Amino Acid Selection Altered Silver Nanoparticles Morphology and Formation of Silver Oxide Layers

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The topic researched by the authors is a good attempt to increase the insight of silver nanoparticles and their amino acid-based synthesis routes. However, the following corrections and modifications need to be done in the manuscript for enhancing the overall quality of the article:

1. Line no 17-18: ‘effect of amino acids on the characteristics of the AgNPs showed its affect’. Kindly rephrase it. In its current form, the meaning is unclear.
2. Amino acids play a role in imparting biofouling properties to nanomaterials as well. Authors are advised to include this in the Introduction and cite the relevant article (https://doi.org/10.1016/j.matchemphys.2022.126937).
3. Line no. 69-70: Avoid using first-person words such as ‘we’ in the manuscript. Please look for similar words present at many places in the entire manuscript and rectify. Additionally, authors are advised to include this part in the ‘Acknowledgement’ section rather than in section 2.1.
4. The methods used to perform the antibacterial activity should be written as a separate section in detail rather than merging it with section 2.2.
5. Line no. 108: What are AgNSs?
6. Line no. 122-123: Be consistent with writing the ‘nm’. It is missing in some places.
7. Figure 1B: The axis titles are not in English.
8. Figure 2 and 8: The quality of XRD graph is not good. Please replace it with a high-quality image where X and Y axis are visible. Figure 3: The caption is not in English.
9. In the XRD results, d-spacing should be written in terms of ‘Å’ rather than ‘nm’. Additionally, while writing dimensions of the nanoparticles, use ‘×’ symbol rather than the letter ‘x or X’.
10. Antibacterial studies and Figure 10: Authors need to discuss following things: (a) mention how different nanoparticle samples were used in a single plate; (b) what was the control and how was it different from other numbered samples, since there is similarity between them as visible in all the plates; (c) the antibacterial activity of silver nitrate (sample 11) is well-known in literature, however, it did not show any activity in the current results. Kindly discuss this by comparing with previously published works.
11. English of the manuscript should be improved, and all grammatical mistakes or typos should be rectified.

Author Response

Dear Reviewer,

Thank you for reviewing the paper and appreciate the time you spent. We tried to do our best to assign all the mistakes. We also changed the title of the study based on Reviewers’ suggestions to emphasize the main findings in the paper.

 

Review 1:

The topic researched by the authors is a good attempt to increase the insight of silver nanoparticles and their amino acid-based synthesis routes. However, the following corrections and modifications need to be done in the manuscript for enhancing the overall quality of the article:

1. Line no 17-18: ‘effect of amino acids on the characteristics of the AgNPs showed its affect’. Kindly rephrase it. In its current form, the meaning is unclear.

Response 1: The section was corrected.

1. Amino acids play a role in imparting biofouling properties to nanomaterials as well. Authors are advised to include this in the Introduction and cite the relevant article (https://doi.org/10.1016/j.matchemphys.2022.126937).

Response 2: Thank you for your suggestions. I did not come across this article before. It is a valuable suggestion that gives further ideas in nanomaterial design, which can be used in the development of resistant antibacterial surfaces.

1. Line no. 69-70: Avoid using first-person words such as ‘we’ in the manuscript. Please look for similar words present at many places in the entire manuscript and rectify. Additionally, authors are advised to include this part in the ‘Acknowledgement’ section rather than in section 2.1.

Response 3: The section was corrected, and Acknowledgement part was added to the paper for amino acids donation.

1. The methods used to perform the antibacterial activity should be written as a separate section in detail rather than merging it with section 2.2.

Response 4: The section was now corrected as Section 2.3

1. Line no. 108: What are AgNSs?

Response 5: It is now corrected as AgNPs.

1. Line no. 122-123: Be consistent with writing the ‘nm’. It is missing in some places.

Response 6: The section was checked, and no missing was observed.

1. Figure 1B: The axis titles are not in English.

Response 7: The mistakes were corrected.

1. Figure 2 and 8: The quality of XRD graph is not good. Please replace it with a high-quality image where X and Y axis are visible. Figure 3: The caption is not in English.

Response 8: All the figures were replaced to increase the visibility. The captions were corrected.

