Nanoliposome Use to Improve the Stability of Phenylethyl Resorcinol and Serve as a Skin Penetration Enhancer for Skin Whitening

Round 1

Reviewer 1 Report

Manuscript entitled," Nanoliposome use to improve the stability of phenylethyl res-orcinol and serve as a skin penetration enhancer for skin whitening’ aimed to prepare the phenylethyl resorcinol liposomes to improve the stability and serve as skin penetration enhancer for skin whitening.

 

comments:

1. The introduction is too long, it must be brief about skin and skin whitening agents.
2. The authors did not mention few studies that are relevant to their study, for example
3. https://dx.doi.org/10.1016%2Fj.ajps.2018.02.004
4. http://www.tandfonline.com/action/showCitFormats?doi=10.1080/10584587.2014.899873
5. In introduction, the authors must highlight the novelty, why their study is different from other similar publish studies?
6. What is the reason to do optimization with Box-Behnken design for this study? The authors can try different lipids with different surfactants for the preparation of liposomes?
7. Out of 17 NLPs formulation developed by BBD, where is the optimized formulation mentioned in the text?

Author Response

Dear Editor and Reviewers,

Thank you for your letter and for the reviewers’ comments concerning our manuscript entitled “Nanoliposome use to improve the stability of phenylethyl resorcinol and serve as a skin penetration enhancer for skin whitening” (Manuscript ID: coatings-1580222).

We thank the reviewers for the time and effort that they have put into reviewing our manuscript. Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made correction which we hope meet with approval.

The added portion was marked in red in the response, with the critical area bolded. Changes in the revision were shown using yellow highlight for review. In the following pages are our point-by-point responses to each of the comments.

 

Reviewer 1

Comments and Suggestions for Authors

Manuscript entitled, “Nanoliposome use to improve the stability of phenylethyl res-orcinol and serve as a skin penetration enhancer for skin whitening” aimed to prepare the phenylethyl resorcinol liposomes to improve the stability and serve as skin penetration enhancer for skin whitening.

 

1. The introduction is too long, it must be brief about skin and skin whitening agents.

Reply: We gratefully appreciate for your valuable suggestion. We have briefly introduced skin and skin whitening agents in the revised manuscript. Please check lines 44-71 in introduction.

 

2. The authors did not mention few studies that are relevant to their study, for example:https://dx.doi.org/10.1016%2Fj.ajps.2018.02.004;http://www.tandfonline.com/action/showCitFormats?doi=10.1080/10584587.2014.899873

Reply: Thank you so much for your important reminder. We apologize for the fact that the literature was not cited due to our oversight. We have cited these studies into introduction in the revised manuscript. Please check line 71, and line 87.

 

3. In introduction, the authors must highlight the novelty, why their study is different from other similar publish studies?

Reply: Thank you for your valuable advice. We have modified and highlighted the novelty in introduction in the revised manuscript. Please check lines 72-107 in introduction as follows:

“Recently, Amnuaikit et al[20]. developed a conventional liposome by thin film hydration method. Their conventional liposome had a big vesicle size and low EE. Panithi Rak-nam et al[21]. developed Liposomal Cream Formulation by modified ethanol injection method. However, these liposomes, ranged in size from 200-640 nm and were too large to penetrate the skin into the basal layer [21]”.

 

4. What is the reason to do optimization with Box-Behnken design for this study? The authors can try different lipids with different surfactants for the preparation of liposomes?

Reply: Question 1：In order to optimize and obtain the optimal formulation of PR-NLPs, we first investigated the main influencing factors of liposome preparation by single-factor experiments. Since the single factor experiment only considers the effect of a single factor on the formation of liposomes. We found that in the preparation of PR-NLPs, the conditions of liposome formation were related to multiple factors. Therefore, we use response surface experiments to analyze and seek the optimal process conditions.

Question 2：Thank you for your valuable suggestion that different lipids with different surfactants for the preparation of liposomes. We totally agree with you. In formulation optimization for the preparation of liposomes, different surfactants can be used. But the most widely used Tween series at present. To use the formulation faster in the production process, Tween 80 was selected as the surfactant in this study. In further work, we will optimize the preparation of liposomes by screening a variety of lipids and surfactants or in combination with lecithin.

 

5. Out of 17 NLPs formulation developed by BBD, where is the optimized formulation mentioned in the text?

Reply: The optimized formulation was mentioned as follow:

“After imposing constraints on three factors, the Design-Expert software proposed optimal PR-NLPs: A= 50 mg/mL, B= 17.5%, and C=10%” in lines 442-444.

