Surface-Enhanced Raman Scattering for Probe Detection via Gold Nanorods and AuNRs@SiO₂ Composites

The authors have investigated a self-assembly method that was used to prepare gold nanorod composites, which were applied to trace detection by evaluating their surface-enhanced Raman spectroscopy characteristics. Then the seed growth method was used to adjust the amount of AgNO₃ solution, enabling the preparation of gold nanorods with different aspect ratios. In my opinion, the subject of this manuscript is very interesting and applicable in industry. I recommend this article for publishing in the Coatings; however, it needs some major revisions:

Response：Thanks for your letter and the constructive comments on this article in your busy schedule. we sincerely thank the editors and all reviewers for their valuable feedback that we have used to improve the quality of our manuscript. In addition, all of us authors have carefully read the comments that you have given us, and have discussed and revised each of these issues. The reviewer comments are laid out below in normal font and specific questions have been numbered. Our responses are given in italicized font and changes/additions to the manuscript are given in the red text. Please find our response to the comments as detailed below:

Comments 1: Abstract was prepared well but please define the abbreviation of SERS, surfaceenhanced Raman spectroscopy, and TEOS. Moreover, indicate the originality of this work in the abstract.

Response 1: Thank you for pointing this out. I agree with this comment. Therefore, I explained SERS in the ninth line of the article and changed it to Surface Enhanced Raman Scattering (SERS). TEOS in line 18 is interpreted as tetraethyl orthosilicate (TEOS).

Comments 2: Have you studied the electronic properties of gold as the first-row transition metal and silicon with semiconducting characteristic? Please consider a paragraph about the crystal structure of these elements and their effects on your work with citation in the introduction.

Response 2: Thanks to your suggestion, gold nanostructures exhibit strong optical absorption and optical scattering properties due to local plasmon resonance. 33 lines have been added in the text.

We think silica in this paper is mainly reflected in its good stability. The adhesion of silicon layer makes the gold nanomaterial stable, and it is not easy to agglomerate the gold nanoparticles. The details are added in lines 59-63

Comments 3: Page 1, line 30, “…biosensors and imaging,[66-8]…” it seems [6-8] is correct.

Response 3: We appreciate reviewer’s suggestion.I have changed imaging[66-8] in line 31 of the first page to [6-8].

Comments 4: Page 1, lines 31-33: “Raman spectroscopy is not an ideal detection method, but the development of surface-enhanced Raman spectroscopy (SERS) techniques means that trace detection is possible”. It needs to represent the citation for convincing why Raman Spectroscopy is not the ideal detection method and what is the criterion of comparison of RS and SERS.

Response 4: I will follow your advice and add the following in lines 70-78: Raman spectrum is a kind of scattering spectrum, based on the Raman scattering effect, the information of molecular vibration and rotation is obtained, which is applied to the study of molecular structure. However, Raman spectroscopy requires a lot of energy, and fluorescence has a great interference with it. Surface-enhanced Raman scattering SERS enhanced by 104~106 orders of magnitude compared with Raman scattering effect: The relative shape and intensity of bands in SERS were different from those in common Raman. Many vibrational bands that do not exist in ordinary Raman spectra can be observed in SERS. Therefore, Raman spectroscopy is not ideal as a means of detection。

Comments 5: Page 2, lines 86, 87: “This work provides theoretical support for the use of precious metal nanoparticles as substrates for trace detection and daily application.” What do the authors mean from the theoretical support? Is there any applied theoretical software? Please describe it.

Response 5: Thank you for pointing this out. This sentence is not thoughtful, and we have changed it to: This work provides ideas and detection methods for trace detection and daily application of precious metal nanoparticles as a substrate.At the line of 104-106.

Comments 6: Line 68: …the SERS activity.[19]o …” Please delete the sign of o superscript of [19].

Response 6: Thank you for pointing this out, we have deleted the sentence after the superscript [19].

Comments 7: Line 155: “The peak at 1510 cm-1…” Please replace the cm-1 to cm^-1 .

Response 7: We will follow your advice and have replaced cm^-1 with cm-1 in line 195.

Comments 8: In Figure 3, it has been seen that the curve of AgNO3 1.25 ml is different with other curves. How do you illustrate it?

Response 8: Thanks for your attention, the curve drop may be due to energy instability during Raman testing and the beam burning through the sample.

Comments 9: Please modify the AuNRs@SiO₂ to AuNRs@SiO₂ in the whole manuscript. For example, lines 227 (caption of Figure 9), 229, …

Response 9: Thanks to the reviewer's suggestion, we have revised AuNRs@SiO2 into AuNRs@SiO₂ in the entire manuscript, and the specific positions are respectively in lines 165, 252, 268 and 270.

Comments 10: Please increase the quality of Figures 11, 12. Moreover, in the Figures, it is better use the non-bold type setting in the Figures or Tables including letters or numbers in the axes.

Response 10: Thanks for your comments, We have modified Figure 11,12 and improved the clarity.

Comments 11: I recommend the authors to have a concise conclusion section after discussion section to give the readers a summary of their work.

Response 11: Thanks for your suggestion, I have added the conclusion section to the paper, changing the discussion in Part 4 to the Conclusion, and the results in Part 3 to the Results and Discussion.

Comments 12: Please cite the references 15,18, 26, 27 in the text. Moreover, pay attention to their order in the text.

Response 12: We will follow your suggestion and have quoted references 15, 18, 26 and 27，update the reference.

4. Response to Comments on the Quality of English Language

Point 1:

Response 1:   

5. Additional clarifications

No