Fabrication of Biocompatible Polycaprolactone–Hydroxyapatite Composite Filaments for the FDM 3D Printing of Bone Scaffolds

Round 1

Reviewer 1 Report

In this manuscript, the authors propose a technological process to fabricate PCL/HA filament for FDM 3D printing. By modifying the wt.% of HA, the authors evaluate mechanical properties and dielectric constant of filament and layers printed with these filaments. Finally, they show the capability of using these filaments to print bone scaffold with a conventional 3D printer equipment.

3D-Printed Poly(e-Caprolactone)/Hydroxyapatite Scaffolds have already been studied in literature but, novelty here, is about the way to obtain filament compatible with FDM 3D printers.

This paper could have a high interest for the scientific community. However, some minor improvement could be considered by the authors.

• The authors studied mechanical and electrical properties of PCL/HA filament and layers with different HA concentration. This paper could be improved with a clear explanation of their choice to print bone scaffold with HA of 15 and 20 wt.%. Moreover, a clear conclusion about the best condition might be an interesting information for the reader.

 

• The authors claim that no dielectric constant measurements have been done on this PCL/HA composite. Thus, maybe it could be interesting to explain why the knowledge of dielectric constant is relevant for the scientific community. If dielectric constant is an important parameters, did the authors have measured current density of PCL/HA printed layers and analysed insulating properties of such layers?

 

• Some recent studies have been reported on PCL/HA composites for printed bone scaffold. Even, no conventional 3D printers have been used to fabricate these bone scaffold, these studies have to be cited by the authors. 2 examples : Rsc Adv, 2020, 10, 4805-4816 (DOI:10.1039/C9RA10275B) and Polymers 2021, 13, 257 (DOI:10.3390/polym13020257)

 

• Dielectric loss has been measured by the authors but at high frequency (8GHz), the value seems to be negative whereas dielectric losses are always positive. Logarithmic plot of dielectric loss is more relevant because tand is oftenly a low value. Examples : Alumina : 3x10^-4 (@10GHz), Polystyrene 3.3x10^-4(@3GHz), ….

 

• In figure 5, tensile strain curve of fabricated filament and 3D printed layers are plotted. Strain unit is mainly measured in %. Could the authors check the strain unit?

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

The article sounds interesting and the results are well described. Congratulations to the authors for the work.

Author Response

We thank the reviewer for his/her valuable efforts in reviewing our work and appreciate the positive feedback. 

Reviewer 3 Report

I have reviewed the paper titled ‘Fabrication of biocompatible polycaprolactone-hydroxyapatite composites filament for FDM 3D printing of bone scaffold’. First of all, the research is very interesting and I would like to congratulate the authors for their work.

However, I have some concerns about the Additive Manufacturing process itself, the evaluation of the procedure as well as the design of the parts. Therefore, I would like from the authors to elaborate the next comments:

1. In Section 2.2 you declare that printing temperature, bed temperature, layer height etc, were remained constant within your experiments. Why you did not employ other printing parameters in order to examine if you can enhance even further the performance of the AM process?
2. How did you obtain the data for designing the 3D models? You skipped a very crucial and difficult task concerning bioengineering applications. Please provide more details.
3. Did the dimensional accuracy of the 3D printed parts was acceptable? Did you measure it? How much was the dimensional error compared to the 3D digital model? What is the maximum dimensional error concerning such applications?
4. You mention in page 5 that ‘slightly rough’ surface was observed. The surface finish of a part is of highly importance, therefore measurements and quantification of surface finish is necessary.
5. In figure 4, the font sizes of titles of the axis (2θ and Intensity) are big compared to size of the figure and other font sizes of the paper.
6. How many experiments did you conduct to calculate the stress-strain curves in order to secure the reliability and the repeatability of the experimental results?
7. What is the plan for employing these structures on a real application?

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

Overall, the revised article has significantly improved its quality. The authors have properly answered all of comments and questions. Hence, the manuscript can be accepted for publication.

Thank you for your effort to response to my comments.