Round 1

Reviewer 1 Report

In the introduction and in view of the gradient of porosity it could be intereting to report on the work by Baino et al. Mechanical characterization of pore-graded bioactive glass scaffolds produced by robocasting

“Then, ball-milled HA powder was added to the mixture in small amounts” The M&M should permit others to replicate the work (to some extent). This is unclear and the amount of HA introduce in the gel should be clearly stated (in m% or V%) here… Maybe part of the Table 1 should be added here.. or reference to table 1 made.

The average por size was estimated at 275µm … How was this measure since the pore is not spherical and the lattice while being equal in x and y was smaller in z direction? Also while a porosity of 34% is within the value typically reported, with such big pore the reviewer would have expected slightly higher porosity, in the order of 45%.

One question is: why did the lattice structure was made as a rectangle while the dense and bi layer one spherical… for clatter comparison it would have been beneficial to maintain the geometry constant

“…confirming in vitro osteoconductivity of the samples.” This sentence seems to this reviewer over interpreted. Osteoconduction cannot be only assessed through SBF testing. One can say that the precipitation of the reactive layer is a first sign of bioactivity but in-vitro cell test must be added to confirm bioactivity and osteoconductivity.

This reviewer is not sure to understand if the precipiatate has been imaged at the surface /periphery of the material or within the pores… It could be beneficial to clarify this point and maybe show a cross section of the scaffolds to show whether or not the precipitate is only at the surface or also within the core/center of the scaffolds

Overal the paper is elegant and interesting. Only minor suggestion are proposed

Author Response

Dear Editor,

Dear Reviewer,

 

Thank you for your advice and useful comments, which were very useful to improve the quality of the work, and made it more appreciated by potential readers.

Please find in the attached file the detailed answer to reviewer’s comments. Moreover, all the corrections in the revised manuscript were done while the Microsoft Word track change tool was enabled, so you will find them in a different color.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments for the authors

Major Comments

The paper is well written and focuses on a novel way to produce antibacterial grafts. However, the paper is lacking to address some vital points.

1. No studies except mechanical and surface characterization have been performed on the grafts. The bioavailability and biodegradation of the scaffolds are key factors that the authors mention are key for bone grafts. However, this has not been tested. Using biodegradable materials and using biomaterials that have previously used before does not guarantee the bioavailability, suitable biodegradation rates and adhesion of cells to the scaffold. These tests need to be conducted in vitro before it can be claimed to be called bone grafts.
2. The lack of vascularization in bone grafts is the major reason for the failure of bone grafts. The paper does not acknowledge this major hurdle in fabrication of bone grafts.
3. The crystalline phase at which the CaP is present determines its properties. The authors need to characterize this.

The authors are encouraged to go over such articles that discuss CaP ceramics.

Samavedi, Satyavrata, Abby R. Whittington, and Aaron S. Goldstein. "Calcium phosphate ceramics in bone tissue engineering: a review of properties and their influence on cell behavior." Acta biomaterialia 9.9 (2013): 8037-8045.

4. Adequate statistical analysis has not been provided in the data analysis. This is a must and the authors can follow ASTM or ISO standards
5. The current work does not improve the scientific knowledge and further experiments are needed to justify the publication of the manuscript.
6. Creep stress and other mechanical characterizations need to be performed. Uniaxial and compression testing does not guarantee the performance of the material over a period of time.

 

Minor revisions

1. Check the document for grammatical errors and punctuation marks
2. Calcium phosphate materials is a misleading statement in the line 48.
3. Please rephrase line 50. It is misleading. ‘Supply proper cell attachment’ is misleading.
4. Referencing a book (reference 10) for such a debatable statement in line 53 should be avoided.

 

Author Response

Dear Editor,
Dear Reviewer,

Thank you for your advice and useful comments, which were very useful to improve the quality of the work, and made it more appreciated by potential readers.
Please find in the attached file the detailed answer to the reviewer’s comments. Moreover, all the corrections in the revised manuscript were done while the Microsoft Word track change tool was enabled, so you will find them in a different color.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Comments to the Authors

Minor Comments

1. Minor spelling and grammar check required.
2. Line 240 – chemical symbol
3. Line 272- Student’s t- test and not T-Student test.
4. Table 2: The pore size reads 600-1040. Can you please check the values discussed in the paper?

 

Major Comments

The reviewer appreciates the changes made by the authors and would like to weigh in on some key points in order to improve the research.

• The authors again have failed to justify why these ‘novel scaffolds’ can be used as a bone implant as opposed to a stainless-steel plate coated with silver nanoparticles. A scaffold in tissue engineering refers to something that can support growth of cells. The novelty of the technique and the fabrication method is well written; however, the application of the scaffold has not been highlighted or tested.
• In vitro bioactivity assays using S. aureus definitely shows the antibacterial aspect of the scaffold but the real problem with grafts or bone implants is the fine line between degradation and mechanical support provided by the scaffolds. The authors have not addressed this. There have been numerous reports on the use of Ag ions and their antibacterial activity and hence, this is not something novel that needs to be reported but further researched upon to provide more detailed information to weigh in to the scientific knowledge of the research community.
• The authors have misunderstood what creep tests and other suggested mechanical tests are for. It is to understand the functionality of the implant after degradation. This is essential.

Author Response

Dear Editor,
Dear Reviewer,

Thank you for your advice and useful comments, please find in the attached file the detailed answer to the reviewer’s comments. Moreover, all the corrections in the revised manuscript were done while the Microsoft Word track change tool was enabled, so you will find them in a different color.

Author Response File: Author Response.docx

Round 3

Reviewer 2 Report

The reviewer would like to thanks the authors for clarifying the concepts discussed.