Environmentally Friendly Water-Based Self-Crosslinking Acrylate Dispersion Containing Magnesium Nanoparticles and Their Films Exhibiting Antimicrobial Properties
Round 1
Reviewer 1 Report
The manuscript by Steinerova et al. describes e new latex binder used as paint film, investigating its physico-chemical and antimicrobial properties.
Due to the need to prevent microbial colonization of water-based paints, which are very useful for eliminating VOCs from common use, the goal of this work is very interesting and important.
I have a few points that need to be addressed before publication.
- line 35: please introduce the acronym VOC here, otherwise it is without explanation in line 39.
- Figure 2: is it a figure taken from a website? Please specify better.
A license is required to use any material published elsewhere. In addition, if you have the correct authorization, remove the caption inside the figure ("Figure 1 Values shown are colony forming units per ml") and add a more detailed caption of your Fig. 2 complete with adaptation from the correct source - Fig. 3: where does it come from? I'm not able to find its mention in the main text, so it is not contextualized. Furthermore, the caption states "bacteris, fungi and yeasts". Which kind of bacteria or fungi or yeasts are shown?
Moreover, "bacteris" is not correct. The correct plural of bacterium is bacteria. - Fig. 6: what does "bacterial activity of Magnesium nanoparticles" mean? Maybe you have to say antibacterial activity or bactericidal activity.
- Line 243: The authors state that each test was performed in triplicate and the final result was represented by the arithmetic mean. Please, add the standard deviation for each value you show in this manuscript.
- line 330-332: the citation of table 8 and 9 produces confusion. Table 8 refers to LM latex, table 9 to L0.
Then, cite the table 9 in line 330 (L0 latex (blank)) and remove the sentence "the results are presented in table 9".
Or cite both the table 8 and 9 at line 332, eliminating the citation of table 8 at 330. - line 332: the authors state that the the addition of a pigment or filler only slightly affects the antimicrobial efficiency of the system. In my opinioni, the data presented did not shown a slight effect, on the contrary there was a significant increment in the effect of LM on S. aureus for 5 additives out of 10 used. 4 to 10 for E. Coli. 100% effect on A. brasiliensis for 3 additives out of 10.
Not all additives had an important effect and not on all the microorganisms. But it would be better to discuss the results highlighting the variability between different compound and different microorganisms.
Author Response
Authors’ response to Decision Letter
The specific response to the Reviewer´s comments is as follows:
Reviewer 1
Dear reviewer,
We are grateful to your constructive comments on our manuscript. The specific response to your comments is as follows:
Point 1: line 35: please introduce the acronym VOC here, otherwise it is without explanation in line 39.
Response 1: The acronym VOC has been added.
Point 2: Figure 2: is it a figure taken from a website? Please specify better.
A license is required to use any material published elsewhere. In addition, if you have the correct authorization, remove the caption inside the figure ("Figure 1 Values shown are colony forming units per ml") and add a more detailed caption of your Fig. 2 complete with adaptation from the correct source
Response 2: According to your comment and the suggestion of the other reviewer, the image has been removed to supplementary material. Yes, the picture was taken from the Internet. The image was modified according to your note and the correct source has been added.
Point 3: Fig. 3: where does it come from? I'm not able to find its mention in the main text, so it is not contextualized. Furthermore, the caption states "bacteria, fungi and yeasts". Which kind of bacteria or fungi or yeasts are shown?
Moreover, "bacteris" is not correct. The correct plural of bacterium is bacteria.
Response 3: We are sorry, there was a text upload error and one full paragraph, that had already been written, has not been uploaded. The type of MOs was not specified. Sentences „ It should be mentioned here, however that the InCan test provides only quantitative information. The nature of present microbial species was not therefore detected.” have been added for a better understanding of the reader. The word bacteris has been changed to bacteria. Point 4: Fig. 6: what does "bacterial activity of Magnesium nanoparticles" mean? Maybe you have to say antibacterial activity or bactericidal activity. Response 4: “Bacterial activity” has been changed to “antibacterial activity”.
Point 5: The authors state that each test was performed in triplicate and the final result was represented by the arithmetic mean. Please, add the standard deviation for each value you show in this manuscript.
