FT-IR Characterization of Antimicrobial Hybrid Materials through Sol-Gel Synthesis
Round 1
Reviewer 1 Report
During the recent years the same group has explored successfully a number of related materials; materials fabrication and characterization presented herein is along the previous lines and satisfactory.
HAP formation in SBF is a standard test properly used herein for the question of bioactivity. As regards antimicrobial effectiveness an elementary test/ assessment focused on the case of. E coli is presented.
Overall this is a short and relatively simple work properly presented; it does contain a reasonable amount of useful information and can be published.
Author Response
Dear Editor,
First of all, thank you very much for giving us the possibility to revise and ameliorate our paper.
Please, find enclosed the revised version of the manuscript, as well as our response to the Reviewer's comments.
As required, we have addressed the points raised by the Reviewers and have completed the revision process. Accordingly, we are resubmitting a new version to go back to the Reviewers for re-evaluation.
Once again thanks a lot for your kind attention and assistance.
We do hope the revised manuscript will definitively meet the criteria for publication in Applied Sciences Journal.
Best regards,
Michelina Catauro,
Corresponding author
Reviewer 1
During the recent years the same group has explored successfully a number of related materials; materials fabrication and characterization presented herein is along the previous lines and satisfactory.
HAP formation in SBF is a standard test properly used herein for the question of bioactivity. As regards antimicrobial effectiveness an elementary test/ assessment focused on the case of. E coli is presented.
Overall this is a short and relatively simple work properly presented; it does contain a reasonable amount of useful information and can be published.
The authors are grateful to the reviewer for his/her positive comments.
Reviewer 2 Report
The manuscript requires strong improvements both in terms of presentation of scientific data and in terms of novelty of the work. Moreover, it requires extensive editing of writing style and English language. Please, provide at least new data about biodegradation and or mechanical properties.
Author Response
Dear Editor,
First of all, thank you very much for giving us the possibility to revise and ameliorate our paper.
Please, find enclosed the revised version of the manuscript, as well as our response to the Reviewer's comments.
As required, we have addressed the points raised by the Reviewers and have completed the revision process. Accordingly, we are resubmitting a new version to go back to the Reviewers for re-evaluation.
Once again thanks a lot for your kind attention and assistance.
We do hope the revised manuscript will definitively meet the criteria for publication in Applied Sciences Journal.
Best regards,
Michelina Catauro,
Corresponding author
Reviewer 2
The manuscript requires strong improvements both in terms of presentation of scientific data and in terms of novelty of the work. Moreover, it requires extensive editing of writing style and English language. Please, provide at least new data about biodegradation and or mechanical properties.
The authors thank the reviewer for his/her valuable suggestion. However, they feel that they lacked in clarity in stating the purpose of this work. In fact, it aimed to characterize microstructurally the polycaprolactone/SiO2 and polycaprolactone/TiO2 hybrid materials obtained via sol-gel route and to assess their bioactivity in vitro. Furthermore, in the consciousness that the oxides under study are able to bond to the living bone, but an implant could fail as a consequence of microbial infections, antimicrobial capability of the synthetized hybrids was preliminarily investigated in vitro vs. Escherichia coli.
The authors are aware of the importance of investigating mechanical properties, and some analyses have been already carried out, but they do not fall in the manuscript scope. Indeed, they are going to be considered in another paper (still in progress), in which comparisons among several biomaterials will be deeply described and rationalized.
As regards the present manuscript, many efforts have been taken to improve it and to make it suitable for publication, as follows. The aim of the work in the introduction section has been clarified. The presentation of scientific data has been changed in some parts, e.g. concerning FT-IR characterization of the synthetized materials and SEM analysis, and the authors hope that in the present form the soundness of the results has been enhanced. Some literature references have been added, to support the discussion. The quality of figures has been enhanced, when needed. Finally, an extensive editing of the text has been carried out and several typos were corrected, some sentences were re-phrased to improve writing style and English language.
Reviewer 3 Report
This manuscript deals with the preparation via sol-gel method and spectroscopic characterization of silica/polycaprolactone and titania/polycaprolactone organic/inorganic composites. The introduction is a well representative framework of the state of the art but probably could be improved in some points. This is specific manuscript [2], probably in this regards it could be better to make reference with some review [IJ Zvonkina, MD Soucek, Current Opinion in Chemical Engineering, 2016, 11, 123-127, RB Figueira, CJR Silva, EV Petra, Journal of Coatings Technology and Research, 2015, 12, 1-35].
