Magnetic Nylon 6 Nanocomposites for the Microextraction of Nucleic Acids from Biological Samples

Round 1

Reviewer 1 Report

The manuscript “Magnetic nylon 6 nanocomposites for the microextraction of nucleic acids from biological samples” by Chubarov et al. describes a magnetic extraction process for nucleic acids.

The manuscript is well written and states an original idea.

To my opinion a major revision is needed.

Please address the following issues:

The following sentence needs a description what actually high means (e.g. in US-$):

“Although many MNPs are commercially available, the NA kit cost is extremely high.”

The following sentence is misleading as I think you mean that the companies rarely present information but wrote that all of them have this rare information:

“The companies’ websites present only rare information about the specificity, capacity, and release efficiency”

Please explain in the following sentence what you mean by high magnetic properties (susceptibility, saturation magnetization, magnetization in distinct fields, etc.):

“Magnetite nanoparticles (Fe3O4) are the most perspectives for the nucleic acids’ isolation relying on their high magnetic properties.”

The following sentence is also misleading since you mean that the large specific surface area is suitable to capture a great amount of NA molecules but small nanoparticles have the tendencies to oxidize and aggregate. However, you indicate that the surface area leads to oxidation and aggregation which lead to low stability:

“The large surface area provides effective NA capture but leads to low stability upon oxidation and aggregation [7,8,19].“

What does the surface coating affect and which surface coating do you mean?

“The surface coating is required for better colloidal stability in aqueous media”

Please give references for the following sentence:

“Moreover, surface functionalization may provide adsorption of specific NAs.”

Figure 1 and Figure 2 show completely contradictory mechanisms. While figure 1 shows large nylon fibres decorated with magnetite nanoparticles, figure 2 indicates the formation of core-shell particles. I recommend to adapt figure 2 and show a different mechanism where the nanoparticles bind to nylon. For the function of the extraction, this does not matter but it matters for the storyline and the schematic description.

Figure 3:

I do not understand, why you show the whole NIR region? The interesting region is between 6300 and 3800 cm-1. Moreover, is it also possible to have a Mid-IR spectrum to verify the composite material. Mid-IR will also show you the magnetite particles and not only organic vibrations.

Figure 4: Same as for figure 2, you should adapt the geometries to the real geometries of your composite.

Figure 6: Please use a binding capacity which relates to either the surface, the immobilized nucleotides, or the mass of the used particles. The use of percentage does not help to compare your system with commercial systems. Even though it seems likely that you have a specific adsorption mechanism.

Table 3: here you should also use absolutes (in addition to percentages). It is not clear how you can release 88% of your target RNA while only capturing 60%.

Conclusion:

Can you emphasize the advantages of your magnetic particles for nucleic acid extraction? If possible use numbers to compare your particles with commercial solutions.

Author Response

The authors gratefully thank the Referee for the constructive comments and recommendations, which help to improve the readability and quality of the paper. All the comments are addressed accordingly and have been incorporated into the revised manuscript. Detailed responses to the comments and recommendations are as follows. Please note that all the comments are bold-faced, and the authors' reply follows immediately below the comments (see the file in attachment).

Author Response File: Author Response.pdf

Reviewer 2 Report

The article is well written, but still I have some concerns, for example:

- some english errors, see raw 35;

- a brief sentence in the methods for the Fe3O4 synthesis;

- why the authors choose the film deposition for FTIR? is quite an unclear spectrum; no visible modification; did the authors did quantitative measurements? 

- also, it is not clear if the proposed Fe3O4 composites can be used in real biological samples, after the lysis procedure to separate the NA?

- what was the logical thinking of the TEM, different scales, still not clear how the nanoparticles look like after the coverage; clear for the bare ones, as expected for coprecipitation method;

- for the ones with silica coverage look like? what was the point for this type of particles?  

- probably a better structure of the article would make it more clear;

- no XRD, no magnetization measurements, it is necessary in order to say it is magnetite; and to my understanding it is an already published method, but it is of the authors? 

Author Response

The authors gratefully thank the Referee for the constructive comments and recommendations, which help to improve the readability and quality of the paper. All the comments are addressed accordingly and have been incorporated into the revised manuscript. Detailed responses to the comments and recommendations are as follows. Please note that all the comments are bold-faced, and the authors' reply follows immediately below the comments (see the file in attachment).

Author Response File: Author Response.pdf

Reviewer 3 Report

This manuscript by Bulgakova et al reports using Magnetic nylon 6 nanocomposites for the microextraction of nucleic acids from biological samples. The experiments were well designed and the data can support their conclusion. The authors also provide detailed experimental procedures so that others can readily repeat their results. The author also provided in-depth insight into the findings from this study. Therefore, the reviewer recommends the manuscript for publication after minor revision.

1.     In Figure 3, the author may need to confirm whether the range of measurement (4000 – 12500 cm^-1) is correct since the range of typical FT-IR spectrum for functional group measurement is within 500- 4000 cm^-1.

2.    In Figure 6, the reviewer suggests to add all the original data points to this figure.

3.    In this manuscript, when the author mentioned “Magnetic nanoparticles (MNPs) have broad application prospects in various molecule loading and separation applications due to their unique properties”, the author may also need to cite the references which can further support this claim: Nanotheranostics, 2019, 3, 166-178; NMR in Biomedicine, 2013, 26, 1176-1185.

Author Response

The authors gratefully thank the Referee for the constructive comments and recommendations, which help to improve the readability and quality of the paper. All the comments are addressed accordingly and have been incorporated into the revised manuscript. Detailed responses to the comments and recommendations are as follows. Please note that all the comments are bold-faced, and the authors' reply follows immediately below the comments (see the file in attachment).

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The manuscript has been improved.