Antimicrobial Properties of Zinc Oxide Nanoparticles Synthesized from Lavandula pubescens Shoot Methanol Extract

Round 1

Reviewer 1 Report

The present study reported the antimicrobial activity of zinc oxide nanoparticles prepared us-ing Lavandula pubescens shoot methanol extract. The results showed that L. pubescens shoot extract loaded ZnO nanopar-ticles exhibited good antimicrobial activity against both bacteria (P. aeruginosa and S. au-reus) and fungi (A. niger and A. terrus). Loading ZnO oxide nanoparticles with the shoot extract enhanced its antimicrobial activity, with higher ZI, and lower MIC, and MBC/MFC. The prepared ZnO nanopar-ticles are a promising alternative for treating a wide array of microbes due to their ad-vantages in preventing microbial growth. The topic as such is interesting and suitable for the journal, but some issues need to be further addressed.

1. Does the cytotoxicity of ZnO have any effect on normal cells of animals or humans, except for bacteria and fungi?

2. What is the dispersibility of the synthesized ZnO and is there any quantitative index?

3. The photocatalytic property of ZnO is mentioned in the paper, does this property correlate with its bacteriostatic property? Does the specific wavelength of light contribute to its bacterial inhibition effect?

4. The inhibition activity of ZnO NPs is inversely proportional to their size, and the particle width is increased with the increase of LPME modification concentration, does it affect the inhibition activity of ZnO NPs itself? And does the modification cover the sites of Zn2+ release from ZnO NPs and weaken the bacteriostatic activity of the nanoparticles themselves?

5. How was the amount of ZnO NPs and the two drugs determined in the experiment to assess the bacteriostatic activity, which was different?

6. In what form was the LPME bound to ZnO, was it physically adsorbed or did it form some chemical bond?

7. Is it possible that the modification directly in the alkaline solution of synthetic ZnO NPs may destroy some bioactive substances in LPME?

8. Are the modifiers strongly bound to the ZnO NPs? Can they be stored stably in solution or in air for a long time?

9. Is there an optimal concentration of LP-ZnO-NPs for bacterial inhibition when only two concentrations of LP-ZnO-NPs are used in the experiment?

Author Response

Hello dears

I have made the revision using the track change, addressing your comments. Additionally, Responses to comments were made point by point.

Author Response File: Author Response.docx

Reviewer 2 Report

Overall it's an interesting and useful topic, the experimental approach is sound and the data supported the improved antimicrobial activity of ZnO nanoparticles loaded Lavandula pubescens shoot methanol extract. The following is some minor error need to be correct.

1.  The format of reference 37, 28 need to be the same as the rest of references.

2. In 3.1, “Diethyl Phthalate is a tetragonic agent “ètypo, should be teratogenic

3. In 3.2, paragraph 2:” which indicates the a rod-shaped ZnO crystal structure” è delete “the”

4.  On page 8,  Please delete “3. The antimicrobial activity of ZnO nanoparticles loaded with the methanol extract of L. pubescens shoots”. It’s a repetition of the 3.3 title on the next page.

5. The resolution of table 2~4 is bad, please fix it.

6. Fix the caption of Figure 5. Can’t see the last sentence.

 

Author Response

Hello dear

I have responded to the comments in red, addressing all raised comments. I have mentioned the changes made using the track change.

Author Response File: Author Response.docx

Reviewer 3 Report

The paper lacks the correct MDPI format to highlight where are the sections that must be changed (there are no numbers in the lines)

Introduction

The first idea of the second paragraph in the introduction section seems off 

" It is quite interesting to employ nanoparticles made of metals and their oxides. Due to their remarkable chemical and physical properties, high surface area to-volume ratio, and extraordinary antibacterial action, nanosized inorganic compounds have been studied. "

In the introduction section, in paragraph 3, the authors write "according to reports". Which reports?, only reference 2?

Even when the authors claim that ZnO is the most studied oxide, 19 references are too low. please add more references.

Materials and methods

Results

Seems enough to understand the paper

Page 9. the title of section 3.3. is duplicated

The following sentence makes no sense at all "The study's findings revealed that the examined bacteria and fungi behaved differently in terms of growth depending on the microbe type, antimicrobial substance properties, and solvent type." please adjust it.

Why tables 2-4 are images? Please transform those into actual tables according to MDPI guidelines

Figures 2 and 3 must be changed. Also, the headings of those figures do not comply with the MDPI format

Figure 5 is out-of-sight. it must be cropped to fit the page

For 2022, Applied Sciences uses separate sections for results and discussion. Authors must comply with MDPI guidelines

 

 

 

Author Response

Hello dear

I have addressed all the raised comments point by point in the attached letter. Track changes are used to highlight these addresses. I have separated the results from the discussion, following the mdpi format.

Author Response File: Author Response.docx

Reviewer 4 Report

The manuscript is written well but a few corrections have been required as per marked in the PDF. 

Comments for author File: Comments.pdf

Author Response

Hello dear

I have addressed the whole raised comments in the original manuscript using the track change icon.

Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

The authors have made the required modifications to the document