The paragraph 3 especially related to FT-IR analysis should be better correlated and this correlation should be well explained due to numerous shortcomings:
In line 136-143 I found sentence: “The reaction 4 shows the formation of hydrogen bond between the ester C=O group of the organic polymer, which acts as an H-acceptor, and the O-H group of the inorganic matrix. Hydrogen bonds establishment was proved by FT-IR measurements, whose spectra are reported in Figure 2.” The authors do not indicate the presence of hydrogen bonds in the tested systems in Figure 2. Broad absorption band in the range 4000-3000 cm-1 prevents the analysis of hydrogen bonds.
The authors wrote (line 145-146): “In SiO2/PCL6%wt spectrum (Fig. 2b), the band at 1720 cm-1 is attributed to the symmetric stretching of -CH2- of polycaprolactone”. I can not agree with authors. The absorption bands occurring in the range 1800-1600 cm-1 are related to presence of C=O bonds in different group.
The authors wrote (line 159-160): “In Fig. 3(c) the absorption peak may be described as the TiO6 octahedra vibration with different ligand kinds”. This statement is not clear. I suggest clarifying which absorption band is important. In the Figure 3 b there is no evidence of presence of PCL.
According to the authors (line 178-179) “SEM micrographs of TiO2 gel and TiO2/PCL gel samples, reported in Figure 5, did not evidence appreciable difference between the morphology of the two amorphous materials.” I cannot agree with authors the Figure 5 clearly show difference in the morphological properties of obtained composites.
I also suggest improve of quality in Figure 7.
The week point of the manuscript is the English that must be improved, in the attached pdf I highlighted various mistakes and typos that need to be corrected.
Comments for author File: 
Comments.pdf
Author Response
Dear Editor,
First of all, thank you very much for giving us the possibility to revise and ameliorate our paper.
Please, find enclosed the revised version of the manuscript, as well as our response to the Reviewer's comments.
As required, we have addressed the points raised by the Reviewers and have completed the revision process. Accordingly, we are resubmitting a new version to go back to the Reviewers for re-evaluation.
Once again thanks a lot for your kind attention and assistance.
We do hope the revised manuscript will definitively meet the criteria for publication in Applied Sciences Journal.
Best regards,
Michelina Catauro,
Corresponding author
Reviewer 3
This manuscript deals with the preparation via sol-gel method and spectroscopic characterization of silica/polycaprolactone and titania/polycaprolactone organic/inorganic composites. The introduction is a well representative framework of the state of the art but probably could be improved in some points. This is specific manuscript [2], probably in this regards it could be better to make reference with some review [IJ Zvonkina, MD Soucek, Current Opinion in Chemical Engineering, 2016, 11, 123-127, RB Figueira, CJR Silva, EV Petra, Journal of Coatings Technology and Research, 2015, 12, 1-35].
As suggested, the papers have been included as valuable references in the introduction section and in the reference list. Accordingly, all the references’ numbers have been changed.
The paragraph 3 especially related to FT-IR analysis should be better correlated and this correlation should be well explained due to numerous shortcomings:
The authors thank the reviewer, who gave them the opportunity to reconsider carefully some statements in the manuscript and to improve the discussion of their results. Thus, the responses are provided below after each constructive criticism.
In line 136-143 I found sentence: “The reaction 4 shows the formation of hydrogen bond between the ester C=O group of the organic polymer, which acts as an H-acceptor, and the O-H group of the inorganic matrix. Hydrogen bonds establishment was proved by FT-IR measurements, whose spectra are reported in Figure 2.” The authors do not indicate the presence of hydrogen bonds in the tested systems in Figure 2. Broad absorption band in the range 4000-3000 cm-1 prevents the analysis of hydrogen bonds.
The authors wrote (line 145-146): “In SiO2/PCL6%wt spectrum (Fig. 2b), the band at 1720 cm-1 is attributed to the symmetric stretching of -CH2- of polycaprolactone”. I can not agree with authors. The absorption bands occurring in the range 1800-1600 cm-1 are related to presence of C=O bonds in different group.
