Innovative Surface Modification Techniques for Biodegradable Implants

A special issue of Coatings (ISSN 2079-6412). This special issue belongs to the section "Surface Characterization, Deposition and Modification".

Deadline for manuscript submissions: closed (30 March 2021) | Viewed by 5165

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Guest Editor
UniSA STEM, University of South Australia, Mawson Lakes, SA 5095, Australia
Interests: surface engineering; advanced manufacturing; modelling; biomanufacturing; surface integrity; corrosion; biomaterials
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Special Issue Information

Dear Colleagues,

We would like to invite you to submit your interesting work to this Special Issue on "Innovative Surface Modifications for Biodegradable Implants”. Over the years, as alternatives to permanent or temporary metal implants, biodegradable materials have attracted a great deal of interest from researchers around the world. Different biodegradable materials including metals (e.g., Mg alloys) and polymers (e.g., PLA) are being developed and studied with the aim of their potential application as orthopedic (e.g., bone plates, screws, pins) and cardiovascular (e.g., stents) implants. However, one major issue that still limits the efficacy of clinical application is their rapid degradation in human body fluid, which causes the loss of mechanical integrity before the complete bone healing. To address this, researchers have investigated different surface-modification approaches to slow the degradation (i.e., corrosion) rate while retaining adequate surface integrity. Approaches including protective passive coatings (e.g., Ca-P HA, LDH, PCL, PLLA) and  mechanical treatments (e.g., peening, burnishing, machining) have widely been studied to improve corrosion resistance and biological properties. This has led to the recent clinical trials of biodegradable implants in Australia, Germany, and Korea. Overwhelming research in this regard has also shown that many factors involved in the modification process, substrate materials, surface characteristics, and corrosion mechanisms influence the final outcomes. Despite the reasonable success achieved to date, the development of new and innovative surface treatments and deeper understanding of the process mechanics and the degradation mechanism are crucial to realize the full potential of biodegradable implants. The aim of this Special Issue is to present the latest experimental and theoretical developments in the field, through a combination of original research papers and review articles from leading research groups around the world.

In particular, the topics of interest include, but are not limited to:

  • Innovative coating materials;
  • Novel coating techniques;
  • Novel mechanical treatments;
  • Experimental, theoretical, and simulation analysis of the surface modification techniques;
  • Modelling and experimental characterization of degradation mechanisms;
  • Development of new biodegradable materials and assessment of their properties;
  • Hybrid surfacing strategies combining coating and mechanical treatment;
  • Application trials of biodegradable implants in vitro or in vivo.

Dr. Mohammad Uddin
Guest Editor

Manuscript Submission Information

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Keywords

  • biodegradable implants
  • surface engineering
  • coatings
  • mechanical treatment
  • corrosion
  • surface integrity
  • biocompatibility

Published Papers (2 papers)

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Research

13 pages, 3540 KiB  
Article
Nanomechanical Behavior, Adhesion and Corrosion Resistance of Hydroxyapatite Coatings for Orthopedic Implant Applications
by Kaouther Khlifi, Hafedh Dhiflaoui, Amir Ben Rhouma, Joël Faure, Hicham Benhayoune and Ahmed Ben Cheikh Laarbi
Coatings 2021, 11(4), 477; https://doi.org/10.3390/coatings11040477 - 19 Apr 2021
Cited by 10 | Viewed by 2102
Abstract
The aim of this work was to investigate the nanomechanical, adhesion and corrosion resistance of hydroxyapatite (HAP) coatings. The electrodeposition process was used to elaborate the HAP coatings on Ti6Al4V alloy. The effect of hydrogen peroxide concentration H2 [...] Read more.
The aim of this work was to investigate the nanomechanical, adhesion and corrosion resistance of hydroxyapatite (HAP) coatings. The electrodeposition process was used to elaborate the HAP coatings on Ti6Al4V alloy. The effect of hydrogen peroxide concentration H2O2 on the electrolyte and the heat treatment was studied. Surface morphology of HAP coatings was assessed, before and after heat treatment, by scanning electron microscopy associated with X-ray microanalysis (SEM-EDXS). Moreover, X-ray diffraction (XRD) was performed to identify the coatings’ phases and composition. Nanoindentation and scratch tests were performed for nanomechanical and adhesion behavior analysis. The corrosion resistance of the uncoated, the as-deposited, and the heat-treated coatings was investigated by electrochemical test. The obtained results revealed that, with 9% of H2O2 and after heat treatment, the HAP film exhibited a compact and homogeneous microstructure. The film also showed a crystal growth: stoichiometric hydroxyapatite (HAP) and β-tricalcium phosphate (β-TCP). After heat treatment, the nanomechanical properties (H, E) were increased from 117 ± 7 MPa and 24 ± 1 GPa to 171 ± 10 MPa and 38 ± 1.5 GPa respectively. Critical loads (LC1, LC2, and LC3) were increased from 0.78 ± 0.04, 1.6 ± 0.01, and 4 ± 0.23 N to 1.45 ± 0.08, 2.46 ± 0.14, and 4.35 ± 0.25 N (respectively). Furthermore, the adhesion strength increased from 8 to 13 MPa after heat treatment. The HAP heat-treated samples showed higher corrosion resistance (Rp = 65.85 kΩ/cm2; Icorr = 0.63 µA/cm2; Ecorr = −167 mV/ECS) compared to as-deposited and uncoated samples. Full article
(This article belongs to the Special Issue Innovative Surface Modification Techniques for Biodegradable Implants)
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11 pages, 5429 KiB  
Article
A Sinter Visualization Device for Observing the Relationship Between Fillers and Porosity of Precursor-Derived Ceramic Coatings
by Guangxin Wang, Jinqing Wang, Jie Wang, Zuohe Chi, Guangxue Zhang, Zhiyi Zhou, Zhi Feng and Yunhao Xiong
Coatings 2020, 10(6), 552; https://doi.org/10.3390/coatings10060552 - 09 Jun 2020
Cited by 3 | Viewed by 2380
Abstract
Adding fillers to polysilazane (PSZ)-derived ceramic coating is one of the main methods used to reduce PSZ porosity. In this study, we designed a sinter visualization device for understanding the effect of fillers on coating porosity and observed pore evolution within the coating [...] Read more.
Adding fillers to polysilazane (PSZ)-derived ceramic coating is one of the main methods used to reduce PSZ porosity. In this study, we designed a sinter visualization device for understanding the effect of fillers on coating porosity and observed pore evolution within the coating sintering process using different filler ratios. When there was no filler in the coating, gas evolution occurred at the initial sintering stage due to a PSZ pyrolysis reaction. In the final stage, numerous cracks appeared because of volume shrinkage. It was determined that such coatings cannot provide good protection. Although the cracks disappeared after adding glass powder, many bubbles appeared. After adding ZrO2, the bubbles in the coating significantly reduced. When the volume ratio of PSZ/glass powder/ZrO2 was 1:2:1, the coating porosity after sintering was the lowest. Based on our visualization experimental results, we concluded that the glass powder’s healing effect and the ZrO2 skeleton effect were the main reasons for the reduced coating porosity. In addition, the sinter visualization device can be used to observe the surface morphology of other similar coatings during the sintering processes. Full article
(This article belongs to the Special Issue Innovative Surface Modification Techniques for Biodegradable Implants)
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