Review Reports - Green Methodology for Producing Bioactive Nanocomposites of Mesoporous Silica Support for Silver and Gold Nanoparticles Against <i>E. coli</i> and <i>S. aureus</i>

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

General Comments

This manuscript presents a green, one-pot synthesis of Ag@SBA-15, Au@SBA-15, and Au–Ag@SBA-15 nanocomposites using L-histidine as a biocompatible reducing and capping agent. The approach aligns with current research trends in environmentally friendly nanotechnology and antibacterial materials. The characterization is reasonably comprehensive, and the antibacterial performance against E. coli and S. aureus is clearly presented. The novelty resides in the low concentration of metallic nanoparticles (as low as 1 ppm) and their comparative evaluation within the SBA-15 framework. However, several scientific and structural weaknesses limit the manuscript’s impact and reproducibility. The mechanistic discussion is speculative and lacks direct experimental support. In addition, the manuscript does not include detailed statistical analysis, advanced material characterization (e.g., BET data for current samples), or comparison with state-of-the-art nanocomposite systems beyond a basic literature table. Hence, major revisions are necessary before this manuscript can be considered for publication.

Comments and Suggestions

#1 The authors claim novelty in the “green synthesis” using histidine and low metal concentrations. However, similar histidine-based reductions and SBA-15 supports have been reported. The claim of novelty must be better justified with more in-depth comparison to prior art using a broader and more current literature review.

#2 The BET surface area, pore size distribution, and porosity are cited from previous work. However, they must be re-evaluated for the nanocomposites themselves (after metal deposition) to assess changes in textural properties.

#3 The colloidal stability and surface charge (zeta potential) of nanocomposites are crucial for understanding their dispersion, interaction with bacterial membranes, and shelf life. These data are completely missing.

#4 While some mechanistic insights are provided (e.g., ROS generation, membrane disruption), no direct evidence is presented. The authors should consider adding DCFH-DA fluorescence assays, protein leakage assays, or electron microscopy of bacteria to support these claims.

#5 Antibacterial nanocomposites must maintain stability and not leach toxic metals over time. No data is provided on ion release kinetics, long-term performance, or shelf-life stability.

#6 The Au–Ag@SBA-15 phase is attributed to a galvanic replacement reaction, but no clear XPS or EDX mapping data are provided to confirm the alloy/core-shell architecture or spatial distribution of metals.

#7 FTIR analysis is superficial. Quantitative discussion (e.g., intensity ratios, shifts) should be added to confirm functionalization and metal binding. Additionally, solid-state NMR or XPS could reinforce FTIR claims.

#8 As the materials are proposed for biomedical and disinfection applications, at least a basic cytotoxicity assay (e.g., MTT on mammalian cells) or antioxidant assessment should be included to validate their biocompatibility.

#9 The significantly lower activity of Au@SBA-15 is acknowledged but not mechanistically explored. Gold is known for photothermal or catalytic effects—were any photothermal or light-activated tests conducted?

#10 The manuscript lacks critical discussion of cutting-edge nanocomposites using hybrid strategies (e.g., photothermal, photocatalytic, ROS-enhanced systems). Inclusion of more recent literature from 2022–2024 (e.g., ACS Applied Nano Materials, Biomaterials Science) would strengthen the state-of-the-art positioning.

#11 The antibacterial results lack standard deviation/error bars and statistical significance tests. These are essential to validate the reproducibility and confidence in the claimed microbial reduction rates.

#12 Please clarify which software tools were used for the analysis and indexing of the HRTEM and SAED images. Also, specify how the experimental patterns were calibrated and matched to standard crystallographic data (e.g., JCPDS files). This information is essential for verifying the accuracy and reproducibility of your structural characterizations.

