Green Synthesis of Anti-bacterial Nano Silver by Polysaccharide from Bletilla Striata
, Yuxin Tong, Mingyang Zen, Zhile Liang, Minghao Li *, Ran Yan * and Yue Wang *Round 1
Reviewer 1 Report
In the materials and methods section:
please write the preparation and the characterization section in detail for the researcher to use the conditions applied in your experiment.
why did you not detect MICs of the tested nanoparticles against the tested microorganisms
In Results:
authors need to present the antimicrobial results in detail for each organism
Author Response
- Please write the preparation and the characterization section in detail for the researcher to use the conditions applied in your experiment.
Response:
Thank you very much for your suggestion. More details of the experimental methods have been updated in the revised manuscript.
- Why did you not detect MICs of the tested nanoparticles against the tested microorganisms.
Response:
As you said, MICs is a useful test method to characterize the bacteriostatic effect. But, in this study, we wanted to compare the more daily use of 75% ethanol to the antibacterial effect of Ag NPs and Ag gel. For these three agents are not the same dosage forms, the minimum inhibitory concentration might not reflect the actual effective components concentration. Herein the antibacterial rate data were shown to prove the broad-spectrum fungicide of silver nanoparticles. In the revised version, the detailed results including test temperature and action time are presented.
- In Results: authors need to present the antimicrobial results in detail for each organism.
Response:
Further discussion has been added to the results.
Reviewer 2 Report
In this manuscript, the Authors reported the green synthesis of silver nanoparticles from Bletilla striata polysaccharide (BSP). Synthesized Ag NPs were characterized by UV, SEM, TEM, and DLS. Antibacterial activity was tested against both gram-positive and negative bacteria. Overall, the presentation is in good shape. However, it lacks some clarity to publish in a high-quality journal of "inorganics". There are some points to be settled as follows:
1. Introduction is very short, not covered all recently published articles. It needs broad applications with motivation. A review article regarding the green synthesis of Ag NP can be followed (https://doi.org/10.1016/j.cogsc.2018.06.007).
2. What are the roles of every reactant in the synthesis?
3. Why "carbomer" was used?
4. What is the source of BSP? Is there any characterization of BSP carried out other than UV?
5. Why ICP and SEM were used and what were the results? - completely missed in the manuscripts, this is misleading.
6. TEM showed a heterogeneous distribution of NPs. Figures 2c and 2d may be misleading and not correctly represent the data. I would suggest providing triplicate measurements.
7. I would suggest providing, if possible, XPS measurements of the synthesis steps which clearly showed the change of charge of silver/silver ions.
Author Response
Thank you for your comments concerning our manuscript. All comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our research.
- Introduction is very short, not covered all recently published articles. It needs broad applications with motivation. A review article regarding the green synthesis of Ag NP can be followed (https://doi.org/10.1016/j.cogsc.2018.06.007).
Response:
Thank you very much for your comments. We have updated the relevant references.
- What are the roles of every reactant in the synthesis.
Response:
BSP can be used as a natural reducing agent. Silver nitrate acts as a silver salt and provides silver ions. More details of the synthesis methods have been updated in the manuscript.
- Why "carbomer" was used?
Response:
Carbomer is one of the most excellent matrix materials to prepare the gel. As nano silver solution is difficult to adhere to the skin for a long time, considering the further wider application, nano silver was made into a gel for transdermal administration, so we wish to prepare its gel dosage form while keeping its antibacterial activities.
- What is the source of BSP? Is there any characterization of BSP carried out other than UV.
Response:
BSP was bought from Shanghai Yuanye Bio-Technology Co., Ltd without any further processing, and it was not characterized in the use process.
- Why ICP and SEM were used and what were the results? - completely missed in the manuscripts, this is misleading.
Response:
During the characterization process, the EDX analysis from picture of SEM showed that there was a layer of organic matter on the surface of silver nanoparticles (Fig 3), which was proved to be an adherent of Bletilla striata polysaccharide. Meanwhile, the Ag content of silver nanoparticles was tested by ICP, and then the content of Bletilla striata polysaccharide could be derived.
- TEM showed a heterogeneous distribution of NPs. Figures 2c and 2d may be misleading and not correctly represent the data. I would suggest providing triplicate measurements.
Response:
Yes. We completely agree with your opinion. The fact that the Ag NPs size and morphology synthesized by plant extract is difficult to control because the weak reducing power. It is mentioned also in Badri Bhattarai’s literature (Green synthesis of gold and silver nanoparticles: Challenges and opportunities). Since no additional shaping agent was added in the process of preparing nano silver, the morphology and particle size distribution of nano silver are quite different. This is a common problem, and we will make a further study later. Thanks a lot for your guidance.
- I would suggest providing, if possible, XPS measurements of the synthesis steps which clearly showed the change of charge of silver/silver ions.
Response:
That’s really a good idea to supplement the XPS measurements. We tried to contact some other universities and professional testing institutions, but for the serious COVID-19 epidemic situation, it is hard for us to get the XPS measurement in a short period of time required by the journal. Thank you for your understanding.
We appreciate for your warm work earnestly, and hope our correction will meet with approval.
Round 2
Reviewer 2 Report
I would suggest accepting it for publication.
