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Special Issue "Synthetic and Biological-Derived Hydroxyapatite Implant Coatings"

A special issue of Coatings (ISSN 2079-6412). This special issue belongs to the section "Bioactive Coatings and Biointerfaces".

Deadline for manuscript submissions: 30 November 2021.

Special Issue Editors

Dr. Liviu Duta
E-Mail Website
Guest Editor
Lasers Department, National Institute for Lasers, Plasma and Radiation Physics, 077125 Magurele, Romania
Interests: thin film and nanoparticles synthesis; biocompatible and bioactive materials for medical applications; pulsed laser technologies
Special Issues and Collections in MDPI journals
Prof. Dr. Faik Nuzhet Oktar
E-Mail Website
Guest Editor
Marmara University, Faculty of Engineering, Bioengineering Department, Istanbul, Turkey; Nanotechnology and Biomaterial Research and Implementation Centre, Istanbul, Turkey
Interests: Pulsed laser deposition (PLD); Plasma coating; Production methods of nano-biomaterials and application areas in health sector; Drug release systems; In vitro and in vivo studies; Biomimetic production methods and applications; Electro-Spinning technique and related applications; Production methods and development of bioceramics; Production of smart nano-biopolymers to be used as carrier systems

Special Issue Information

Dear Colleagues,

We warmly invite you to submit your recent work in the field of synthesis and characterization techniques of hydroxyapatite (HA) coatings to the Special Issue “Synthetic and Biological-derived Hydroxyapatite Implant Coatings”.

In the last few decades, the field of bioactive materials for bone tissue engineering has emerged as one of the prominent approaches to tackling bone traumas and ailments, with an emphasis on the production of durable implants and bone substitutes capable of bypassing rejection complications.

HA is a well-known bioceramic which possesses a close chemical and structural resemblance to the mineral composition of bones and teeth of vertebrates. Despite their favorable bone regeneration properties, HA ceramics are very brittle, and this restricts their usage in high load-bearing applications. To overcome this drawback, HA can be applied as a coating on either metallic or polymeric implants, aiming to significantly improve the implant’s overall performance by harmoniously combining the excellent bioactivity of the ceramic with the mechanical advantages of the substrate implants.

Synthetic HA is commonly produced by several chemical routes, but recent methods to either extract or derive HA from natural sustainable resources (e.g., bones, sea-shells, various mineralogical resources) were reported. Biological-derived apatite is a carbonated HA, which contains various amounts of oligoelements and has a reduced crystallinity. Therefore, it differs from synthetic HA in terms of composition, stoichiometry, crystallinity degree, crystal size/morphology, and thus, degradation rate and overall biological performance.

Moreover, commercial thick plasma-sprayed HA coatings are susceptible to cracking and delamination and, owing to the high processing temperatures, could contain residual decomposition phases. In this respect, current research interests are rapidly advancing on two focused directions: (i) Increasing the biomimicry of HA coatings with respect to the composition and structure of bone apatite, and (ii) improving the present or even discovering alternative deposition techniques to allow for the fabrication of novel (doped) HA coatings with increased mechanical and biological performance.

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

  • Synthetic and biological-derived HA coatings for orthopedic and dental implants;
  • Drug delivery;
  • Composite HA-based coatings;
  • Doping of synthetic and biological-derived HA coatings;
  • Alternative methods for the deposition of synthetic and biological-derived HA coatings;
  • Biofunctional assessment of synthetic and biological-derived HA coatings.

Dr. Liviu Duta
Prof. Dr. Faik Nuzhet Oktar
Guest Editors

Manuscript Submission Information

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. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short 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 thoroughly refereed through a single-blind 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 monthly 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 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Synthetic and biological-derived hydroxyapatite coatings
  • Adherence
  • Osseointegration
  • Biocompatibility
  • Medical applications

Published Papers (7 papers)