Author Response

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Below are the comments for the authors to improve the manuscript:

Title clarity: The current title is confusing — the phrase "Supported Silver and Gold Nanoparticles 3 Against E. coli and S. aureus" is unclear. It should specify how the nanoparticles were synthesized or supported, and clearly indicate whether the study focuses on antibacterial or antivirulence activity.
Abstract details: Please include the minimum inhibitory concentration (MIC) values of the nanocomposites in the abstract.
Chemical details: Provide the CAS numbers and percentage purity for each chemical used in the study.
Size characterization: Clarify how the size observed in TEM images supports the particle size measured by DLS. The correlation between the two methods should be explained.
Zeta potential comparison: Are the zeta potential values the same for all nanocomposites? A comparative analysis is important to help explain the underlying antibacterial mechanism.
Data presentation: Tables 1 and 2 would be more informative and visually appealing if presented as bar graphs.
Figure 3 clarity: Figure 3 lacks meaningful interpretation. It should also include data for Au and Ag-Au samples to allow proper comparison.
Size discrepancy: In Figure 2, why is the particle size of Au-Ag@SBA-15 smaller than that of Au@SBA-15? Please provide an explanation.

Author Response

Journal: Technologies

Manuscript title: Green Methodology for Producing Bioactive Nanocomposites of Mesoporous Silica Support for Silver and Gold Nanoparticles Against E. coli and S. aureus

Names of authors: Una Stamenović, Dijana Mašojević, Maja Kokunešoski, Mojca Otoničar, Slađana Davidović, Srečo Škapin, Tanja Barudžija, Dejan Pjević, Tamara Minović Arsić, and Vesna Vodnik

Corresponding Authors: Una Stamenović and Vesna Vodnik

Type of manuscript: Research paper

Manuscript ID: technologies-3791367

Description of actions taken:

Italic – Reviewers’ comments

Green – Authors’ responses

RESPONSE TO REFEREES’ COMMENTS

We are thankful to the reviewers for their time, comments, and suggestions, which have certainly led to the improvement of the manuscript during the revision. We have carefully reviewed the comments and revised our manuscript accordingly.

We hope that the reviewers will find our responses to their comments satisfactory.

Reviewer 2:

Below are the comments for the authors to improve the manuscript:

Comment 1. Title clarity: The current title is confusing — the phrase "Supported Silver and Gold Nanoparticles Against E. coli and S. aureus" is unclear. It should specify how the nanoparticles were synthesized or supported, and clearly indicate whether the study focuses on antibacterial or antivirulence activity.

Response to comment 1. The title is rephrased from “Green Methodology for Producing Bioactive Nanocomposites of Mesoporous Silica Supported Silver and Gold Nanoparticles Against E. coli and S. aureus” to “Green Methodology for Producing Bioactive Nanocomposites of Mesoporous Silica Support for Silver and Gold Nanoparticles Against E. coli and S. aureus”.

- Our research is based on the investigation of antimicrobial efficiency against Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria, so the study focuses on the antibacterial activity of nanocomposites.

Comment 2. Abstract details: Please include the minimum inhibitory concentration (MIC) values of the nanocomposites in the abstract.

Response to comment 2. Minimum inhibitory concentrations for nanocomposites in question are already included in abstract in the following sentence: “Antibacterial evaluation toward Escherichia coli and Staphylococcus aureus showed that only Ag@SBA-15 at very low Ag concentration (1 ppm) during 2 h of contact, completely reduced growth (99.99%) of both strains, while the Au@SBA-15 nanocomposite requires higher concentrations (5 ppm) and time (4 h) to reduce 99.98% E. coli and 94.54% S. aureus”. One may say that the values of 1 and 5 ppm for Ag@SBA-15 and Au@SBA-15, respectively, could be considered as MIC of presented results. However, experiments for “real MIC” determination should be organized in a completely different way, and were not conducted in this research. Those values could be the same or smaller than the presented ones. For that reason, we can not exclusively claim that values of 1 and 5 ppm are MIC, and can’t be presented that way.

Comment 3. Chemical details: Provide the CAS numbers and percentage purity for each chemical used in the study.

Response to comment 2. According to the reviewer’s comment, CAS numbers and purity percentages of used chemicals are added to Section 2.1 Materials

Comment 3. Size characterization: Clarify how the size observed in TEM images supports the particle size measured by DLS. The correlation between the two methods should be explained.

