In-Vivo Corrosion Characterization and Assessment of Absorbable Metal Implants
Round 1
Reviewer 1 Report
This is a well written review on the topic of corrosion of absorbable metal implants in-vivo. The authors have honed in on an area of investigation and product development that is highly topical, with many scientists focused on it.
The review is well organized and first gives a summary of the methods that are established for corrosion control in the literature.
Page 2, Table 1: This is a very useful table that reviews established corrosion control methods. However, what is missing here is any sort of data or results from each of these methods. Specifically, a reader not familiar with the area of research will not know how effective any of these methods are. More importantly, there is no way to judge how these different methods compare among the different references. The authors should consider adding quantitative data perhaps by expanding the table and adding columns that produce such data.
Page 3, Section 3: Emphasizes the need for standards for the evaluation of absorbable materials in-vivo. This section is well written and clear.
Page 5, Line 148: The authors suggest that corrosion rate can be calculated by weight loss or by measuring oxide layer thickness. however, depending on the nature of corrosion, weight loss may not be a reasonable method, since the corroded layer may actually weigh the same or more as the original.
Page 6, Section 4.3: The authors introduce and discuss ultrasonography and radiography. The authors discuss several methods that fall into this category including micro-CT and MRI. Once again, in this section they offer no judgement or differentiation among these methods. The authors should consider ideally presenting quantitative data from the literature to compare and contrast these methods or at least present an idea of what type of quantification they would offer and what has been presented in the literature in this regard. Furthermore, the authors should offer their own impression or judgement as to the feasibility, cost, reliability, and accuracy of any of these methods particularly if they have any experience with any of them.
Page 9, Section 9.2: While this section is very interesting, the authors do not indicate the potential applicability of this system for anything other than strictly research animal studies.
Author Response
Response to Reviewers’ Comments
coatings-480641
We would like to express our gratitude to the Editor and Reviewers for taking your valuable time in reviewing our manuscript. Your comments are very constructive and encouraging. Thank you very much.
The following are our response to your comments. Changes in the manuscript are highlighted in green:
Reviewer 1
This is a well written review on the topic of corrosion of absorbable metal implants in-vivo. The authors have honed in on an area of investigation and product development that is highly topical, with many scientists focused on it. The review is well organized and first gives a summary of the methods that are established for corrosion control in the literature.
Page 2, Table 1: This is a very useful table that reviews established corrosion control methods. However, what is missing here is any sort of data or results from each of these methods. Specifically, a reader not familiar with the area of research will not know how effective any of these methods are. More importantly, there is no way to judge how these different methods compare among the different references. The authors should consider adding quantitative data perhaps by expanding the table and adding columns that produce such data.
== As your suggestion, we expanded Table 1 to provide more details also add more information on figures.
Page 3, Section 3: Emphasizes the need for standards for the evaluation of absorbable materials in-vivo. This section is well written and clear.
== Thank you.
Page 5, Line 148: The authors suggest that corrosion rate can be calculated by weight loss or by measuring oxide layer thickness. However, depending on the nature of corrosion, weight loss may not be a reasonable method, since the corroded layer may actually weigh the same or more as the original.
== We agree with your comment. The weight loss method has a drawback especially when the effect of cleaning is hard to control such as for iron. To obtain a more comprehensive results, weight loss should be complimented with other methods such as potentiodynamic polarization and hydrogen evolution measurement (for magnesium).
Page 6, Section 4.3: The authors introduce and discuss ultrasonography and radiography. The authors discuss several methods that fall into this category including micro-CT and MRI. Once again, in this section they offer no judgement or differentiation among these methods. The authors should consider ideally presenting quantitative data from the literature to compare and contrast these methods or at least present an idea of what type of quantification they would offer and what has been presented in the literature in this regard. Furthermore, the authors should offer their own impression or judgement as to the feasibility, cost, reliability, and accuracy of any of these methods particularly if they have any experience with any of them.
== As your suggestion, we added our opinion in the end of now chapter 3 and 4 to provide more insight of the described methods for the benefit of absorbable metals corrosion studies.
