Development of κ-Carrageenan Films Reinforced with Magnesium Oxide Nanoparticles for the Potential Treatment of Chronic Wounds: In Vitro and In Vivo Insights

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript by Rodríguez-Vicens et al. investigated the preparation of κ-carrageenan and polyethylene oxide composite films, further enhanced by the incorporation of MgO-NPs to improve their properties, exploring their potential application in the treatment of chronic wounds. Authors optimized the synthesis conditions of the films using a 2^k experimental design and systematically evaluated their mechanical properties, thermal stability, antibacterial activity, and biocompatibility. The experiment was well designed and meaningful. Some of the comments are as follows.

1. The introduction should focus on the advantages of MgO-NPs and their potential mechanisms in wound healing. The background of wound healing and microbial infections should be briefly described.
2. What is the basis for the amount of NPs added in κ-C-PEO films?
3. Why was the variable of MgO-NPs addition not considered in the design of the 2^k experiments?
4. In terms of antibacterial activity, DS-MgO-NPs did not seem to inhibit E. coli and P. aeruginosa, does it indicate that MgO-NPs is not suitable to be added to antibacterial materials.
5. Why were the Staphylococcus aureus, and Proteus mirabilis mentioned in the introduction not used as test microorganism?

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The work describes the preparation of films from carrageenan and PEO, optimization of the film composition for optimal thickness, swelling and strength, as well as characterization of magnesium oxide containing films, their antibacterial properties and compatibility with A.salina.

The motivation for adding magnesium oxide is not entirely clear considering the further suggested application of the films. The motivation should be more clearly stated in the introduction

The motivation for using A.salina for biocompatibility is not clear either; a cell toxicity experiment is required

Considering the poor antibacterial properties what are the next steps to improve them?

What is the mechanism of cross-linking of carrageenan with PEO and is it enough to obtain insoluble films? The paper does not provide any evidence of film insolubility. Even the swelling capacity is determined with 2 min exposure in a water media. However, it is not enough to establish equilibrium, most methods suggest 24 h.

It is more correct to choose PEO MW as an experimental factor rather than PEO type

How the authors explain the change in film strength depending on the composition, as well as thickness depending on the composition, this should be described in more details in the discussion section. It should also be noted that strength and thickness are related characteristics.

Author Response

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Reviewer 3 Report

Comments and Suggestions for Authors

As a reviewer, I have gone through the manuscript entitled “Development of κ-Carrageenan Films Reinforced with Magnesium Oxide Nanoparticles for the Potential Treatment of Chronic Wounds: in vitro and in vivo Insights”. The aim of this paper is to synthesize a polymeric films made by κ-carrageenan, polyethylene oxide, glycerin and magnesium oxide and to study a potential treatment of chronic wounds. This paper deals with a topic of major interest in medicine: wound healing. The main objective is focused on the mechanical features of the composite film (tensile strength, thickness, and swelling capacity). FTIR spectroscopy, thermal analyses (TGA and DTA), electronic microscopy (SEM), strains culture and antibacterial activity analysis and statistical analysis were also carried out. The concepts are clearly presented and can be easily understood by interested readers. There are some aspects that need to be clarified or corrected and these are given below:

• (1): In scheme 1, reverse the position of the oven and the refrigerator. You wrote in the summary (lines 128, 129) that drying occurs first and then cooling. It would be good to include the drying temperature and time (45 degrees C, 5 hours), as well as the cooling time (8 degrees C, 24 hours) in the diagram. This way the synthesis steps can be understood and reproduced more easily;
• (2): Examples from the literature with other similar composite used in wounds healing should be given for comparison and for highlighting the originality and quality of the composite presented in this work. From references 28 and 29 and similar ones, data on thermal degradation or mechanical analyses can be extracted with which a comparison can be made with the data obtained in this paper. These comparative data can be summarized in a table and presented at the end of the paper;
• (3): FTIR analysis was performed as transmittance in potassium bromide pellet or in reflectometry mode? What does resolution 16 mean? Usually the resolution of FTIR spectrometers is between 2 and 4 cm^-1. What kind of IR spectrometer did you use? Give the name of the device. Are there chemical interactions between κ-carrageenan, polyethylene oxide and glycerin due to the second step of the synthesis (magnetic stirring at 70° C)? This should be seen in the final composite (DS-MgO-NPs) by shifting some spectral bands to distances greater than the resolution of the IR spectrometer. κ-carrageenan, polyethylene oxide, glycerin and magnesium oxide do not affect living tissue (they are biocompatible). If chemical interactions occur between precursors and a new composite with new chemical bonds is obtained, then a biocompatibility study must also be performed. Consequently, the FTIR study should be further investigated.

Author Response

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Reviewer 4 Report

Comments and Suggestions for Authors

• Can the authors explain whether increasing the MgO-NP concentration or modifying the NP surface chemistry might yield better antibacterial outcomes?
• The authors are suggested to add EDS analysis to confirm the MgO-NP distribution and also ensure that they are not just aggregated but uniformly distributed.
• There are certain errors in the manuscript including grammatical and typological errors (For instance, figure 2 caption). It is suggested that the authors thoroughly proofread the manuscript to ensure that it is free of such errors.
• There are certain examples cited where κ-carrageenan composites exhibited antibacterial effects using other nanoparticles. Why do the authors believe MgO-NPs were ineffective in this case? Could factors like pH, film porosity, or nanoparticle surface reactivity be influencing this?
• It is mentioned that sample 4 was selected based on balance in tensile strength and swelling. However, was the contact angle measurements or other assessments of film wettability considered in this case, which could be relevant to wound dressing applications?

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

In my opinion the quality of the work has not been improved enough

If the films are soluble this creates inconvenience when using them as wound dressings
To providing evidence of insolubility is not a difficult experiment. Solubility can be checked quickly and easily, and it is not clear why the authors refuse to do this
It is also necessary to conduct the swelling experiment diferently keeping films in the medium for a longer period, at least 4 hours

Author Response

Thank you for your observation. The revised manuscript's supplementary materials include the solubility of films loaded with magnesium nanoparticles, as suggested. The corresponding methodology has also been added and supported with a new reference. Considering the Editor's comments, experiments about the swelling capacity of films loaded with magnesium nanoparticles have also been added in the supplementary material.

Reviewer 3 Report

Comments and Suggestions for Authors

Detailed answers were provided to all questions and necessary changes were made. I am satisfied with these answers and changes and have no further requests. The corrected paper has the scientific standing to be published in the journal.

Author Response

Thank you for your careful consideration and comments.

Round 3

Reviewer 2 Report

Comments and Suggestions for Authors

the authors have addressed all the comments, the manuscript can be published now