Comment 4. Zeta potential comparison: Are the zeta potential values the same for all nanocomposites? A comparative analysis is important to help explain the underlying antibacterial mechanism.

Response to comment 3 and 4. The data considering zeta potential, i.e., nanocomposites’ surface charge, and accompanying explanations are now added to the Results and Discussion. The hydrodynamic particle size was not analyzed in this work and will be found in the next one.

Comment 5. Data presentation: Tables 1 and 2 would be more informative and visually appealing if presented as bar graphs.

Response to comment 5. Tables 1 and 2 have been amended and supplemented with significant differences between experimental data according to Tukey’s test (p < 0.05), and presented in Supplementary Material as Tables S2 and S3. Accordingly, new graphitic presentations of concentration-dependent reduction ability of the Ag@SBA-15, Au@SBA-15, and Au-Ag@SBA-15 on E. coli and S. aureus, over 2 and 4 h incubation time (Figure 9), as bar graphs with corresponding standard deviation bars are added.

Comment 6. Figure 3 clarity: Figure 3 lacks meaningful interpretation. It should also include data for Au and Ag-Au samples to allow proper comparison.

Response to comment 6. According to the reviewer’s comment, Figure 3 (now Figure 5) is expanded by FESEM images of Au@SBA-15 and Au-Ag@SBA-15 nanocomposites, together with corresponding EDX spectra for all three nanocomposites.

Comment 7. Size discrepancy: In Figure 2, why is the particle size of Au-Ag@SBA-15 smaller than that of Au@SBA-15? Please provide an explanation.

Response to comment 7. As the galvanic replacement reaction occurred during the synthesis of Au-Ag@SBA-15 nanocomposite, AgNPs were oxidized by HAuCl₄, followed by the reduction of Au³⁺ to Au⁰. This reaction occurs immediately and faster than the reduction of Au³⁺ by histidine. Consequently, the Au atoms grow on the Ag surface, resulting in the formation of Au-Ag alloy NPs, whose size is smaller than that of AuNPs obtained by the reduction of Au³⁺ with histidine alone.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The authors reports “Green Methodology for Producing Bioactive Nanocomposites of Mesoporous Silica Supported Silver and Gold Nanoparticles Against E. coli and S. aureus”. Some results are interesting and well-presented, which could make valuable contributions to the research community. However, I recommend some minor revisions on the following aspects of the manuscript.

