The Synergic Effect of Erythrosine and Gold Nanoparticles in Photodynamic Inactivation
Round 1
Reviewer 1 Report
In this manuscript, the authors studied the synergic effect between erythrosine and gold nanoparticles in photodynamic inactivation. The authors demonstrated that by adding Au NPs, the inactivation effect from erythrosine can be improved. Larger Au NPs give better inactivation results. Besides, the mechanism of the inactivation caused by erythrosine was also studied. This study provides a potential way to enhance the antibacterial effect using erythrosine at low risk to human health.
The manuscript can be accepted after revision.
1. The introduction section needs more references:
Line 32 – 37: The content needs references.
Line 64 – 70: Needs references.
Line 83 – 85: Needs references.
Line 87 “Moreover, it has an excellent antibacterial effect and is harmless to humans.”: Needs references.
2. Line 105 – 106 "...wavelengths not absorbed by erythrosine...": What does this sentence mean? In the experiment, the authors used 525 nm light which can be absorbed by erythrosine.
3. Line 154: How many AuNPs were used for each experiment? Although the volume of 20 uL was mentioned, it is not clear about the concentration of Au NPs in the solution.
4. Line 286 – 294: Previous literature (https://doi.org/10.1016/j.watres.2022.118125.) showed that the main functional species generated by erythrosine under visible light are 1O2 and O2-radicals. This should be discussed and cited.
Author Response
Dear reviewer,
Please see the attachment.
Best regards,
Shih-Chen Shi
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The paper provides a powerful antimicrobial approach that can selectively kill microbial cells called photodynamic Inactivation and its synergic effect of food coloring agent erythrosine and gold nanoparticles. The paper is well written and has clinical applications.
I suggest the following major revisions before considering this manuscript again for publication.
Please find below my comments:
- In the entire manuscript, the microorganism's scientific name is not mentioned in italics and needs correction.
- Gold nanoparticles are known for their excellent antimicrobial activity. But in the present manuscript, AuNPs do not show antimicrobial activity in the absence of photosensitization and irradiation effects, justify.
- The authors are suggested to add characterization methods such as XRD, SEM, and TEM and an explanation in the result section to prove the synthesis of gold nanoparticles of specific size.
- Synergic effect of erythrosine and gold nanoparticles with the mechanism of action is not clear. Reframe the entire section with proper cross-citations.
- The manuscript should be checked thoroughly for grammatical mistakes.
Author Response
Dear reviewer,
Please see the attachment.
Best regards,
Shih-Chen Shi
Author Response File: Author Response.pdf
Reviewer 3 Report
In this experiment, gold nanoparticles were used as the carrier and erythrosine as the photosensitizer to verify the sterilization principle of PDI. The topic was interesting, but there were some problems that need to be resolved. I would agree this paper to be published in Sustainability after major revisions. Following are the comments:
1. “Au NPs of four different sizes (10, 20, 30, and 40 nm) synthesized via chemical reduction were used”, the preparation process was not given, and the exact size of four Au NPs were not determined or not given. Please give solid proof.
2. Why did the authors use different sizes of Au NPs? The experiment results were not described in abstract or conclusion.
3. It is suggested to determine bacterial survival without the light irradiation or erythrosine.
4. How to determine the concentrations of ascorbic acid, mannitol, and sodium azide? Why was 10mM chosen as the scavenger?
5. The group corresponding to the blue line in Figure 2 did not show significant changes in bacterial mortality during 120s of green light exposure. Why?
6. Why are dead bacteria present in the blank control group in Figure 3?
7. Some references are out of date, so it is recommended that you choose the latest ones as your references.
Author Response
Dear reviewer,
Please see the attachment.
Best regards,
Shih-Chen Shi
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Manuscript ID: sustainability-2176929 (Revised Version)
"The synergic effect of erythrosine and gold nanoparticles in photodynamic inactivation"
The paper has been substantially revised and corrected. But, still following minor revisions are required before considering this manuscript for publication.
Please find below my comments:
- In the beginning of the results and discussion section, the size of the gold nanoparticles mentioned is 11 nm, 20 nm, 29 nm, and 40 nm. Whereas in the entire manuscript, AuNPs size is 10 nm, 20 nm, 30nm, and 40 nm. Please specify the correct results.
- If gold nanoparticles act as only carrier, then how come there will be a synergic effect. Justify
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
I am glad to see that the authors have made careful revisions according to my comments, and after reviewing this revised manuscript, I recommend the manuscript to be published in Sustainability.
Author Response
We are very thankful for the referee for the valuable comment.