1. In the XRD results, d-spacing should be written in terms of ‘Å’ rather than ‘nm’. Additionally, while writing dimensions of the nanoparticles, use ‘×’ symbol rather than the letter ‘x or X’.

Response 9: The mistakes were corrected.

1. Antibacterial studies and Figure 10: Authors need to discuss following things: (a) mention how different nanoparticle samples were used in a single plate; (b) what was the control and how was it different from other numbered samples, since there is similarity between them as visible in all the plates; (c) the antibacterial activity of silver nitrate (sample 11) is well-known in literature, however, it did not show any activity in the current results. Kindly discuss this by comparing with previously published works.

Response 10: The section was updated and further discussions were added.

1. English of the manuscript should be improved, and all grammatical mistakes or typos should be rectified.

Response 11: The language was checked, and mistakes were corrected.

Reviewer 2 Report

Comments and Suggestions for Authors

The authors demonstrated the strong influence of sugar ligand and different amino acids chemistry on the morphological and antibacterial activity of synthesized Ag NPs. The work proves advanced analysis of synthesized materials and thorough discussion of details. However, the title and body of work are slightly not consistent in the fact that there is a balance issue of material characterization vs. application (antibacterial effects); the former outweighs the latter. While the analysis of the HR-TEM is remarkable, it is important to reflect on the title and key message to pass onto reader. I recommend the publication of this work after a major revision amending the work following comments below:
1. There are several instances where the language is not English, e.g. axes titles in Fig. 1, Figure captions as in Fig. 3, and several more.
2. The HR-TEM and XRD sections is very large and involves many Figures. The best figure depicting useful information is Figure 9. It is readable. It is recommended to follow style of Fig. 9 to apply to rest of HR-TEM and XRD figures. From left to right, a compilation of (A) TEM image, (B-C) HR-TEM image, (D) FFT. Arrange a compilation of key! HR-TEM findings (you cannot add everything) and most importantly, make sure that everything is readable. 
3. The use of the maximum length and width dimensions allowed for graphics is recommended.
4. The XRD patterns are easier to compare if compiled in a single graphic. Patterns should be separated along the Y-axis with proper resolution to discern peaks from noise.
5. The diffraction signal at 31.44 2-theta cannot be real. If visualized properly, it may look real. 
6. It is recommended to find a relevant and strong descriptor for the Ag vs. AgO and the different crystalline phases of Ag. Sometimes the maximum intensity of phase a is compared to the maximum intensity of phase b. This should serve as credible alternative to Rietveld refinement. Percentage represetation of Ag vs. AgO and different phases will be a good thing to report in some Table.  
7. The use of Tables seems to be mandatory in this work provided the many parameters involved in material preparation, material characterization, and material application (concentration). I strongly recommend the use of table(s), to sum up key features from material synthesis, characterization, and antibacterial activity. The table cannot include the entire HR-TEM section. The table should be human-readable. 
8. HR-TEM images have problems in their scales; while the scale bar is thick and visible, the number itself is hard to read as well as the different lattice planes attributions. One lattice plane is sufficient to evidence in a HR-TEM image proving existence of Ag, AgO, phase a, or phase b. One lattice plane per each.
9. The sentence in line 244-245 is a problem. There is no need to measure all edges. Reader can read scale bar and can approximate. This applies to all reported cross sections. 
10. The word chunk is not proper. Aggregate or cluster is proper.
11. In line 217, 0.1008 nm is weird. three significant figures are to be used consistent with earlier spacing values, so the 0.1008 nm is to be 0.101 nm.
12. It is critical to report the sonication conditions that were applied (line 134-135). Equipment name and country of manufacturing, power applied, bath sonication or probe-sonication, if probe-sonication what kind of probe, total time on, pulse mode or else?, if cycles on/off then what time on what time off, etc., to help reader prove reproducibility. 
13. In line 88-89, it is recommended to add mention of service in acknowledgement, not in bulk of text.
14. In line 80, pure water is best to be replaced with deionized water or distilled water. This should be verified in lab.
15. In line 69-70, materials gifted are better mentioned in acknowledgement, not in bulk of text.
16. Use of subscripts where necessary.
17. The authors must correlate the synthesis conditions and the different observed morphologies. What is causing their emergence? They could for instance reinforce their discussing points in Fig. 5 by referring to the twinning model for nanoplatelet growth. Also, why are the platelets so perfect for LMA-Asn_AgNPs exclusively? Authors should discuss this in 2-3 sentences where appropriate.
18. In planned Table (above), maybe a comparison with garip studies (line 56) in same or another table is recommended, to show robustness and credibility of your own methodology.
19. Third digit is insignificant when analyzing HR-TEM data. Bracketed sentence in line 324 is to delete.
20. In planned table (above), it is important to use descriptors for material morphological (HR-TEM/SAED), chemical (UV-Vis), and antibacterical features.
21. List of abbreviations is too short. Consider adding HR-TEM, SAED, dsp (?), and many more.
22. Some figure captions are too short and lack proper description of different panel, e.g. Fig. 4 has no description of panels A, B, C, D, E, or F. For this reason is recommended to compile HR-TEM/SAED data in one graphic and to compile XRD data in another.
23. In said HR-TEM graphic, it is recommended to use A1, B1, C1, and D1 for first row to describe TEM image, HR-TEM image, zoomed HR-TEM image with possible inset, and SAED of LMA_AgNPs. For the second row, A2, B2, C2, and D2 for second row to describe TEM image, HR-TEM image, zoomed HR-TEM image with possible inset, and SAED of LMA_AgNPs.MA-Cys_AgNP, and so on.
24. Affect should be effect in line 18.