The authors should include the numerical results of the physicochemical characterizations such as UV-Vis, TEM, SAED, FESEM, XRD, and FTIR—for the Ag@SBA-15, Au@SBA-15, and Au-Ag@SBA-15 nanocomposites in the abstract. General or qualitative information should be avoided. Additionally, the keywords should be revised to better reflect the core content and novelty of the manuscript.
On page 2, line no 56-59: “The MSPs exhibit unique characteristics such as high surface area, tunable pore size, high pore wall thickness, a large amount of silanol groups on the surface, good biodegradability/biocompatibility, and thermal/hydrothermal stability, as well as improved acid-base tolerance [12].” Authors should add some substantial results of high surface area, tunable pore size, high pore wall thickness, good biodegradability, and thermal stability of MSPs to support of this sentence with meaningful.
Why did the authors not provide any detailed literature review related to mesoporous and metal nanoparticles advantage in antibacterial and anticancer activities in the introduction section?
The most critical concerns are related to the novelty of Ag@SBA-15, Au@SBA-15, and Au-Ag@SBA-15 nanocomposites. Meanwhile, I wonder what is the unique advantage of Ag@SBA-15, Au@SBA-15, and Au-Ag@SBA-15 nanocomposites for antibacterial applications compared with other reports? This should be clarified by the authors.
Need to provide the purity of the used materials in the section 2.1. Need to add the schematic representation for the synthesis of Ag@SBA-15, Au@SBA-15, and Au-Ag@SBA-15 nanocomposites for the readers better understanding.
In Figure 1: Need to include the optical bandgap of the prepared Ag@SBA-15, Au@SBA-15, and Au-Ag@SBA-15 nanocomposites and explain in the text.
In Figure 2, the authors should label the distinct structures corresponding to Ag, Au, and SBA-15 in the TEM image of the Au-Ag@SBA-15 nanocomposite. Additionally, the authors should clarify why the d-spacing analysis for the Au-Ag@SBA-15 nanocomposite was not presented in Figure 2g. A correlation between the TEM observations and the XRD patterns particularly in terms of crystallographic facets is necessary. For a clearer understanding of the morphological features, the authors are also advised to include a TEM image of the bare SBA-15.
On page 6, lines 240–241, the authors state: “Here, we presented only the FESEM image of Ag@SBA-15 in Figure 3, since the rest nanocomposites have the same morphology.” However, it is unclear how the authors concluded that the remaining nanocomposites exhibit the same morphology, especially considering that TEM images of all the prepared samples are provided. For consistency and clarity, it is recommended that the authors include the FESEM images of the other samples in the revised version.
Why did the authors not provide any elemental composition analysis for the prepared Ag@SBA-15, Au@SBA-15, and Au-Ag@SBA-15 nanocomposites? It is essential to include EDAX or XPS analysis to confirm and discuss the elemental composition of the synthesized samples. The authors are strongly encouraged to incorporate this data and provide a detailed explanation of the elemental distribution in the revised manuscript.
Figure 4: Authors must calculate the lattice constant, lattice strain, and dislocation density of the prepared Ag@SBA-15, Au@SBA-15, and Au-Ag@SBA-15 nanocomposites and summarize in a tabular format with calculated optical bandgap. The crystallite size should be calculated using Williamson-hall plot and compare with derived results from Scherrer Eq. The crystallinity percentage and porosity for all samples should be calculated using XRD patterns. Furthermore, the crystallinity, phase percentages, and porosity of all samples should be estimated using Rietveld refinement.
Need to include the antibacterial activity plate photos of the prepared Ag@SBA-15, Au@SBA-15, and Au-Ag@SBA-15 nanocomposites.
Tables 1 and 2, along with Figure 6, present the same antibacterial activity results for the prepared nanocomposites. The authors should clarify why the same data is presented in multiple formats. If there is no added value in the repetition, it is recommended to consolidate the information to avoid redundancy.
The authors should propose a mechanism diagram illustrating the antibacterial activity of the Au-Ag@SBA-15 nanocomposite. This should include a detailed explanation of the roles played by reactive oxygen species (ROS) generation, the release of metal ions, and the influence of the composite's surface morphology on antibacterial performance. Including such a mechanism would significantly enhance the understanding of the nanocomposite’s antibacterial behavior.
In Table 3: Need to include the method of synthesis, structural and optical parameters of the reported nanocomposites.
The current conclusion does not accurately reflect the results of the present study, and therefore, the authors need to rewrite it. They may also consider comparing their results with similar studies in a tabular format to emphasize the advantages of their work.
More typographical errors are present in the manuscript, so the authors need to check them carefully. Additionally, the authors should improve the English language throughout the manuscript.

Author Response

Journal: Technologies

Manuscript title: Green Methodology for Producing Bioactive Nanocomposites of Mesoporous Silica Support for Silver and Gold Nanoparticles Against E. coli and S. aureus

Corresponding Authors: Una Stamenović and Vesna Vodnik

Type of manuscript: Research paper

Manuscript ID: technologies-3791367

Description of actions taken:

Italic – Reviewers’ comments

Green – Authors’ responses

RESPONSE TO REFEREES’ COMMENTS

We hope that the reviewers will find our responses to their comments satisfactory.

Reviewer 3:

The authors reports “Green Methodology for Producing Bioactive Nanocomposites of Mesoporous Silica Supported Silver and Gold Nanoparticles Against E. coli and S. aureus”. Some results are interesting and well-presented, which could make valuable contributions to the research community. However, I recommend some minor revisions on the following aspects of the manuscript.

