Wetting Properties of Polyetheretherketone Plasma Activated and Biocoated Surfaces
Round 1
Reviewer 1 Report
This manuscripts investigate the interfacial properties of polyetheretherketone after plasma treatment and after deposition of a mixture of a lipid, a phospholipid, and a peptide, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), cholesterol (Chol), and cyclosporine A (CsA).
1) Introduction should include more about existing works on the deposition of lipid bilayers and biofilm on implant surfaces in general. There is a significant amount of literature on this topics.
2) Section 3.1 should be divided into 2 or 3 paragraphs. Perhaps contact angle for each liquid can be a paragraph.
3) Advancing and receding contact angles are given. However, the static contact angle measurements with respect to time is not provided. These studies can provide further insights into the robustness of the coating.
4) Langmuir-Blodgett technique is used to prepare thin films involving a lipid, a phospholipid, and a peptide. However, no pressure-area isotherms are shown. Without knowing 2-D phase diagrams, it is not possible to understand the nature of films forming.
5) The surfaces should also be investigated with atomic force microscopy. Because it is well-known that the surface roughness can influence the contact angle. For instance, plasma treatment can alter the surface roughness.
Overall, this article deals with the advancing and receding contact angles of a modified polymer surface with and without biofilm for potential implant applications. Some of the important characterization aspects are missing. Hence, I recommend this work for publication after addressing abovementioned issues and concerns.
Author Response
Response in the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The manuscript brigns interesting results regarding surface modifications of PEEK. The experimental methods are well described and the data well discussed. The captions of the x-axys of the graphical figures could be enlarged, because sometimes they are difficult to read.
Author Response
Response to Reviewer #2
The manuscript brigns interesting results regarding surface modifications of PEEK. The experimental methods are well described and the data well discussed. The captions of the x-axys of the graphical figures could be enlarged, because sometimes they are difficult to read.
We would like to thank you very much for your helpful suggestion. We introduced suitable changes in the graphs. I hope that now the new figures are more legible.
Round 2
Reviewer 1 Report
As of now, the manuscript mostly gives information about contact angle of water and DIM on various lipid-coated PEEK surfaces and the corresponding surface energies. The introduction section is improved and includes a better representation of the state of the art. However, the data shown in the manuscript is hard to interpret without the pressure-area data was shown in the response letter (the authors state that that part of the data was submitted to another journal and cannot be used in this manuscript). Also, surface roughness can be measured with another technique (instead of AFM) such as optical profilometry or even SEM microscopy can give an idea about the surface texture (while it may not be quantitative). The reviewer believes that at least surface texture characterization should be given for the data to support the conclusions to some extent. Hence, I request this journal for publication only after addressing this issue.
Author Response
Reply to the Reviewer enclosed in the attachment.
Author Response File: Author Response.pdf