Response 5: Standard deviations were added for all results where possible. Unfortunately, for some testing, this was not possible due to subjective evaluation (flash corrosion) or the same results (Cross-cut test). For antimicrobial testing, the evaluation was subjected to an accuracy of 5% and the deviation was calculated from three values using the standard deviation. Point 6: line 330-332: the citation of table 8 and 9 produces confusion. Table 8 refers to LM latex, table 9 to L0.Then, cite the table 9 in line 330 (L0 latex (blank)) and remove the sentence "the results are presented in table 9".Or cite both the table 8 and 9 at line 332, eliminating the citation of table 8 at 330.
Response 6: As recommended, the tables were cited together on line 496 (newly tables 9 and 10). Point 7: line 332: the authors state that the the addition of a pigment or filler only slightly affects the antimicrobial efficiency of the system. In my opinioni, the data presented did not shown a slight effect, on the contrary there was a significant increment in the effect of LM on S. aureus for 5 additives out of 10 used. 4 to 10 for E. Coli. 100% effect on A. brasiliensis for 3 additives out of 10.Not all additives had an important effect and not on all the microorganisms. But it would be better to discuss the results highlighting the variability between different compound and different microorganisms. Response 7: Here the translation omitted one word – “amount”. The phrase “only slightly affects the antimicrobial efficiency of the system“ should have been translated: „The data show that the amount (w/w) of a pigment or filler added only slightly affects the antimicrobial efficiency of the system”. It is already fixed in the manuscript. Likewise, the 5 most successful additives have been highlighted in the revised version of the manuscript and the effects of the individual additives on specific MOs have been discuss more particularly according to your recommendation.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
In this report, a water-based polymeric acrylate dispersion containing magnesium oxide nanoparticles was developed and the protective properties of the films were assessed with emphasis on the biocidal effect imparted by the magnesium nanoparticles. The antimicrobial efficiency of the pigmented and potential commercial biocidal product savings were also studied. Although the authors performed some tests and presented corresponding results, there are some mistakes or inadequate expressions to be modified before further consideration.
Here are some remarks to this manuscript:
1. Please avoid using “whose” in the title.
2. The abstract should state briefly the purpose of the research, the principal results and major conclusions. I recommend rewriting the current Abstract.
3. Line 40: “As a drawback, however, water-based paints are subject to microbial colonisation, which is an effect that needs to be prevented.” The claimed issue here is the key background of this work. However, no relevant information or supporting references were included. If so, it is hard for the readership to understand the significance of this work.
4. Line 42: “Water-based acrylate dispersions (latexes) constitute a universal, high-quality and environmentally friendly option. Their synthesis has been brought to a high level” Any supporting references?
5. Line 44: why self-crosslinking can overcome the drawbacks of common water-based polymeric dispersions?
6. Figure 1 is not the original result of this study. Please delete it or move it to the Supplementary material.
7. Line 50: “The prevention of biofilm formation and bacterial adhesion on various materials is subject to research” Why?
8. Line 64 “because metal oxide nanoparticles show potential for reducing bacterial contamination and, at the same time, can exert a favourable effect on the structural properties of the paint film” References?
9. Line 75: “lower chemical resistance and flash corrosion,” Why water-based acrylate paints show such drawbacks?
10. “The monomer proportions were selected so that the glass transition temperature of the latex was around Tg = 10.” Please provide the evidence. And why chose the Tg = 10?
11. Line 135: What were the reaction temperature for the 1 and 2 phases?
12. Figure 2 is not the original result of this study. Please move it to the Supplementary material.
13. The authors repeated the hydroplasticisation in this work. So what is the hydroplasticisation in this self-crosslinking acrylate dispersion containing magnesium nanoparticles?
14. The quality of the SEM images is too poor to find the presence and distribution of the magnesium nanoparticles. High-quality image should be provided.
15. Figure 6: Please provide the photos of bacterial activity of Magnesium nanoparticles against E. coli, P. aeruginosa, P. chrysogenum, and A. brasiliensis.
16. For the antimicrobial study, statistical analysis should be added.
Author Response
Authors’ response to Decision Letter
The specific response to the Reviewer´s comments is as follows:
Reviewer 2
Dear reviewer,
We are grateful for your constructive comments on our manuscript. The specific response to your comments is as follows:
Point 1: Please avoid using “whose” in the title.