Author Response

Dear Reviewer,

Thank you for reviewing the paper and appreciate the time you spent. We tried to do our best to assign all the mistakes. We also changed the title of the study based on Reviewers’ suggestions to emphasize the main findings in the paper.

 

The authors demonstrated the strong influence of sugar ligand and different amino acids chemistry on the morphological and antibacterial activity of synthesized Ag NPs. The work proves advanced analysis of synthesized materials and thorough discussion of details. However, the title and body of work are slightly not consistent in the fact that there is a balance issue of material characterization vs. application (antibacterial effects); the former outweighs the latter. While the analysis of the HR-TEM is remarkable, it is important to reflect on the title and key message to pass onto reader. I recommend the publication of this work after a major revision amending the work following comments below:

 

 

1. 
   There are several instances where the language is not English, e.g. axes titles in Fig. 1, Figure captions as in Fig. 3, and several more.

Response 1: All the mistakes were corrected.
2. The HR-TEM and XRD sections is very large and involves many Figures. The best figure depicting useful information is Figure 9. It is readable. It is recommended to follow style of Fig. 9 to apply to rest of HR-TEM and XRD figures. From left to right, a compilation of (A) TEM image, (B-C) HR-TEM image, (D) FFT. Arrange a compilation of key! HR-TEM findings (you cannot add everything) and most importantly, make sure that everything is readable. 

Response 2: All the relevant Figures (1-9) were modified to enhance the readability.
3. The use of the maximum length and width dimensions allowed for graphics is recommended.

Response 3: All the Figures are in adaptable form. The resolution of the figures are now compatible with the journal’s suggestions.
4. The XRD patterns are easier to compare if compiled in a single graphic. Patterns should be separated along the Y-axis with proper resolution to discern peaks from noise.

Response 4: The XRD graphs are now adjusted, and the appearance of the peaks are now better. However, we are dependent on the central labs’ equipment quality and personal experience during the data collection.
5. The diffraction signal at 31.44 2-theta cannot be real. If visualized properly, it may look real. 

Response 5: We are aware that the data collection quality might not be ideal. However, still there is a bump even though it is slight. Since HRTEM gave the same hkl indices, we accept it as real.
6. It is recommended to find a relevant and strong descriptor for the Ag vs. AgO and the different crystalline phases of Ag. Sometimes the maximum intensity of phase a is compared to the maximum intensity of phase b. This should serve as credible alternative to Rietveld refinement. Percentage represetation of Ag vs. AgO and different phases will be a good thing to report in some Table.  

Response 6: Dear Reviewer, yes that would be good to have that. However, the SAED is focusing on a limited area. Unfortunately, we don’t have access to grazing XRD to produce quantitative data for the presence of Ag and AgO layers.
7. The use of Tables seems to be mandatory in this work provided the many parameters involved in material preparation, material characterization, and material application (concentration). I strongly recommend the use of table(s), to sum up key features from material synthesis, characterization, and antibacterial activity. The table cannot include the entire HR-TEM section. The table should be human-readable. 