Author Response File: Author Response.pdf

Reviewer 2 Report

Manuscript entitled," Nanoliposome use to improve the stability of phenylethyl res-orcinol and serve as a skin penetration enhancer for skin whitening’ aimed to prepare the phenylethyl resorcinol liposomes to improve the stability and serve as skin penetration enhancer for skin whitening.

The results are interesting and will be a good addition in the field of nanocarriers for the delivery of phenylethyl resorcinol. The manuscript can be accepted after fewer minor changes mentioned below. The manuscript is well written and results are elaborated comprehensively.

 

comments:

1. The introduction is too long, it must be brief about skin and skin whitening agents.
2. The authors did not mention few studies that are relevant to their study, for example
3. https://dx.doi.org/10.1016%2Fj.ajps.2018.02.004
4. http://www.tandfonline.com/action/showCitFormats?doi=10.1080/10584587.2014.899873

 

3. In introduction, the authors must highlight the novelty, why their study is different from other similar publish studies?
4. What is the reason to do optimization with Box-Behnken design for this study? The authors can try different lipids with different surfactants for the preparation of liposomes?
5. Out of 17 NLPs formulation developed by BBD, where is the optimized formulation mentioned in the text?

Author Response

Dear Editor and Reviewers,

Thank you for your letter and for the reviewers’ comments concerning our manuscript entitled “Nanoliposome use to improve the stability of phenylethyl resorcinol and serve as a skin penetration enhancer for skin whitening” (Manuscript ID: coatings-1580222).

We thank the reviewers for the time and effort that they have put into reviewing our manuscript. Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made correction which we hope meet with approval.

The added portion was marked in red in the response, with the critical area bolded. Changes in the revision were shown using yellow highlight for review. In the following pages are our point-by-point responses to each of the comments.

Reviewer 2

Comments and Suggestions for Authors

Manuscript entitled, “Nanoliposome use to improve the stability of phenylethyl res-orcinol and serve as a skin penetration enhancer for skin whitening” aimed to prepare the phenylethyl resorcinol liposomes to improve the stability and serve as skin penetration enhancer for skin whitening.

 

1. The introduction is too long, it must be brief about skin and skin whitening agents.

Reply: We gratefully appreciate for your valuable suggestion. We have briefly introduced skin and skin whitening agents in the revised manuscript. Please check lines 44-71 in introduction.

 

2. The authors did not mention few studies that are relevant to their study, for example:https://dx.doi.org/10.1016%2Fj.ajps.2018.02.004;http://www.tandfonline.com/action/showCitFormats?doi=10.1080/10584587.2014.899873

Reply: Thank you so much for your important reminder. We apologize for the fact that the literature was not cited due to our oversight. We have cited these studies into introduction in the revised manuscript. Please check line 71, and line 87.

 

3. In introduction, the authors must highlight the novelty, why their study is different from other similar publish studies?

Reply: Thank you for your valuable advice. We have modified and highlighted the novelty in introduction in the revised manuscript. Please check lines 72-107 in introduction as follows:

“Recently, Amnuaikit et al[20]. developed a conventional liposome by thin film hydration method. Their conventional liposome had a big vesicle size and low EE. Panithi Rak-nam et al[21]. developed Liposomal Cream Formulation by modified ethanol injection method. However, these liposomes, ranged in size from 200-640 nm and were too large to penetrate the skin into the basal layer [21]”.

 

4. What is the reason to do optimization with Box-Behnken design for this study? The authors can try different lipids with different surfactants for the preparation of liposomes?

Reply: Question 1：In order to optimize and obtain the optimal formulation of PR-NLPs, we first investigated the main influencing factors of liposome preparation by single-factor experiments. Since the single factor experiment only considers the effect of a single factor on the formation of liposomes. We found that in the preparation of PR-NLPs, the conditions of liposome formation were related to multiple factors. Therefore, we use response surface experiments to analyze and seek the optimal process conditions.

Question 2：Thank you for your valuable suggestion that different lipids with different surfactants for the preparation of liposomes. We totally agree with you. In formulation optimization for the preparation of liposomes, different surfactants can be used. But the most widely used Tween series at present. To use the formulation faster in the production process, Tween 80 was selected as the surfactant in this study. In further work, we will optimize the preparation of liposomes by screening a variety of lipids and surfactants or in combination with lecithin.

