications and industries, including, but not limited to medical devices (implants, replacement joints, stents, pacemakers), municipal infrastructure (pipes, wastewater treatment), food production (food processing surfaces, processing equipment), and transportation (ship hulls, aircraft fuel tanks). One method to combat bacterial biofouling is to modify the topographical structure of the surface in question, thereby limiting the ability of individual cells to attach to the surface, colonize, and form biofilms. Multiple research groups have demonstrated that micro and nanoscale topographies significantly reduce bacterial biofouling, for both individual cells and bacterial biofilms. Antifouling strategies that utilize engineered topographical surface features with well-defined dimensions and shapes have demonstrated a greater degree of controllable inhibition over initial cell attachment, in comparison to undefined, texturized, or porous surfaces. This review article will explore the various approaches and techniques used by researches, including work from our own group, and the underlying physical properties of these highly structured, engineered micro/nanoscale topographies that significantly impact bacterial surface attachment. Full article
(This article belongs to the Special Issue Advances in Medical Device Coatings)
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