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Research

Article
Investigation into Effect of Natural Shellac on the Bonding Strength of Magnesium Substituted Hydroxyapatite Coatings Developed on Ti6Al4V Substrates
Coatings 2021, 11(8), 933; https://doi.org/10.3390/coatings11080933 - 04 Aug 2021
Cited by 1 | Viewed by 399
Abstract
The bioactive and biocompatible properties of hydroxyapatite (HA) promote the osseointegration process. To enhance other bio-functions of HA such as improving the antibacterial property of the implant, increasing the rate of cell proliferation, or improving tissue generation capability, HA is substituted with many [...] Read more.
The bioactive and biocompatible properties of hydroxyapatite (HA) promote the osseointegration process. To enhance other bio-functions of HA such as improving the antibacterial property of the implant, increasing the rate of cell proliferation, or improving tissue generation capability, HA is substituted with many elements such as Zn, Cl, Ba, Fe, Cu, Ag, Sr, F, Na, etc. This study reports development of Magnesium substituted HA (Mg-HA) coatings on Ti6Al4V substrates using the dip coating technique. To improve the adhesion and stability of the coating, an intermediate layer of shellac was applied between the coating and Ti6Al4V substrate. The dip coating process parameters were optimized using the Taguchi technique and it was found that dipping time of 35 s and 13% w/w of shellac concentration provided the maximum bonding strength of 12.5 MPa. The biocompatibility, dissolution, and corrosion study of the developed coating using the optimal parameters obtained were carried out in this study. An improvement in cell growth and cell proliferation was observed in the extract medium prepared from coated substrates. Release of Ca, P and Mg ions from the surface of the coated substrate into the simulated body fluid (SBF) was found to be almost constant which shows the stability of the thin film coating formed. The Mg-HA coated substrate also exhibited better corrosion resistance than the uncoated substrate. Full article
(This article belongs to the Special Issue Synthetic and Biological-Derived Hydroxyapatite Implant Coatings)
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Article
Development of Arabinoxylan-Reinforced Apple Pectin/Graphene Oxide/Nano-Hydroxyapatite Based Nanocomposite Scaffolds with Controlled Release of Drug for Bone Tissue Engineering: In-Vitro Evaluation of Biocompatibility and Cytotoxicity against MC3T3-E1
Coatings 2020, 10(11), 1120; https://doi.org/10.3390/coatings10111120 - 20 Nov 2020
Cited by 8 | Viewed by 787
Abstract
Fabrication of reinforced scaffolds to repair and regenerate defected bone is still a major challenge. Bone tissue engineering is an advanced medical strategy to restore or regenerate damaged bone. The excellent biocompatibility and osteogenesis behavior of porous scaffolds play a critical role in [...] Read more.
Fabrication of reinforced scaffolds to repair and regenerate defected bone is still a major challenge. Bone tissue engineering is an advanced medical strategy to restore or regenerate damaged bone. The excellent biocompatibility and osteogenesis behavior of porous scaffolds play a critical role in bone regeneration. In current studies, we synthesized polymeric nanocomposite material through free-radical polymerization to fabricate porous nanocomposite scaffolds by freeze drying. Functional group, surface morphology, porosity, pore size, and mechanical strength were examined through Fourier Transform Infrared Spectroscopy (FTIR), Single-Electron Microscopy (SEM), Brunauer-Emmet-Teller (BET), and Universal Testing Machine (UTM), respectively. These nanocomposites exhibit enhanced compressive strength (from 4.1 to 16.90 MPa), Young’s modulus (from 13.27 to 29.65 MPa) with well appropriate porosity and pore size (from 63.72 ± 1.9 to 45.75 ± 6.7 µm), and a foam-like morphology. The increasing amount of graphene oxide (GO) regulates the porosity and mechanical behavior of the nanocomposite scaffolds. The loading and sustained release of silver-sulfadiazine was observed to be 90.6% after 260 min. The in-vitro analysis was performed using mouse pre-osteoblast (MC3T3-E1) cell lines. The developed nanocomposite scaffolds exhibited excellent biocompatibility. Based on the results, we propose these novel nanocomposites can serve as potential future biomaterials to repair defected bone with the load-bearing application, and in bone tissue engineering. Full article
(This article belongs to the Special Issue Synthetic and Biological-Derived Hydroxyapatite Implant Coatings)
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Article
Fabrication of Silver- and Zinc-Doped Hydroxyapatite Coatings for Enhancing Antimicrobial Effect
Coatings 2020, 10(9), 905; https://doi.org/10.3390/coatings10090905 - 20 Sep 2020
Cited by 4 | Viewed by 1086
Abstract
This study develops, for the first time, composite coatings based on silver and zinc doped hydroxyapatite in chitosan matrix (AgZnHApCs). The AgZnHApCs composite coatings were prepared by dip coating method. The hydroxyapatite (HAp), biocompatible material for regenerating and strengthening damaged bones were doped [...] Read more.
This study develops, for the first time, composite coatings based on silver and zinc doped hydroxyapatite in chitosan matrix (AgZnHApCs). The AgZnHApCs composite coatings were prepared by dip coating method. The hydroxyapatite (HAp), biocompatible material for regenerating and strengthening damaged bones were doped with silver and zinc ions and coated with chitosan in order to produce a uniform and homogenous coating with biocompatibility and antimicrobial properties. The stability of AgZnHApCs suspensions was evaluated by ultrasound measurements. The value of stability parameters of AgZnHApCs suspension is in good agreement with the value of bidistilled water used as reference fluid. Homogeneously dispersed solutions of AgZnHApCs were synthesized to endeavor to optimize the physico-chemical and biological characteristics of the coatings obtained at room temperature. The AgZnHApCs composite suspension and coatings were analyzed using various investigation techniques, such as X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenylte-2H-tetrazolium bromide) assay and antimicrobial studies. The optical spectroscopy, atomic force microscopy (AFM), metallographic examination and X-ray photoelectron spectroscopy (XPS) on AgZnHApCs composite coatings were also conducted. Cell culture and MTT assays demonstrate that AgZnHApCs composite suspension and coatings have no negative effect on the cell viability and proliferation. The cell morphology was not affected in presence of AgZnHApCs composite suspension and coatings. The antimicrobial assays conducted against Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, and Candida albicans ATCC 90029 microbial strains revealed that both the AgZnHApCs composite suspension and coatings exhibited great antimicrobial properties. Full article
(This article belongs to the Special Issue Synthetic and Biological-Derived Hydroxyapatite Implant Coatings)
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Article
Magnesium Doped Hydroxyapatite-Based Coatings Obtained by Pulsed Galvanostatic Electrochemical Deposition with Adjustable Electrochemical Behavior
Coatings 2020, 10(8), 727; https://doi.org/10.3390/coatings10080727 - 24 Jul 2020
Cited by 5 | Viewed by 1453
