Synthesis of Magnesium-Based Alloys by Mechanical Alloying for Implant Applications

Round 1

Reviewer 1 Report

1）MA may introduce some impurity to the alloy, the author should make a detail analysis to the composition of the alloy.

2） The degradation  speed is crucial to the biodegradable alloy. The author only determined the corrosion current without discussion which speed is a suitable value to the implant.

Author Response

We sincerely appreciate the time and careful reading by the editor and reviewer. We addressed all the comments listed and have made corresponding changes to our revised manuscript. Details of our replies to the comments are the following:

 

1）MA may introduce some impurity to the alloy, the author should make a detail analysis to the composition of the alloy.

Detail analysis has been added in the text.

 

2） The degradation speed is crucial to the biodegradable alloy. The author only determined the corrosion current without discussion which speed is a suitable value to the implant.

The degradation speed is state in the manuscript and a brief discussion on the speed. Which is suitable value to the implant.

Reviewer 2 Report

 

This work synthesized two alloys of Mg/Zn/Ca using mechanochemistry method and characterized the physical and chemical properties of the obtained samples. I would suggest a major revision on the following aspects.

1.     Elemental analyses in Table 3 showed the composition of the alloy did not follow the ratio of input elemental powders so I would suggest change the sample name Mg65-Zn30-Ca5 to something like Mg68-Zn31-Ca1 to better reflect the correct elemental composition and avoid confusion.

2.     The MA process utilized stainless-steel balls. Did EDS detect any residual Fe, Cr, Mn, Ni, C or other elements from the stainless steel or O due to oxidation? If so, how much were these additional elements? Were they expected to induce any toxicity?

3.     Why was Ca not well incorporated into the alloy? Based on Table 3 only about 12% of the added Ca got into the alloy.

4.     Figure 6 and 7, the peak around 35° seemed to be a consistent peak from 2 h to 20 h but was labeled differently. In 2 h sample it was labeled as Mg and Zn but in 20 h sample it was MgZn. Please clarify.

5.     What were the reasons to select Mg/Zn/Ca 65:30:5 and 70:25:5 as the initial weight ratio?

6.     Between the two synthesized alloys, could the authors suggest which one is better for clinical application?

Author Response

We sincerely appreciate the time and careful reading by the editor and reviewer. We addressed all the comments listed and have made corresponding changes to our revised manuscript. Details of our replies to the comments are the following:

1. Elemental analyses in Table 3 showed the composition of the alloy did not follow the ratio of input elemental powders so I would suggest change the sample name Mg65-Zn30-Ca5 to something like Mg68-Zn31-Ca1 to better reflect the correct elemental composition and avoid confusion.

It has been corrected.

 

2. The MA process utilized stainless-steel balls. Did EDS detect any residual Fe, Cr, Mn, Ni, C or other elements from the stainless steel or O due to oxidation? If so, how much were these additional elements? Were they expected to induce any toxicity?

An explanation has been added in the text.

 

3. Why was Ca not well incorporated into the alloy? Based on Table 3 only about 12% of the added Ca got into the alloy.

It has been state in the text.

 

4. Figure 6 and 7, the peak around 35° seemed to be a consistent peak from 2 h to 20 h but was labeled differently. In 2 h sample it was labeled as Mg and Zn but in 20 h sample it was MgZn. Please clarify.

It has been corrected.

 

5. What were the reasons to select Mg/Zn/Ca 65:30:5 and 70:25:5 as the initial weight ratio?

It has been corrected.

 

6. Between the two synthesized alloys, could the authors suggest which one is better for clinical application?

It has been state in the text.

Reviewer 3 Report

Phase symbols in fig. 6-8 are placed incorrectly. For example, for zinc, there are no diffraction reflexes within the angles 2 theta 32-35. Please correct the phase analysis.

  If it is possible please add to supplemental materials the SEM elemental mapping.

The standard deviation for the content of each element in Table 3 should be given.

Author Response

We sincerely appreciate the time and careful reading by the editor and reviewer. We addressed all the comments listed and have made corresponding changes to our revised manuscript. Details of our replies to the comments are the following:

1. Phase symbols in fig. 6-8 are placed incorrectly. For example, for zinc, there are no diffraction reflexes within the angles 2 theta 32-35. Please correct the phase analysis.

Phase symbols have been corrected.

 

2. If it is possible, please add to supplemental materials the SEM elemental mapping.

SEM elemental mapping has been included in supplemental materials.

 

 

3. The standard deviation for the content of each element in Table 3 should be given.

The standard deviation has been included.

Reviewer 4 Report

Micrographs and images in general should be improved

- Figure 6. XRD patterns of Mg65-Zn30-Ca5 mechanically alloyed for milling times of 2, 5, 10, 15, and 20 h. It must be indexed correctly, the same peak cannot have two different elements, in addition, the PDF must be included.

- 3.4. Cytotoxicity test, the disadvantage of the method used (SRB) is that there is no difference between live and dead cells and only measures the amount of protein, so it would be advisable to use another method of comparison as MTT-MTS-WTS, among others to validate the results.

The bibliography should be more current

 

 

Author Response

We sincerely appreciate the time and careful reading by the editor and reviewer. We addressed all the comments listed and have made corresponding changes to our revised manuscript. Details of our replies to the comments are the following:

1. Micrographs and images in general should be improved

Micrographs and images have been improved.

 

2. Figure 6. XRD patterns of Mg65-Zn30-Ca5 mechanically alloyed for milling times of 2, 5, 10, 15, and 20 h. It must be indexed correctly, the same peak cannot have two different elements, in addition, the PDF must be included.

XRD patterns have been corrected.

 

3. Cytotoxicity test, the disadvantage of the method used (SRB) is that there is no difference between live and dead cells and only measures the amount of protein, so it would be advisable to use another method of comparison as MTT-MTS-WTS, among others to validate the results.

The justification for Cytotoxicity has been included in the text.

 

4. The bibliography should be more current

The bibliography has been updated.

Round 2

Reviewer 1 Report

The paper has been improved and meet the standard of the present journal.

Author Response

Thank you very much, we appreciate your time and careful reading.

Reviewer 4 Report

The authors addressed most of the comments but are again encouraged to

Figures 2, 4, 12 to improve the quality

  Figures 6, 7, 8. should include PDFs.

The bibliography should be more current

Author Response

Thank you very much, we be grateful for the time and careful reading of the manuscript. We addressed the comments listed and have made corresponding changes to our revised manuscript. Details of our replies to the comments are the following:

• The authors addressed most of the comments but are again encouraged to Figures 2, 4, 12 to improve the quality

 Figures 2, 4 and 12 have been improved the quality.

• Figures 6, 7, 8. should include PDFs.

PDFs have been included in the manuscript.

• The bibliography should be more current

We have already carried out a careful review of the state of the art of the subject of the work and we have previously added 10 current references, which we believe is enough.