Response 1: Based on your comment, we changed the title to: Environmentally friendly water-based self-crosslinking acrylate dispersion containing magnesium nanoparticles and their films exhibiting antimicrobial properties.
Point 2: The abstract should state briefly the purpose of the research, the principal results and major conclusions. I recommend rewriting the current Abstract.
Response 2: We rewrote the abstract, where the principal results and conclusions were added.
Point 3: Line 40: “As a drawback, however, water-based paints are subject to microbial colonisation, which is an effect that needs to be prevented.” The claimed issue here is the key background of this work. However, no relevant information or supporting references were included. If so, it is hard for the readership to understand the significance of this work.
Response 3: We rewrote the text dealing with this issue to point it out to the reader as the key background of this work. We added relevant references as well.
Point 4: Line 42: “Water-based acrylate dispersions (latexes) constitute a universal, high-quality and environmentally friendly option. Their synthesis has been brought to a high level” Any supporting references?
Response 4: References were added as required.
Point 5: Line 44: why self-crosslinking can overcome the drawbacks of common water-based polymeric dispersions?
Response 5: We revised the text and rewrote the corresponding part related to crosslinking (being a general tool for improvement of properties of latex coatings) and eventual self-crosslinking (as the one of many crosslinking strategies). Besides, we changed the sentence: „The drawbacks of common water-based polymeric dispersions“ in “The drawbacks of common latex coatings”. We hope that this message will be clear in the revised version of our manuscript.
Point 6: Figure 1 is not the original result of this study. Please delete it or move it to the Supplementary material.
Response 6: As recommended, Figure 1 has been removed.
Point 7: Line 50: “The prevention of biofilm formation and bacterial adhesion on various materials is subject to research” Why?
Response 7: We rewrote the text to justify the statement and we also added a relevant reference.
Point 8: Line 64 “because metal oxide nanoparticles show potential for reducing bacterial contamination and, at the same time, can exert a favourable effect on the structural properties of the paint film” References?
Response 8: References were added as required.
Point 9: Line 75: “lower chemical resistance and flash corrosion,” Why water-based acrylate paints show such drawbacks?
Response 9: We apologize for a confusing text and confusing terminology. Under the name „water-based acrylate paint“ we meant just „latex“. We also admit that the „lower chemical resistance“ was incomplete and fragmentary information. Therefore, we revised the text and rewrote this paragraph with the emphasis on flash corrosion in the case of the application of latex-based coatings. In order not to confuse the reader, the issue of chemical resistance has been removed, leaving only the topic of flash corrosion.
Point 10: “The monomer proportions were selected so that the glass transition temperature of the latex was around Tg = 10.” Please provide the evidence. And why chose the Tg = 10?
Response 10: We provided the explanation regarding Tg into the revised version: „ To provide well coalesced coatings on the one hand and non-tackiness of coating films on the other hand, the monomer proportions were selected so that the calculated glass transition temperature (Tg) of the latex polymer was around 10 °C. (Calculation was performed according to the Fox equation [46].) Based on your comment, we provided results of DSC measurements.
Point 11: Line 135: What were the reaction temperature for the 1 and 2 phases?
Response 11: The reaction temperatures were 85 °C for both phases. This information was given to the revised version of manuscript (Experimental section).
Point 12: Figure 2 is not the original result of this study. Please move it to the Supplementary material.
Response 12: Figure 2 has been moved to additional materials as recommended and has been replaced by a reference in the text.
Point 13: The authors repeated the hydroplasticisation in this work. So what is the hydroplasticisation in this self-crosslinking acrylate dispersion containing magnesium nanoparticles?
Response 13: The phenomenon of hydroplasticization was explained in more detail in the revised manuscript.
Point 14: The quality of the SEM images is too poor to find the presence and distribution of the magnesium nanoparticles. High-quality image should be provided.
Response 14: We tried to provide a better quality of SEM images, nevertheless, the presence and distribution of the magnesium nanoparticles is not still too much distinct. The possible reason of the poor quality of SEM images is a high level of nanoparticle dissolution, which was emphasized in the revised version of our paper.