 

5. Out of 17 NLPs formulation developed by BBD, where is the optimized formulation mentioned in the text?

Reply: The optimized formulation was mentioned as follow:

“After imposing constraints on three factors, the Design-Expert software proposed optimal PR-NLPs: A= 50 mg/mL, B= 17.5%, and C=10%” in lines 442-444.

Author Response File: Author Response.pdf

Reviewer 3 Report

Author proposed a paper “Nanoliposome use to improve the stability of phenylethyl resorcinol and serve as a skin penetration enhancer for skin whitening” for the publication in Coatings, MDPI.

The paper has a good scientific soundness, and it was performed with a complete characterizations protocols.

In this paper, liposomes were prepared using ethanol injection method. This is a well consolidated method, but it requires a post-processing step, fundamental for ethanol evaporation. Therefore, this kind of process for liposomes preparation causes the presence of high level of solvent residue. Indeed, author declare that they have eliminated ethanol residue using rotary evaporation. Did the author measure the ethanol residue before and after this post-processing step operation?

I suggest adding an abbreviation list, according to the guidelines of this journal.

Some information is missing in the abstract, in my opinion. Here are some examples:

DHHB not defined in the abstract.

I would use only 1 decimal digit of mean size definition, not 3.54 nm. this is joust an average coming from multiple run on the instruments. it would be difficult to identify 0.04 nm.

Encapsulation efficiency is 96 % and 8.8 % respectively. why this difference?

What is the plateau time for drug release tests?

Line 34. do you have a reference report for this?

Lines 44-48 are introducing some concepts that are known in the literature; therefore, please cite this literature.

Line 66. Expressions such as “in vivo” and “in vitro” should be written in italique.

Line 68. Please add reference for this data of solubility in water.

Line 77. Maybe authors could expand this concept: drug carriers are conceited to protect drugs literally building layers of protection around them.

Line 84. “stay in the skin”. I would say “to be absorbed”, maybe.

Line 88. Add references on ethosomes, transferosomes and liposomes used to encapsulate and administrate PR.

Line 91. Authors are not clear about what kind of liposomes are referring to. 200 to 640 nm mean size, produced with which technique?

Line 94. It is not correct to say “a particle size of 120 nm”. It should be defined as “mean size of 120 nm”. Particle size distribution is defined as mean size plus/minus standard deviation.

Line 122. Double space here. Remove it.

Line 223. Define PBS buffer when you use this acronym for the first time. it is defined in line 225.

Line 331. “particle size”. no, it should be “mean size”, at least.

Figure 2 again describes particle size. I suggest adding also a particle size distribution, as correctly reported in Figure 5c.

Figure 5c. I would recall the axis: Liposomes, % or Particles, % for y axis; Mean diameter for x axis.

Figure 6, red curve, makes the reader think that the drug release is ending at 60% of drug content. What does this mean? that 40 % of drug remains confined in the drug carrier? Is this responsible for the accumulation of drug in local sites?

Line 648. I would say “in this study, we developed a method to produce nanoliposomes to facilitate…”. Is this facilitation in a certain manner damaged by the impossibility to release all the drug content, in some of the studied formulations?

Author Response

Dear Editor and Reviewers,

Thank you for your letter and for the reviewers’ comments concerning our manuscript entitled “Nanoliposome use to improve the stability of phenylethyl resorcinol and serve as a skin penetration enhancer for skin whitening” (Manuscript ID: coatings-1580222).

We thank the reviewers for the time and effort that they have put into reviewing our manuscript. Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made correction which we hope meet with approval.

The added portion was marked in red in the response, with the critical area bolded. Changes in the revision were shown using yellow highlight for review. In the following pages are our point-by-point responses to each of the comments.

Author Response File: Author Response.pdf

Reviewer 4 Report

The manuscript describes the nanoliposome developed for delivery of phenylethyl resorcinol for treatment of skin whitening. The main value of the study is comprehensive evaluation of physicochemical and biological properties of the novel nanocarriers. However, in my opinion, minor revision is required before acceptance of the manuscript for publication.

• some measuremets were conducted after sample dilution (e.g. AFM analysis, nanoparticle size, polydispersity index, and zeta potential analysis) - the exact concentration of the sample should be presened.
• Section 2.7.1., line 257 - should be probably 100 μL instead of 100 mL
• the number of samples used for each study should be presented. In fact, number of samples was shown only in the case of analysis presented in Table 3 and Fig. 6.
• the in vitro drug release process presented in Fig. 6 does not show the complete release of PR from liposomes. The process should be extended to present complete release of PR from liposomes
• the manuscript reqiures extended editorial correction

Author Response

Dear Editor and Reviewers,

Thank you for your letter and for the reviewers’ comments concerning our manuscript entitled “Nanoliposome use to improve the stability of phenylethyl resorcinol and serve as a skin penetration enhancer for skin whitening” (Manuscript ID: coatings-1580222).

