Bioactive Calcium Phosphate Coatings for Bone Implant Applications: A Review
Round 1
Reviewer 1 Report
The authors are asked to view the attached annotated manuscript and comply witht he suggestions made therein. In particular, missing deposition methods ought to be added and discussed. These methods include suspension (SPS) and solution precursor plasma spraying (SPPS), hydrothermal deposition, biomimetic and sol-gel deposition, chemical vapour deposition (CVD) and others.
Comments for author File: 
Comments.pdf
Author Response
The authors sincerely thank Reviewer #1 for the careful remarks and relevant comments to improve the quality of our manuscript. Our review has been revised accordingly. The corresponding modifications and our answers are highlighted in yellow in the documents.
In particular:
- The introduction has been improved by removing the sentences that repeat the abstract and by introducing new deposition methods which are biomimetic deposition, sol-gel process combined with dip or spin coating, and hydrothermal synthesis.
- Table 1 has been modified by moving the Ca/P column to the left-hand side.
- In section 3.1, the non-linearity of plasma spray deposition has been described. The description of cracks, P2O5, and dissolution behavior has been improved. The plasma spray deposition variants suspension plasma spraying (SPS) and solution precursor plasma spraying (SPPS) are now described.
- In section 3.4, the mechanism of ESD is now described more accurately.
- A new section 3.6 dealing with biomimetic deposition has been added, including a new figure.
- A new section 3.7 dealing with the sol-gel process combined with dip or spin coating has been added, including a new figure.
- In section 3.8 dealing with electrodeposition, the use of hydrogen peroxide to produce stoichiometric hydroxyapatite has been added to the text.
- A new section 3.9 dealing with hydrothermal synthesis has been added, including a new figure.
- The section 4.2 on the morphology of calcium phosphate coating has been improved.
- A new section 4.4 dealing with the porosity of calcium phosphate coatings has been added.
- In section 4.6 dealing with the adhesion of calcium phosphate coatings, the methods peel test, scratch test, ultrasonic test, and laser shock adhesion test have been added, including relevant references to these methods.
However:
- The description of all the deposition methods in a row has been kept, with no separation between thermal and non-thermal methods. Our idea is to describe first plasma spraying which is the main industrial method, and then some alternative deposition processes that are currently in development in academic research and industry.
- Figures 8 and 12 (now #15) have been kept because we think they are necessary to fully understand the electrophoretic deposition process and visually describe what wettability is for readers who are not familiar with this characterization method.
Reviewer 2 Report
This review is very interesting, in fact it summarizes all the methods of calcium phosphate deposition and the chemical reactions present. This work is original because in literature there is no such thing. The strength of the work is to cite 281 references, but at the same time make a very good summary short but very detailed. The choice of figures is excellent, as they manage to make a fairly complex process in a schematic way.In fact, they use figures from other jobs in order to choose the most convincing ones. The two tables present give a perfect idea of the large amount of information present in the literature, but the authors also present us here, a brief overview with always present the bibliographic citations. The strength of this paper is the large amount of information present, but at the same time, the reader in a short time has an overview and the possibility to deepen using all the references mentioned. Considering that this work fills a gap in the literature present in recent years, it deserves to be published.Good quality
Author Response
The authors sincerely thank Reviewer #2 for the positive comments on the quality of our manuscript. We hope that our review will be accepted for publication soon and available for the readership of the journal Coatings.
Reviewer 3 Report
There are a lot of articles are missed on hydroxyapatite like
Effect of chitosan structure and deposition time on structural and mechanical properties of chitosan-hydroxyapatite tubular-shaped electrodeposits for biomedical applications
And others like this
Electrochemical and hydrogen evolution behaviour of a novel nano-cobalt/nano-chitosan composite coating on a surgical 316L stainless steel alloy as an implant, International Journal of Hydrogen Energy, , (2021)
2- Plasma electrolytic oxidation coatings on femtosecond laser-treated Ti-6Al-4V alloy for bio-implant use, Surface and Coatings Technology, Volume 464, 15 July 2023, 129553.
3- Fretting tribocorrosion properties of anodized TiNbSn implant alloy, Surface and Coatings Technology, Volume 462, 15 June 2023, 129492
And others
it is good
Author Response
The authors sincerely thank Reviewer #3 for the careful remarks and valuable comments to improve the quality of our manuscript. Our review has been revised accordingly. Several new deposition methods have been described, including 25 new relevant references. The biomimetic deposition is described in section 3.6, the sol-gel process combined with dip or spin coating is described in section 3.7, and the hydrothermal synthesis is described in section 3.9. The introduction has been modified accordingly. Calcium carbonates are not in the scope of our review that focuses on calcium phosphates. The section dealing with electrodeposition has been improved by adding information on the use of hydrogen peroxide to produce stoichiometric hydroxyapatite coatings.
Round 2
Reviewer 1 Report
The contribution has been successfully revised. In particular, all suggestions and queries by this reviewer have been addressed satisfactorily.
