Charge-Modulated Synthesis of Highly Stable Iron Oxide Nanoparticles for In Vitro and In Vivo Toxicity Evaluation

Round 1

Reviewer 1 Report

In this manuscript by Woo et al, the authors synthesized three differently charged polymers (negative, neutral, and positive charges). The polymers were utilized to functionalize iron oxide nanoparticles (IONPs). In vitro and in vivo biocompatibility of as-prepared IONPs were tested, and no significant toxicity was observed. The manuscript provides a systematic comparison of differently charged IONPs, and the experimental design fully supports the results. I would like to see the publication of the manuscript after the following questions are addressed

1. In Figure 3c, there seems to be aggregation in the negatively charged INOPs from the DLS data. The authors should discuss that in the manuscript.
2. In section 3.3, the authors tested stability of the IONPs in water and cell culture medium at 4 degrees. Stability under other conditions should also be included. For example, stability at 37 degrees and in FBS should be provided.
3. In Figure 5a, cell viability of the positively charged IONPs is lower than the other two groups at 500 µg Fe/mL. Is this difference statistically significant?
4. There’s a typo in Figure 5a. In the last figure (SH-SY5Y), the blue bars should be positively charged.
5. Some histology images should be provided in the Supporting Information in addition to the summary in Table 3.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

Referee report on manuscript “Charge-Modulated Synthesis of Highly Stable Iron Oxide Nanoparticles for In Vitro and In Vivo Toxicity Evaluation“ by Sunyoung Woo et al.

The authors report the synthesis and characterization of iron oxide nanoparticles (IONPs) and how they play a critical role in the interaction between nanoparticles and biological components.

This is a rather interesting topic, which, of course, is needed in the development and promotion, the results that are obtained are interesting and can be accepted for publication after a more detailed disclosure of some ambiguities and uncertainties.

Line 35. Introduction.  References [1-6], about IONP, showing the relevance of the work are already quite old (2011, 2011, 2011, 2011, 2012, 2012). It is important to show that in recent years, the interest to IONP research continues to grow. See, for example, recent MDPI open access papers:

Serga, V.; Burve, R.; Maiorov, M.; Krumina, A.; Skaudžius, R.; Zarkov, A.; Kareiva, A.; Popov, A.I. Impact of Gadolinium on the Structure and Magnetic Properties of Nanocrystalline Powders of Iron Oxides Produced by the Extraction-Pyrolytic Method. Materials 2020, 13, 4147. https://0-doi-org.brum.beds.ac.uk/10.3390/ma13184147

Kahil, H.; Faramawy, A.; El-Sayed, H.; Abdel-Sattar, A. Magnetic Properties and SAR for Gadolinium-Doped Iron Oxide Nanoparticles Prepared by Hydrothermal Method. Crystals 2021, 11, 1153. https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11101153

Qiao, J.; Wang, T.; Zheng, K.; Zhou, E.; Shen, C.; Jia, A.; Zhang, Q. Magnetically Reusable Fe₃O₄@NC@Pt Catalyst for Selective Reduction of Nitroarenes. Catalysts 2021, 11, 1219. https://0-doi-org.brum.beds.ac.uk/10.3390/catal11101219

Line 49. The end of the sentence needs supporting reference.

Line 59. The end of the sentence probably also needs supporting reference.

Line 131. Did you observe any sample aging during TEM measurements?

Fig.2 (a). please indicate the error bar for the degree of polymers.

Fig.3 (c ) the horizontal axis can start from 1 nm.

Fig.3 (d) please also to how numbers, otherwise, the data from the middle of the figure is not visible and loses its meaning.

Fig. 4 (c and d). correct 0day --> 0 day

Author Response

Please see the attachment.

Author Response File: Author Response.pdf