Simulations of Extrusion 3D Printing of Chitosan Hydrogels
Md Ahasan Habib
Round 1
Reviewer 1 Report
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Author Response
Dear Editors and Referees,
Thanks for your letter and for the referees’ comments concerning our manuscript, the manuscript has been revised as the attachment files.
Best regards
Sincerely yours
Dr. Yong He
Reviewer #1
Response: We express sincere thanks to the reviewer for the evaluation of our work.
Reviewer 2 Report
Although the authors have done a lot of work and put some effort into it, I do not consider the article suitable for publication for the following reasons:
- The printability of the chitosin material is modeled using velocity and viscosity variables. However, other parameters that affect printing (e.g. not only the temperature (viscosity) of the material, but also the temperature of the printing substrate) are not mentioned. Also, due to changing ambient conditions, it is not realistically possible to keep the ambient parameters stable and hence these parameters are highly idealised.
- The result of the model is the extrusion of the material from the nozzle. However, the adhesion of the material to the substrate is also important for bioprinting. Thus, it cannot be said that a material that is well extruded from the nozzle will produce a good quality model. Similarly, the subsequent hardening and crosslinking of the material is not factored into the result.
- The paper's conclusions, as stated by the authors, are not innovative. These statements, while true, are familiar to anyone involved in bioprinting.
- Nor do I see a specific contribution of the article. The authors make no recommendations on how to set up a printer or modify the material, they merely state that simulation can predict the outcome of bioprinting. In theory, they could then add an app as an appendix to the article where the reader could test their own print. However, for the reasons stated above, I personally distrust simulations and prefer test prints.
- If the article were to be of use to the scientific community, I would elaborate more on the experimental test that would form the core of the article. CFD simulations do not have much use in this area.
Author Response
Dear Editor and Referee,
Thanks for your letter and for the referees’ comments concerning our manuscript, the manuscript has been revised as the attachment files.
Best regards
Sincerely yours
Prof. Yong He
Author Response File: 
Author Response.pdf
Reviewer 3 Report
This paper covers a very important and interesting topic of mathematical modeling and predicting bioink printability. However, the text requires thorough re-writing. Please, ask native English speakers with good language skills to read the text and suggest corrections. There are many typos, not accurate sentences, and statements that are difficult to understand and follow. In general, in the current form of the text is not presenting the value of the performed research, which in my opinion is very high.
Please, also add the justification why chitosan was chosen as a model material – not yet convincing enough. Also, comment on which other materials and material types your results could be transferred/relevant.
Author Response
Dear Editor and Referee,
Thanks for your letter and for the referees’ comments concerning our manuscript, the manuscript has been revised as the attachment files.
Best regards
Sincerely yours
Prof. Yong He
Author Response File: Author Response.pdf
Reviewer 4 Report
Simulations of extrusion 3D printing of chitosan hydrogels
This study Multiphysics simulation is used to predicate the potential printability of chitosan hydrogel, as a desirable biomaterial used in tissue engineering. The flow is assumed laminar and two-phase in the simulations. It studies the effect of different velocities and viscosities in extrusion-based chitosan 3D printing. Furthermore, the model validation of printed chitosan hydrogel is investigated to verify the simulation results for high-quality printing. The effect of different printing settings is studied during the experimental test. Therefore, the results obtained from the simulation and experiments provide information to choose the best parameters for printing chitosan-based ink with high quality.
Suggestions/Inquiries
1. Line 29-please remove one “several areas”, consider re-writing the sentence.
2. Please elaborate the following sentence, since this is the main purpose of this paper:
“The main purpose of these simulations is to theoretically show the extrusion formation of chitosan 3D printing.”
3. Confusing sentences:
Their viscosity properties depend on the shear rate such as non-Newtonian fluids, for example.
Some parameters will affect the motion, such as the surface tension, viscosity and velocity, 80 for example.
Like such as and for example were used altogether.
4. It is much convenient to calculate the curvature and surface tension forces. and control the formation of an extrusion fluid from the nozzle.
Do remove the period (.), used in between “forces and”
5. Th effect of print distance to filament formation needs to be elaborated.
6. Figure 10(C) represents an intersection of a bi-layer where authors claimed a high quality print referring Figure 10 (F) which is not clear. Pore size and geometry needs to be added to claim high quality shape fidelity.
7. Moreover, I am not seeing relating section 4.2.3 Printability results of chitosan hydrogel to the simulation authors developed. Clarification of the relationship between section 4.2.3 and simulation outcome is highly recommended.
Author Response
Dear Editor and Referee,
Thanks for your letter and for the referees’ comments concerning our manuscript, the manuscript has been revised as the attachment files.
Best regards
Sincerely yours
Prof. Yong He
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Thank you for revising the paper, which is now significantly enriched with valuable data and is thus a good basis for further applications. I now find the article suitable for publication.
Reviewer 3 Report
Comments have been addressed properly.