Page 9, Section 9.2: While this section is very interesting, the authors do not indicate the potential applicability of this system for anything other than strictly research animal studies.
== We indicated its potential in the revised manuscript.
Reviewer 2 Report
In my opinion the manuscript being focused as a review on absorbable metals metallurgical characterization and in-vitro corrosion assessment is suitable for publication in Coating journal the topics being new, the material relatively well organized and treated with a large number of references.
For a better organization, may be it is a need for a more quantified presentation of the data, the manuscript having only one table. Also
All the figures have many images with large legends ; it is right that one image is more than 1000 words but what is a bit too much is not in the benefit of the paper
The conclusion is a bit too general The statements such as "The current potential systems for in-vivo corrosion monitoring of absorbable metal implants need further development. Among many potential techniques, it seems promising to further develop a combined system of microelectrode as a biosensor with an analog-digital data acquisition device" are proposed for various biomaterials monitoring and it will be better to introduce more specific details.
However, my recommendation is to be published after revision
Author Response
Response to Reviewers’ Comments
coatings-480641
We would like to express our gratitude to the Editor and Reviewers for taking your valuable time in reviewing our manuscript. Your comments are very constructive and encouraging. Thank you very much.
The following are our response to your comments. Changes in the manuscript are highlighted in green:
Reviewer 2
In my opinion the manuscript being focused as a review on absorbable metals metallurgical characterization and in-vitro corrosion assessment is suitable for publication in Coating journal the topics being new, the material relatively well organized and treated with a large number of references.
For a better organization, may be it is a need for a more quantified presentation of the data, the manuscript having only one table. Also all the figures have many images with large legends; it is right that one image is more than 1000 words but what is a bit too much is not in the benefit of the paper.
== We expanded Table 1 to provide more details also add more information on figures.
The conclusion is a bit too general. The statements such as "The current potential systems for in-vivo corrosion monitoring of absorbable metal implants need further development. Among many potential techniques, it seems promising to further develop a combined system of microelectrode as a biosensor with an analog-digital data acquisition device" are proposed for various biomaterials monitoring and it will be better to introduce more specific details. However, my recommendation is to be published after revision
== We revised the conclusion to provide a more precise statement. Thank you.
Reviewer 3 Report
Referee Report (Coatings-480641)
Title: In-vivo corrosion characterization and assessment of absorbable metal implants
Authors: Mokhamad Fakhrul Ulum, Wahyu Caesarendra, Hendra Hermawan
Article Type: Review
The review article by Ulum et al. addresses the actual problem in the field of the in-vivo corrosion assessments of absorbable metals. Although standards and norms for in-vitro corrosion testing are established (e.g. new ASTM standards F3160 and F3268), in-vivo corrosion testing and its setting are still questionable. The aim of the presented manuscript consisting of six chapters is to provide fundamentals and to summarize methods and techniques actually used in the in-vivo corrosion assessments and to present new methods which could be potentially used.
The first chapter introduces the reader into the bioabsorbable metals and describes properties which these materials should meet. The second chapter provides some principles applied to corrosion rate control. The third chapter compares in-vitro and in-vivo methods used to corrosion rate measurements and their general drawbacks and discusses the problem of mimicking real body environment in the experimental set-up. Authors also point out the need for finding a correlation between in-vitro and in-vivo methods and say that even newly established norms include only in-vitro assessments. Both, fourth and fifth chapters provide actual in-vivo techniques which could be used for corrosion studies. At the end of the article, authors state that further work is needed in this research area and also propose in their opinion the most suitable method for in-vivo corrosion testing.
The proposed review article is dealing with the actual problem and I find author´s effort to set a common ground beneficial for researchers dealing with the same scientific problems and also for readers who are new in the biomaterial research. I had no trouble to follow the text because text divisions are reasonably linked and continuous and the text is easy to read in general. Nevertheless, there are some points that need to be considered:
Major points
Ø in the second chapter, authors briefly discuss possibilities of corrosion control techniques, typically used methods and their effects. The nature of the problem is extensive and so is the number of studies and results in the area which could not be reduced to this extent. The examples do not reflect the over-all research made in the area and therefore could be confusing for less experienced readers. I am not sure that the second chapter is, in this case, that important to make a whole separate division. Authors should consider merging the second chapter into the third chapter (e.g. as a sub-division).