Comment 1. The authors should include the numerical results of the physicochemical characterizations such as UV-Vis, TEM, SAED, FESEM, XRD, and FTIR—for the Ag@SBA-15, Au@SBA-15, and Au-Ag@SBA-15 nanocomposites in the abstract. General or qualitative information should be avoided. Additionally, the keywords should be revised to better reflect the core content and novelty of the manuscript.

Response to comment 1. The authors are thankful for the reviewer’s proposal, however, the number of words that could be in the Abstract is limited to 200, and it is impossible to include all the gained numerical results, but the ones considering particles sizes and the most important inhibitory concentrations. The keywords are revised according to the reviewer’s suggestion.

Comment 2. On page 2, line no 56-59: “The MSPs exhibit unique characteristics such as high surface area, tunable pore size, high pore wall thickness, a large amount of silanol groups on the surface, good biodegradability/biocompatibility, and thermal/hydrothermal stability, as well as improved acid-base tolerance [12].” Authors should add some substantial results of high surface area, tunable pore size, high pore wall thickness, good biodegradability, and thermal stability of MSPs to support of this sentence with meaningful.

Comment 3. Why did the authors not provide any detailed literature review related to mesoporous and metal nanoparticles advantage in antibacterial and anticancer activities in the introduction section?

Comment 4. The most critical concerns are related to the novelty of Ag@SBA-15, Au@SBA-15, and Au-Ag@SBA-15 nanocomposites. Meanwhile, I wonder what is the unique advantage of Ag@SBA-15, Au@SBA-15, and Au-Ag@SBA-15 nanocomposites for antibacterial applications compared with other reports? This should be clarified by the authors.

Response to comments 2, 3, and 4. The authors thank the reviewer. According to the reviewer’s suggestion, some specific results considering MSPs’ high surface area, pore sizes, and wall thicknesses, etc., are added to the Introduction part. The authors did a better literature review, and accordingly, new references and explanations are added. Additionally, the novelty of the nanocomposites presented in this research is highlighted through simple and environmentally friendly synthetic procedure, without any harmful byproducts, that, to the best of our knowledge, has not yet been presented. A more detailed explanation has been added to the Introduction.

Comment 5. Need to provide the purity of the used materials in the section 2.1. Need to add the schematic representation for the synthesis of Ag@SBA-15, Au@SBA-15, and Au-Ag@SBA-15 nanocomposites for the readers better understanding.

Response to comment 5. The purity of the used materials, together with their CAS numbers, are added to the Section 2.1 Materials.

Schematic representation for the synthesis of Ag@SBA-15, Au@SBA-15, and Au-Ag@SBA-15 nanocomposites is added in Section 3.1. Characterizations.

Comment 6. In Figure 1: Need to include the optical bandgap of the prepared Ag@SBA-15, Au@SBA-15, and Au-Ag@SBA-15 nanocomposites and explain in the text.

Response to comment 6. Metals as bulk do not possess a band gap, since their valence and conduction bands overlap – there is no forbidden gap between them. When metals are reduced to a nanometer size, with sizes larger than 2 nm, there is a collective intraband response visible as localized surface plasmon resonance (LSPR) in the absorption spectrum, in the UV/Vis part of the electromagnetic spectrum. However, in the case of clusters, i.e., particles smaller than 2 nm, with tens to hundreds of atoms, there is a discrete, molecule-like, HOMO–LUMO gap that disappears with increasing particle size.

References:

P. Halperin, Quantum size effects in metal particles, Rev. Mod. Phys. , Vol. 58, No. 3, July 1986;
Zhou, C. Zeng, Y. Chen, S. Zhao, M.Y. Sfeir, M. Zhu, R. Jin, Evolution from the plasmon to exciton state in ligand-protected atomically precise gold nanoparticles, Nature Communications, 7 (2016) 13240, doi: 10.1038/ncomms13240.