Abstract
The aim of this study was to adapt the electrochemical behavior in synthetic body fluid (SBF) of hydroxyapatite-based coatings obtained by pulsed galvanostatic electrochemical deposition through addition of Mg in different concentrations. The coatings were obtained by electrochemical deposition in a typical three [...] Read more.
The aim of this study was to adapt the electrochemical behavior in synthetic body fluid (SBF) of hydroxyapatite-based coatings obtained by pulsed galvanostatic electrochemical deposition through addition of Mg in different concentrations. The coatings were obtained by electrochemical deposition in a typical three electrodes electrochemical cell in galvanic pulsed mode. The electrolyte was obtained by subsequently dissolving Ca(NO3)2·4H2O, NH4H2PO4, and Mg(NO3)2·6H2O in ultra-pure water and the pH value was set to 5. The morphology consists of elongated and thin ribbon-like crystals for hydroxyapatite (HAp), which after the addition of Mg became a little wider. The elemental and phase composition evidenced that HAp was successfully doped with Mg through pulsed galvanostatic electrochemical deposition. The characteristics and properties of hydroxyapatite obtained electrochemically can be controlled by adding Mg in different concentrations, thus being able to obtain materials with different properties and characteristics. In addition, the addition of Mg can lead to the control of hydroxyapatite bioactive ceramics in terms of dissolution rate. Full article
(This article belongs to the Special Issue Synthetic and Biological-Derived Hydroxyapatite Implant Coatings)
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Article
Development of Apatite Nuclei Precipitated Carbon Nanotube-Polyether Ether Ketone Composite with Biological and Electrical Properties
Coatings 2020, 10(2), 191; https://doi.org/10.3390/coatings10020191 - 24 Feb 2020
Viewed by 956
Abstract
We aimed to impart apatite-forming ability to carbon nanotube (CNT)-polyether ether ketone (PEEK) composite (CNT-PEEK). Since CNT possesses electrical conductivity, CNT-PEEK can be expected to useful not only for implant materials but also biosensing devices. First of all, in this study, CNT-PEEK was [...] Read more.
We aimed to impart apatite-forming ability to carbon nanotube (CNT)-polyether ether ketone (PEEK) composite (CNT-PEEK). Since CNT possesses electrical conductivity, CNT-PEEK can be expected to useful not only for implant materials but also biosensing devices. First of all, in this study, CNT-PEEK was treated with sulfuric acid to form fine pores on its surface. Then, the hydrophilicity of the substrate was improved by oxygen plasma treatment. After that, the substrate was promptly immersed in simulated body fluid (SBF) which was adjusted at pH 8.40, 25.0 °C (alkaline SBF) and held in an incubator set at 70.0 °C for 1 day to deposit fine particles of amorphous calcium phosphate, which we refer to as ‘apatite nuclei’. When thus-treated CNT-PEEK was immersed in SBF, its surface was spontaneously covered with hydroxyapatite within 1 day by apatite nuclei deposited in the fine pores and high apatite-forming ability was successfully demonstrated. The CNT-PEEK also showed conductivity even after the above treatment and showed smaller impedance than that of the untreated CNT-PEEK substrate. Full article
(This article belongs to the Special Issue Synthetic and Biological-Derived Hydroxyapatite Implant Coatings)
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Article
Characterization of Nano-Scale Hydroxyapatite Coating Synthesized from Eggshells Through Hydrothermal Reaction on Commercially Pure Titanium
Coatings 2020, 10(2), 112; https://doi.org/10.3390/coatings10020112 - 28 Jan 2020
Cited by 10 | Viewed by 1185
Abstract
Commercially pure titanium (c.p. Ti) is often used in biomedical implants, but its surface cannot usually combine with the living bone. A coating of hydroxyapatite (HA) on the surface of titanium implants provides excellent mechanical properties and has good biological activity and biocompatibility. [...] Read more.
Commercially pure titanium (c.p. Ti) is often used in biomedical implants, but its surface cannot usually combine with the living bone. A coating of hydroxyapatite (HA) on the surface of titanium implants provides excellent mechanical properties and has good biological activity and biocompatibility. For optimal osteocompatibility, the structure, size, and composition of HA crystals should be closer to those of biological apatite. Our results show that the surface of c.p. Ti was entirely covered by rod-like HA nanoparticles after alkali treatment and subsequent hydrothermal treatment at 150 °C for 48 h. Nano-sized apatite aggregates began to nucleate on HA-coated c.p. Ti surfaces after immersion in simulated body fluid (SBF) for 6 h, while no obvious precipitation was found on the uncoated sample. Higher apatite-forming ability (bioactivity) could be acquired by the samples after HA coating. The HA coating featured bone-like nanostructure, high crystallinity, and carbonate substitution. It can be expected that HA coatings synthesized from eggshells on c.p. Ti through a hydrothermal reaction could be used in dental implant applications in the future. Full article
(This article belongs to the Special Issue Synthetic and Biological-Derived Hydroxyapatite Implant Coatings)
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Article
Lithium-Doped Biological-Derived Hydroxyapatite Coatings Sustain In Vitro Differentiation of Human Primary Mesenchymal Stem Cells to Osteoblasts
Coatings 2019, 9(12), 781; https://doi.org/10.3390/coatings9120781 - 21 Nov 2019
Cited by 7 | Viewed by 1128
Abstract
This study is focused on the adhesion and differentiation of the human primary mesenchymal stem cells (hMSC) to osteoblasts lineage on biological-derived hydroxyapatite (BHA) and lithium-doped BHA (BHA:LiP) coatings synthesized by Pulsed Laser Deposition. An optimum adhesion of the cells on the surface [...] Read more.
This study is focused on the adhesion and differentiation of the human primary mesenchymal stem cells (hMSC) to osteoblasts lineage on biological-derived hydroxyapatite (BHA) and lithium-doped BHA (BHA:LiP) coatings synthesized by Pulsed Laser Deposition. An optimum adhesion of the cells on the surface of BHA:LiP coatings compared to control (uncoated Ti) was demonstrated using immunofluorescence labelling of actin and vinculin, two proteins involved in the initiation of the cell adhesion process. BHA:LiP coatings were also found to favor the differentiation of the hMSC towards an osteoblastic phenotype in the presence of osteoinductive medium, as revealed by the evaluation of osteoblast-specific markers, osteocalcin and alkaline phosphatase. Numerous nodules of mineralization secreted from osteoblast cells grown on the surface of BHA:LiP coatings and a 3D network-like organization of cells interconnected into the extracellular matrix were evidenced. These findings highlight the good biocompatibility of the BHA coatings and demonstrate that the use of lithium as a doping agent results in an enhanced osteointegration potential of the synthesized biomaterials, which might therefore represent viable candidates for future in vivo applications. Full article
(This article belongs to the Special Issue Synthetic and Biological-Derived Hydroxyapatite Implant Coatings)
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Graphical abstract

Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

1. Title: Comparative structural and dielectric properties of pure and Li-doped synthetic and bovine bone-derived hydroxyapatite in bulk and thin film form
Authors: T. Tite, I.M. Bogdan, M. Enculescu, A.C. Galca, G. Boni, L. Hrib, G. Aldica, I. Pasuk, G.E. Stan *
Affiliation: National Institute of Materials Physics, RO-077125 Magurele, Romania
Abstract: The close resemblance of hydroxyapatite (HA) to the bone mineral, as well as the ease of fine tuning its functional response (e.g. osteoconductivity) by designed ion-substitutions, made it a material of choice for numerous biomedical applications. The prominent role of HA dielectric features on the biomedical performance (i.e. application of electromagnetic fields can accelerate the healing of bone fractures) has been stressed. HA’s piezoelectricity was advanced as explanation, but this is incompatible with its hexagonal structure. The engineering of HA dielectric properties by intentional compositional and structural alterations could be an alternative, but remained to date mostly unexplored. Lithium could constitute an interesting HA dopant, being able to allow not only the decrease solubility and boost of bone fracture healing, but also to change its dielectric response. In this work, the influence of physical-chemical features on the dielectric properties of simple and Li-doped synthetic and biological (BHA), in both bulk and sputtered film form, has been explored. SEM, EDXS, XRD, FTIR and impedance spectroscopy measurements were carried out. For the films, the structure and dielectric constant were strongly anisotropic and lower in value with respect to the bulk state. Their differences were explained by the different (a-axis or c-axis) preferred orientation. The results showed promises that the application horizon of HA-based ceramics could be expanded.

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