Review Reports

Round 1

Reviewer 1 Report

This manuscript considers changes of the fluidity of artificial lipid membranes in the presence of vanadium complexes with tetradentate Schiff base ligands. Besides computational approaches EPR spectroscopy is used as main method. The authors conclude that the influence of the complexes is stronger in the crystalline phase than in the gel phase.

This work is relevant for improving the use of vanadium in therapeutic applications and thus of interest for the readers of Applied Sciences. Experiments, simulations, and data analysis have been performed according to the current state of the art. The conclusions are supported by experimental evidence.

I recommend revisions as detailed below.  

Details:

1.       Introduction: The authors should explain the expression „APEL“.

2.       Instead of wording like „spectroscopic images of the spin probe“ the authors could use „EPR spectra“

3.       The stability of the vesicles (also upon addition of complexes and spin probes) should be checked, e.g. by dynamic light scattering

4.       The authors should describe accurately whether tau is the rotational correlation time of i) the spin probe, ii) the nitroxide moiety or iii) anything else in this case.

5.       The authors should explain why they did not perform full spectral simulations rather than extracting semi-empirical parameters.

6.       The experimental details of the EPR experiments should be described.

7.       Section 3, first paragraph should be deleted.

8.       Section 3.1: the origin of the lines should be explained.

9.       Table 1: please provide units.

10.   Section 3.2.1: at least some spectra should be presented.

11.   How was tau determined? How the error bars? What is the meaning of the lines in Figs 8,9 etc.?

Author Response

Comments from reviewers have been taken into account as far as possible. The text has been linguistically corrected by a professional translator. Improvements in the quality of some drawings have been taken into account. New drawings Fig. 2, 4 and 5 were made. Descriptions and literature were sorted out. To see the details of the corrections and clarifications please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

The aims and objectives of this manuscript are not well presented.  The background information in the introduction does not clearly demonstrate the motive of this study and the reason why certain organometallic compounds were investigated. It is quite surprising that the authors never mentioned that this current study is a continuation of their previous work published in 2017 entitled;  Impact of Vanadium(IV)-Oxy Acetylacetonate and Vanadium(III) Acetylacetonatel on the DPPC Liposome Membranes: EPR Studies (DOI: 10.12693/APhysPolA.132.52).  Some of the work components and results as reported in this manuscript are the same. The authors need to provide an explanation of what's new in this study. Furthermore, any deductions made in the previous study can be used as a motive for this study. 

Other notable errors identified in this manuscript are as follows;

Inconsistency in the numbering of references e.g. References 43,44, 45, and 46 appears after references 1, 2,3, and 4 on page 1.

The objectives of this study should be written in the introduction, not under Subsection 2 (Material and Methods)

Sigma-Aldrich is now under Merck.

Page 2 Figures 1 and 2 are unnecessary unless otherwise substantiated in the discussion.

Page 3  Vanadium complexes V1, V2, and V3 are not in chronological order.

All Figures need to be improved, low picture quality. 

Figures are not appearing consecutively e.g. Figure 3 appears before Figures 1  and 2. 

The authors cited themselves 4 times 

Author Response

Comments from reviewers have been taken into account as far as possible. The text has been linguistically corrected by a professional translator. Improvements in the quality of some drawings have been taken into account. New drawings Fig. 2, 4 and 5 were made. Descriptions and literature were sorted out. To see the details of the corrections and clarifications please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The manuscript is in a better state than before. However, the authors can still improve on the description of the aims and objectives of this study as mentioned on page 2 line 68. 

Author Response

As recommended by the reviewer, the description of the aims and objectives of this study has been completed and expanded (from the 70th line on page 2).