One may say that the “real” band gap, as in semiconductors, which is also one of their most important characteristics, is undefined for metal nanoparticles. For nanoparticles’ sizes in our research, which are much larger than 2 nm (8, 16, and 9 nm for AgNPs, AuNPs, and their bimetal in Ag@SBA-15, Au@SBA-15, and Au-Ag@SBA-15 nanocomposites, respectively), the relevant parameter is LSPR and accompanying values – peak energy and Full Width at Half Maximum (FWHM). The LSPR originating from AgNPs, AuNPs, and Au-AgNPs are visible at 432, 527, and 503 nm, respectively (Figure 1 in the Manuscript), while calculated peak energy values are 173.3, 361.9, and 152.5 nm. FWHM values are determined from corresponding absorption spectra, in OriginPro 9 64-bit, by the gadget Integrate, and are presented below.

Figure R1 FWHM values determined from absorption spectra of Ag@SBA-15, Au@SBA-15, and Au-Ag@SBA-15 nanocomposites, in OriginPro 9 64-bit.

Besides, taking into account the specific application of the presented nanocomposites in this research – antimicrobial effectiveness, beside LSPR position in the absorption spectra only for confirmation that these nanocomposites are produced, at the moment, other parameters are not relevant to us.

Comment 7. In Figure 2, the authors should label the distinct structures corresponding to Ag, Au, and SBA-15 in the TEM image of the Au-Ag@SBA-15 nanocomposite. Additionally, the authors should clarify why the d-spacing analysis for the Au-Ag@SBA-15 nanocomposite was not presented in Figure 2g. A correlation between the TEM observations and the XRD patterns particularly in terms of crystallographic facets is necessary. For a clearer understanding of the morphological features, the authors are also advised to include a TEM image of the bare SBA-15.

Response to comment 7. The distinct structures of Ag, Au, and SBA-15 are added in the TEM image of the Au-Ag@SBA-15 nanocomposite but were not labeled for Ag or Au, as these nanoparticles have similar crystallographic planes and lattice constant values [2.38 Å (Ag) and 2.31 Å (Au)]. Similarity is also visible in the Figure below (SAED image of both nanoparticles). Additionally, the d-spacing for the Au-Ag@SBA-15 nanocomposite is added in the new Figure 3g.

Comment 8. On page 6, lines 240–241, the authors state: “Here, we presented only the FESEM image of Ag@SBA-15 in Figure 3, since the rest nanocomposites have the same morphology.” However, it is unclear how the authors concluded that the remaining nanocomposites exhibit the same morphology, especially considering that TEM images of all the prepared samples are provided. For consistency and clarity, it is recommended that the authors include the FESEM images of the other samples in the revised version.

Response to comment 8. According to the reviewer’s suggestion, besides FESEM image of Ag@SBA-15 nanocomposite, the FESEM images of Au@SBA-15 and Au-Ag@SBA-15 nanocomposites, together with corresponding EDX graphs, are included in the new Figure 5.

Comment 9. Why did the authors not provide any elemental composition analysis for the prepared Ag@SBA-15, Au@SBA-15, and Au-Ag@SBA-15 nanocomposites? It is essential to include EDAX or XPS analysis to confirm and discuss the elemental composition of the synthesized samples. The authors are strongly encouraged to incorporate this data and provide a detailed explanation of the elemental distribution in the revised manuscript.

Response to comment 9. The XPS analysis of prepared Ag@SBA-15, Au@SBA-15, and Au-Ag@SBA-15 nanocomposites and appropriate discussion are added in Section 3.1. Characterizations.

Comment 10. Figure 4: Authors must calculate the lattice constant, lattice strain, and dislocation density of the prepared Ag@SBA-15, Au@SBA-15, and Au-Ag@SBA-15 nanocomposites and summarize in a tabular format with calculated optical bandgap. The crystallite size should be calculated using Williamson-hall plot and compare with derived results from Scherrer Eq. The crystallinity percentage and porosity for all samples should be calculated using XRD patterns. Furthermore, the crystallinity, phase percentages, and porosity of all samples should be estimated using Rietveld refinement.