The authors apologize for their lack of clarity. Taking into consideration the reviewer’s comments, the description of FT-IR spectra of Fig. 2 has been changed, referring to previous published papers in order to support the chemical characterization. In particular, the authors agree with the reviewer about the signal at 1720 cm-1 and are sorry for the mistake. Thus, following the constructive criticism, the sentence has been completely changed and better correlated to previous discussion.
The authors wrote (line 159-160): “In Fig. 3(c) the absorption peak may be described as the TiO6 octahedra vibration with different ligand kinds”. This statement is not clear. I suggest clarifying which absorption band is important. In the Figure 3 b there is no evidence of presence of PCL.
The authors apologize for the misunderstanding and modified the manuscript in order to enhance the clarity. According to the reviewer’s comment, the discussion of spectra depicted in Fig. 3 has been improved based on literature data, and the comparison among spectra of SiO2, TiO2 and hybrid material was highlighted.
According to the authors (line 178-179) “SEM micrographs of TiO2 gel and TiO2/PCL gel samples, reported in Figure 5, did not evidence appreciable difference between the morphology of the two amorphous materials.” I cannot agree with authors the Figure 5 clearly show difference in the morphological properties of obtained composites.
As suggested, the authors re-evaluated their comments to figure 5 and changed the text accordingly: “SEM micrographs of TiO2 gel and TiO2/PCL gel samples, reported in Figure 5, evidence a more homogenous morphology for the first one, as expected. With the introduction of the organic phase (Fig. 5b) the unstructured TiO2 gel presents a micrometric feature. None of the two morphology, though, indicate a regular geometric morphology indicating crystalline structures or phase separation.”
I also suggest improve of quality in Figure 7.
As suggested, the figure has been changed in order to improve its quality. Moreover, the authors realized that also Fig. 2 had a poor quality. Thus, this figure was changed, too.
The week point of the manuscript is the English that must be improved, in the attached pdf I highlighted various mistakes and typos that need to be corrected.
All the mistakes and typos highlighted in the attached pdf file have been corrected.
The authors thank again the reviewer for his/her valuable suggestions and comments and hope that their manuscript will be taken into consideration for publication in the present form.
Reviewer 4 Report
In this manuscript, the authors present the synthesis and spectroscopic characterization of Silica/polycaprolactone and Titania/polycaprolactone hybrid inorganic/organic composites. Furthermore, they assessed the antimicrobial behavior of the synthetized hybrids against Escherichia coli bacteria. The manuscript was well written, despite can be improved by adjusting a series of typos and some missing information (highlighted in the attached .pdf). The experimental section was carried out in a rigorous way and the results interesting and worthy of publication. The manuscript can be accepted after a minor revision.
Comments for author File: Comments.pdf
Author Response
Dear Editor,
First of all, thank you very much for giving us the possibility to revise and ameliorate our paper.
Please, find enclosed the revised version of the manuscript, as well as our response to the Reviewer's comments.
As required, we have addressed the points raised by the Reviewers and have completed the revision process. Accordingly, we are resubmitting a new version to go back to the Reviewers for re-evaluation.
Once again thanks a lot for your kind attention and assistance.
We do hope the revised manuscript will definitively meet the criteria for publication in Applied Sciences Journal.
Best regards,
Michelina Catauro,
Corresponding author
Reviewer 4
In this manuscript, the authors present the synthesis and spectroscopic characterization of Silica/polycaprolactone and Titania/polycaprolactone hybrid inorganic/organic composites. Furthermore, they assessed the antimicrobial behavior of the synthetized hybrids against Escherichia coli bacteria. The manuscript was well written, despite can be improved by adjusting a series of typos and some missing information (highlighted in the attached .pdf). The experimental section was carried out in a rigorous way and the results interesting and worthy of publication. The manuscript can be accepted after a minor revision.
The authors thank the reviewer for his/her positive comments and for the opportunity to improve their manuscript, according to his/her suggestions. Thus, all the modifications required in the attached .pdf file were taken into consideration and the text was changed accordingly.
Round 2
Reviewer 2 Report
I am disappointed that authors did not answered in a detailed way to my questions. They claimed that they have reported substantially changes highlighted in yellow in the manuscript. But especially in the first part of the manuscript they have highlighted the same sentences already present in the first version of the manuscript. However, I have appreciated the improvement that they carried out in the discussion about IR.
Reviewer 3 Report
Thank you kindly for addressing the comments as indicated. The article may proceed.