Minor points
§ p.3, line 103: „...protein absorption...“ should be corrected to „adsorption“ or explained if meant otherwise
§ p.3, line 106-108: the sentence should be simplified or divided into two smaller parts for better understanding
§ p. 4, line 134: „Adsorption of organic molecules such as albumin onto the magnesium surface delays its corrosion process in the initial stage [50]...“ There is evidence that albumin adsorption enhances corrosion rate of stainless steel what I suggest to mention.
§ p.9. line 267: „...as capillary pH and Mg2+sensors...“ a space between „Mg2+“ and „sensors“ is missing
§ p.10, line 314-315: In this sentence: „...required to validate the idea and it utilization ...“ „it“ should be replaced with „its“
On the basis of the arguments provided before I recommend this article to be accepted after minor revision that needs to be done.
Author Response
Response to Reviewers’ Comments
coatings-480641
We would like to express our gratitude to the Editor and Reviewers for taking your valuable time in reviewing our manuscript. Your comments are very constructive and encouraging. Thank you very much.
The following are our response to your comments. Changes in the manuscript are highlighted in green:
Reviewer 3
The review article by Ulum et al. addresses the actual problem in the field of the in-vivo corrosion assessments of absorbable metals. Although standards and norms for in-vitro corrosion testing are established (e.g. new ASTM standards F3160 and F3268), in-vivo corrosion testing and its setting are still questionable. The aim of the presented manuscript consisting of six chapters is to provide fundamentals and to summarize methods and techniques actually used in the in-vivo corrosion assessments and to present new methods which could be potentially used.
The first chapter introduces the reader into the bioabsorbable metals and describes properties which these materials should meet. The second chapter provides some principles applied to corrosion rate control. The third chapter compares in-vitro and in-vivo methods used to corrosion rate measurements and their general drawbacks and discusses the problem of mimicking real body environment in the experimental set-up. Authors also point out the need for finding a correlation between in-vitro and in-vivo methods and say that even newly established norms include only in-vitro assessments. Both, fourth and fifth chapters provide actual in-vivo techniques which could be used for corrosion studies. At the end of the article, authors state that further work is needed in this research area and also propose in their opinion the most suitable method for in-vivo corrosion testing.
The proposed review article is dealing with the actual problem and I find author´s effort to set a common ground beneficial for researchers dealing with the same scientific problems and also for readers who are new in the biomaterial research. I had no trouble to follow the text because text divisions are reasonably linked and continuous and the text is easy to read in general. Nevertheless, there are some points that need to be considered:
Major points
Ø in the second chapter, authors briefly discuss possibilities of corrosion control techniques, typically used methods and their effects. The nature of the problem is extensive and so is the number of studies and results in the area which could not be reduced to this extent. The examples do not reflect the over-all research made in the area and therefore could be confusing for less experienced readers. I am not sure that the second chapter is, in this case, that important to make a whole separate division. Authors should consider merging the second chapter into the third chapter (e.g. as a sub-division).
== We agree with you and merged the chapters. Thank you.
Minor points
§ p.3, line 103: „...protein absorption...“ should be corrected to „adsorption“ or explained if meant otherwise
== Corrected. Thank you.
§ p.3, line 106-108: the sentence should be simplified or divided into two smaller parts for better understanding
== The sentence is rewritten.