Response to comment 10. The authors thank the Reviewer for the recommendation of various methods for estimating microstructural parameters by analyzing XRD diffraction patterns. Among all the recommended methods, the Le Bail fitting procedure was chosen to determine the basic structural and microstructural parameters because we don't require other structural parameters obtained through Rietveld refinement for our research.

The XRD patterns of Ag@SBA-15 and Au@SBA-15 nanocomposites were refined by the whole-pattern decomposition procedure (Le Bail fitting) using the FullProf software package [1, 2], taking into account the instrumental peak broadening. The applied analysis included refining all four characteristic peaks originating from a face-centered cubic lattice (S.G. Fm-3m): (111), (200), (220), and (311), and then calculating basic structural characteristics (cell parameters) and microstructural parameters (crystallite size and microstrain) based on the broadening of the diffraction peaks. The value of lattice parameter a was determined to be 4.08732(9) Å and 4.07870(5) Å for samples Ag@SBA-15 and Au@SBA-15, respectively. The formed nanocomposites Ag@SBA-15 and Au@SBA-15 consist of crystallites that are calculated to be nano-sized on the order of 9 nm and have a small amount of microstrain 0.05%, which represents the overall crystal imperfections (lattice strain, defects like dislocations and point defects). The results are included in the Manuscript.

A. Le Bail, H. Duroy, J.L. Fourquet, Ab-initio structure determination of LiSbWO6 by X-ray powder diffraction, Mater. Res. Bull. 23 (1988) 447–452.
J. Rodríguez-Carvajal, Recent advances in magnetic structure determination by neutron powder diffraction, Phys. B Condens. Matter 192 (1993) 55–69.

Comment 11. Need to include the antibacterial activity plate photos of the prepared Ag@SBA-15, Au@SBA-15, and Au-Ag@SBA-15 nanocomposites.

Response to comment 11. The authors were not able to do antibacterial analyses again, since it takes more time and organization than the extended deadline allows, just to take pictures of Petri dishes. This will remain as a reviewer's suggestion for the next work with these nanocomposites, planned to be done as a continuation of this manuscript.

Comment 12. Tables 1 and 2, along with Figure 6, present the same antibacterial activity results for the prepared nanocomposites. The authors should clarify why the same data is presented in multiple formats. If there is no added value in the repetition, it is recommended to consolidate the information to avoid redundancy.

Response to comment 12. The Tables were included in the manuscript for a clearer reading of the obtained results, while Figure 9 is only a pictorial representation of the tabular results. Since Tables are now expanded with some additional results, they are moved to the Supplementary Material, as Tables S2 and S3.

Comment 13. The authors should propose a mechanism diagram illustrating the antibacterial activity of the Au-Ag@SBA-15 nanocomposite. This should include a detailed explanation of the roles played by reactive oxygen species (ROS) generation, the release of metal ions, and the influence of the composite's surface morphology on antibacterial performance. Including such a mechanism would significantly enhance the understanding of the nanocomposite’s antibacterial behavior.

Response to comment 13. The mechanism of the nanocomposites antimicrobial activity has already been presented in the graphical abstract.

Comment 14. In Table 3: Need to include the method of synthesis, structural and optical parameters of the reported nanocomposites.

Response to comment 14. According to the Reviewer’ suggestion, Table 3 was expanded with data on synthesis and optical parameters, and now it is Table 1.

Comment 15. The current conclusion does not accurately reflect the results of the present study, and therefore, the authors need to rewrite it. They may also consider comparing their results with similar studies in a tabular format to emphasize the advantages of their work.

Response to comment 15. The conclusion is adjusted according to the results presented in the manuscript.

Comment 16. More typographical errors are present in the manuscript, so the authors need to check them carefully. Additionally, the authors should improve the English language throughout the manuscript.

Response to comment 16. The English was scrutinized by the Grammarly program, available as a free extension on the Google platform.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have made significant improvements, and the manuscript is now suitable for publication. I recommend it for acceptance.

Reviewer 2 Report

Comments and Suggestions for Authors

Reviewer 3 Report

Comments and Suggestions for Authors

In the revision, the authors addressed all of the concerns raised, resulting in an improved quality of the work.