Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The authors developed an aptamer-based concentration (not detection) system targeting environmental E. coli isolates for quick detection of E. coli to assure water safety.

Abstract: The former part is somewhat redundant. Could you condensate it? Instead, please add the more results that you obtained in this study.

It is unclear whether the aptamer that you obtained can distinguish living E. coli from dead ones. if not, the conventional culture-based methods for E. coli detection may be better.

MNPs are costly. Please discuss expense among this and the similar methods.

Line264：You mentioned "The mixture was incubated at 4°C for 15 minutes." Please indicate the purpose of it.

Line269-270：The bacteria names are written in italics.

Line272：Five-minutes may be too short to bind aptamer to target. Discuss it by comparing the previous studies.

It is noteworthy that the authors have not yet developed an aptasensor utilizing an electrochemical or photochemical reaction. Your continued reliance on the culture method indicates that the issue they aimed to address in this work remains unresolved.

Author Response

The responses to reviewer 1 are attached in PDF format.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The presented work is devoted to the urgent problem of developing fast methods for detecting E. coli in aqueous samples using aptamers conjugated with magnetic nanoparticles. The study has practical implications for monitoring water quality, especially in countries with limited resources. However, the work contains a number of significant drawbacks.

Despite this, there are a number of issues that are recommended for correction:

1. More than 50% of the articles used were published more than 5 years ago, it is necessary, if possible, to replace them with more recent and relevant ones;
2. Much attention is paid to the introductory part of the article and it takes 3 pages, therefore it is recommended to shorten the introductory part;
3. It is necessary to add a comparison of current methods for detecting E.coli with those used in the study;
4. Paragraph 3.3: if monitoring has been carried out several times, it is necessary to provide error bars for the data illustrated in Figure 3A;
5. Figure 6: it is necessary to provide a quantitative assessment of the demonstrated results in order to improve understanding of the final result of the study;
6. The characteristics of nanoparticles are completely absent: shape, size, and the presence of agglomerates. There is also no image of the resulting nanoparticles;
7. There is no description of the proposed mechanism of binding of aptamers to magnetic nanoparticles.

The presented work addresses an important issue and offers a potentially useful technical solution. However, the publication of this article requires drastic refinement and a significant improvement in the presentation of the results. In its current form, the work can be considered as a preliminary study requiring significant development.

Author Response

The responses to reviewer 2 are attached in PDF format.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

I have confirmed that all points that all reviewers pointed out to be revised were thoroughly revised by authors.

The present article is acceptable in its present form.

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have corrected all comments.