Reviewer 4 Report
I congratulate the authors for the contribution brought on this hot topic: “absorbable metals”. They have offered some valuable information on this topic in terms of “in vivo corrosion and assessment”. Nevertheless, below the authors can find some remarks as following:
· I kindly ask the authors to acknowledge that they have permission to use the images presented in Figure 2, 3, 4, 5, 6, 7 and 8 as mentioned in the “Publication Ethics Statement” section found in “Coatings — Instructions for Authors”;
· Table 1 – For the last 2 examples (AZ31 and ZMZ21) please add the types of medium used in the presented studies. Also, please add the technique of corrosion test achieved for each example presented in Table 1;
· Line 60 – In the following paragraph (“corrosion rate of iron-based metals was increased by alloying, such as with manganese, palladium, silver, gallium, sulfur and intermetallics [6,18-21], …), the authors mention “intermetallic” – what intermetallics are the authors referring to?
· Some paragraphs need some adjustments for e.g.: line 58-64;
· In my opinion, probably the authors when using “metallurgy” (line 90), “metallurgical inhomogeneity” (line 115) are referring to some metallurgical properties/characteristics/aspects, so, in this light the authors are invited to indicate the exact property/characteristic/aspect that are referring to (eg.: microstructure, microstructural inhomogeneity, etc.). This remark is available for the entire manuscript;
· Nevertheless, the manuscript requires some improvements in terms of scientific discussion, because sometimes just results are presented (section 4 and 5). In order to enhance the manuscript and give a higher scientific soundness I kindly ask the authors to add their opinion through their experience in the absorbable biomaterials field and to enhance the discussion parts in section 4 and 5.
If you are submitting a revised manuscript, please also:
a) outline each change made (point by point) as raised in the reviewer comments,
b) highlight all the changes made to the manuscript in color so that they are easily seen by the editors/reviewers
Author Response
Response to Reviewers’ Comments
coatings-480641
We would like to express our gratitude to the Editor and Reviewers for taking your valuable time in reviewing our manuscript. Your comments are very constructive and encouraging. Thank you very much.
The following are our response to your comments. Changes in the manuscript are highlighted in green:
Reviewer 4
I congratulate the authors for the contribution brought on this hot topic: “absorbable metals”. They have offered some valuable information on this topic in terms of “in vivo corrosion and assessment”. Nevertheless, below the authors can find some remarks as following:
- I kindly ask the authors to acknowledge that they have permission to use the images presented in Figure 2, 3, 4, 5, 6, 7 and 8 as mentioned in the “Publication Ethics Statement” section found in “Coatings — Instructions for Authors”;
== Permission for all figures are granted.
- Table 1 – For the last 2 examples (AZ31 and ZMZ21) please add the types of medium used in the presented studies. Also, please add the technique of corrosion test achieved for each example presented in Table 1;
== Types of medium are added and the Table is modified to include more details.
- Line 60 – In the following paragraph (“corrosion rate of iron-based metals was increased by alloying, such as with manganese, palladium, silver, gallium, sulfur and intermetallics [6,18-21], …), the authors mention “intermetallic” – what intermetallics are the authors referring to?
== We were referring to intermetallics compounds such as Mg2Si (Ref. 21).
- Some paragraphs need some adjustments for e.g.: line 58-64;
== We modified the paragraph to add more important details.
- In my opinion, probably the authors when using “metallurgy” (line 90), “metallurgical inhomogeneity” (line 115) are referring to some metallurgical properties/characteristics/aspects, so, in this light the authors are invited to indicate the exact property/characteristic/aspect that are referring to (eg.: microstructure, microstructural inhomogeneity, etc.). This remark is available for the entire manuscript;
== We gladly follow your suggestion to be more precise with the use of metallurgical terms.
- Nevertheless, the manuscript requires some improvements in terms of scientific discussion, because sometimes just results are presented (section 4 and 5). In order to enhance the manuscript and give a higher scientific soundness I kindly ask the authors to add their opinion through their experience in the absorbable biomaterials field and to enhance the discussion parts in section 4 and 5.
== We are grateful to fulfill your request and added our opinion in section 4 and 5.
If you are submitting a revised manuscript, please also:
a) outline each change made (point by point) as raised in the reviewer comments,
b) highlight all the changes made to the manuscript in color so that they are easily seen by the editors/reviewers
== Done.