Point 15: Figure 6: Please provide the photos of bacterial activity of Magnesium nanoparticles against E. coli, P. aeruginosa, P. chrysogenum, and A. brasiliensis.
Response 15: As required, Figure 6 has been replaced with an image showing efficacy against all the tested bacteria.
Point 16: For the antimicrobial study, statistical analysis should be added.
Response 16: Not only in the case of antimicrobial testing, standard deviations were added.
Author Response File: Author Response.pdf
Reviewer 3 Report
The manuscript presents interesting results. It suffers from:
- Introduction: authors should clearly review the advancement in the field and show the innovative aspect presented in this manuscript. I suggest to review: Crystals 2016, 6(10), 136; Colloids and Surfaces B: Biointerfaces 135 (2015) 1–7.
- The TEM imaging with EDS mapping are needed to illustrate the atomic distribution of the coatings.
- Viability tests Live/Dead are needed to clearly show the cells death at the interface of the coatings.
- XPS should be carried out to explain the oxydative states of the coating elements.
- A mechanism of microbial inactivation should be schematically presented.
- Authors should discuss the coating stability over time/cycles.
- Some typos slipped to the manuscript. I suggest you revise the whole text. As example: the word "Bacteries" does not exist.
Author Response
Authors’ response to Decision Letter
The specific response to the Reviewer´s comments is as follows:
Reviewer 3
Dear reviewer,
We are grateful to your constructive comments on our manuscript. The specific response to your comments is as follows:
Point 1: Introduction: authors should clearly review the advancement in the field and show the innovative aspect presented in this manuscript. I suggest to review: Crystals 2016, 6(10), 136; Colloids and Surfaces B: Biointerfaces 135 (2015) 1–7.
Response1: Thank you very much for very interesting articles. We have revised the Introduction part and incorporated these articles as sources into the new version of our manuscript so that the reader has an expanded idea of ​​a diverse and innovative application of metal oxide nanoparticles.
Point 2: The TEM imaging with EDS mapping are needed to illustrate the atomic distribution of the coatings.
Response 2: We apologize, we are unable to provide TEM with EDS mapping. This technique would certainly help to improve the quality of our research, but unfortunately, it is not available for us now. (We tried to perform SEM with EDS, but the size of magnesium particles was too low to detect and distinguish them visually by EDS mapping.)
Point 3: Viability tests Live/Dead are needed to clearly show the cells death at the interface of the coatings.
Response 3: We simulated the viability tests by means of the preparation and testing of imprints. The information is given in the experimental section (probably not clear enough), therefore we tried to clarify this issue and we added the explanation: “Firstly, the antimicrobial efficiency of the non-pigmented coating films was examined according to the extent of bacteria growth on coating sample surface (Table 7). …… To distinguish between bactericidal and bacteriostatic activity of the LM coatings, tests on imprints were further performed (Table 8)……. “
Point 4: XPS should be carried out to explain the oxydative states of the coating elements.
Response 4: We apologize again, but at the moment we do not have enough time to be able to make the XPS measurements. Nevertheless, we are grateful for your beneficial comment and we will implement XPS in our future research. We hope that our coming paper “Testing of new acrylic dispersions with MeO nanoparticles for use on anticorrosive and antimicrobial paints.” will contain the required information.
Point 5: A mechanism of microbial inactivation should be schematically presented.
Response 5: As required, the scheme of the mechanism of microbial inactivation by magnesium nanoparticles has been presented.
Point 6: Authors should discuss the coating stability over time/cycles.
Response 6: Unfortunately, we have not tested all the presented paint films for their time/cycle stability. At the moment we do not have enough time to be able to complete the tests. Nevertheless, we are going to focus on this issue in our next article (dealing with corrosion resistance of pigmented coatings with magnesium and zinc nanoparticles).
Point 7: Some typos slipped to the manuscript. I suggest you revise the whole text. As example: the word "Bacteries" does not exist.
Response 7: As recommended, the article was checked by a native speaker.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
The authors have addressed my concerns in the revision. In my opinion, the revised manuscript is acceptable for publication.
Reviewer 3 Report
Authors carried out the suggested improvements.