Response 7: Table 1 is now included how amino acids contributed to the nanoparticles’ characteristics and antibacterial activity, where comparison with the literature is given as well.
8. HR-TEM images have problems in their scales; while the scale bar is thick and visible, the number itself is hard to read as well as the different lattice planes attributions. One lattice plane is sufficient to evidence in a HR-TEM image proving existence of Ag, AgO, phase a, or phase b. One lattice plane per each.

Response 8: The figures are now improved.
9. The sentence in line 244-245 is a problem. There is no need to measure all edges. Reader can read scale bar and can approximate. This applies to all reported cross sections. 

Response 9: The figures and writing were changed and are now readable now.
10. The word chunk is not proper. Aggregate or cluster is proper.

Response 10: The word chunk is now changed to aggregate
11. In line 217, 0.1008 nm is weird. three significant figures are to be used consistent with earlier spacing values, so the 0.1008 nm is to be 0.101 nm.

Response 11: nm is now converted into Angstrom, and significant digits are also corrected if needed.
12. It is critical to report the sonication conditions that were applied (line 134-135). Equipment name and country of manufacturing, power applied, bath sonication or probe-sonication, if probe-sonication what kind of probe, total time on, pulse mode or else?, if cycles on/off then what time on what time off, etc., to help reader prove reproducibility. 

Response 12: The sonication conditions are added.
13. In line 88-89, it is recommended to add mention of service in acknowledgement, not in bulk of text.

Response 13: The center’s name is now transferred to the acknowledgement section.
14. In line 80, pure water is best to be replaced with deionized water or distilled water. This should be verified in lab.

Response 14: Corrected.
15. In line 69-70, materials gifted are better mentioned in acknowledgement, not in bulk of text.

Response 15: That was moved to acknowledgement section.
16. Use of subscripts where necessary.

Response 16: All are now corrected.
17. The authors must correlate the synthesis conditions and the different observed morphologies. What is causing their emergence? They could for instance reinforce their discussing points in Fig. 5 by referring to the twinning model for nanoplatelet growth. Also, why are the platelets so perfect for LMA-Asn_AgNPs exclusively? Authors should discuss this in 2-3 sentences where appropriate.

Response 17: A discussion paragraph is now added.
18. In planned Table (above), maybe a comparison with garip studies (line 56) in same or another table is recommended, to show robustness and credibility of your own methodology.

Response 18: Table 1 is now included how amino acids contributed to the nanoparticles’ characteristics and antibacterial activity, where comparison with the literature is given as well.
19. Third digit is insignificant when analyzing HR-TEM data. Bracketed sentence in line 324 is to delete.

Response 19: The  3^rd digit is not deleted.
20. In planned table (above), it is important to use descriptors for material morphological (HR-TEM/SAED), chemical (UV-Vis), and antibacterical features.

Response 20: Table was designed as suggested.
21. List of abbreviations is too short. Consider adding HR-TEM, SAED, dsp (?), and many more.

Response 21: List of abbreviations was increased.
22. Some figure captions are too short and lack proper description of different panel, e.g. Fig. 4 has no description of panels A, B, C, D, E, or F. For this reason is recommended to compile HR-TEM/SAED data in one graphic and to compile XRD data in another.

Response 22: We omitted this to eliminate possible confessions.
23. In said HR-TEM graphic, it is recommended to use A1, B1, C1, and D1 for first row to describe TEM image, HR-TEM image, zoomed HR-TEM image with possible inset, and SAED of LMA_AgNPs. For the second row, A2, B2, C2, and D2 for second row to describe TEM image, HR-TEM image, zoomed HR-TEM image with possible inset, and SAED of LMA_AgNPs.MA-Cys_AgNP, and so on.

Response 23: The figures are replaced to increase the visibility.
24. Affect should be effect in line 18.

Response 24: Corrected.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have made the corrections as per the comments and the manuscript can now be accepted in its current form.

Reviewer 2 Report

Comments and Suggestions for Authors

Authors have significantly improved work as per comments. It is publishable in this form.