We thank the reviewers for the time and effort that they have put into reviewing our manuscript. Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made correction which we hope meet with approval.

The added portion was marked in red in the response, with the critical area bolded. Changes in the revision were shown using yellow highlight for review. In the following pages are our point-by-point responses to each of the comments.

Reviewer 4

Comments and Suggestions for Authors

The manuscript describes the nanoliposome developed for delivery of phenylethyl resorcinol for treatment of skin whitening. The main value of the study is comprehensive evaluation of physicochemical and biological properties of the novel nanocarriers. However, in my opinion, minor revision is required before acceptance of the manuscript for publication.

 

1. some measuremets were conducted after sample dilution (e.g. AFM analysis, nanoparticle size, polydispersity index, and zeta potential analysis) - the exact concentration of the sample should be presened.

Reply: We agree with the reviewer’s point, for the characterization of PR-LPs, different tests have optimal sample requirements. In the SEM and AFM tests, the original samples were diluted 100 times for the best conditions for sample imaging. In the nanoparticle size, polydispersity index (PDI), the original sample was diluted 10 times before measurement. Zeta potential analysis is measured by the original sample without dilution. In the manuscript, we supplemented the sample dilutions for the different tests. The manuscript has also been revised. Please check line 173, and line 187.

 

2. Section 2.7.1., line 257 - should be probably 100 μL instead of 100 mL

Reply: Thank you so much for your careful check. We have corrected it. Please check lines 256-258.

 

3. the number of samples used for each study should be presented. In fact, number of samples was shown only in the case of analysis presented in Table 3 and Fig. 6.

Reply: We have added the number of samples in different experiments. Please check lines 412, 427, 544, 564, and 622.

 

4. the in vitro drug release process presented in Fig. 6 does not show the complete release of PR from liposomes. The process should be extended to present complete release of PR from liposomes

Reply: We toally understand the reviewer's concern. In in vitro drug release studies, to achieve controlled release and obtain prolonged-release information, we used the dialysis diffusion technique to investigate PR release from PR solution and PR-NLPs. In the study, the release of PR from PR-NLPs was rapid within 50 h, followed by a slower rate of release. Since PR is wrapped inside the phospholipid bilayer in PR-NLPs, during the drug release process, most of the PR will be released from the phospholipid bilayer to the outside. At the same time, there is also the behavior that PR is still wrapped inside the bilayer without being completely released to the outside. Due to the encapsulation of the phospholipid bilayer cannot allow this part of the drug to be detected through the dialysis bag, the cumulative release rate of PR-NLPs can not reach 100%. Based on this, we chose 0-72 h as the study time period in this study.

 

5. the manuscript reqiures extended editorial correction

Reply: Thank you for your valuable suggestion. We have checked and corrected.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Authors prepared a revised version of their paper about the production of nanoliposomes for skin penetrations applications for skin whitening, for the publication in Coatings, mdpi.

I noticed that some references have been added to the introduction section, as requested. Precisely, five.

Expressions such as “in vivo” and “in vitro” have been written in italique, as requested.

I still insist on adding an abbreviation list, in order to collect all the acronyms used in this paper: GIA, UV, UVA, L-DOPA, DQ, PR, DHHB, NLP, etc.

I would add a new reference on the new sentence of lines 77-78 about drug carriers.

Line 125. DHHB should be at least defined once.

Line 172. Is there any references confirming this preparation protocol?

Line 223. “we used”. I would not use personal expressions, but only impersonal forms to describe operations performed by authors.

Line 412. “mean”. I would write “mean value”

Figure 5c. Are you sure that this logarithmic scale is better than linear scale for x axis?

Author Response

Dear Editor and Reviewers,

Thank you for your letter and for the reviewers’ comments concerning our manuscript entitled “Nanoliposome use to improve the stability of phenylethyl resorcinol and serve as a skin penetration enhancer for skin whitening” (Manuscript ID: coatings-1580222).

We thank the reviewers for the time and effort that they have put into reviewing our manuscript. Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made correction which we hope meet with approval.

The added portion was marked in red in the response, with the critical area bolded. Changes in the revision were shown using yellow highlight for review. Attached are our point-by-point responses to each of the comments.

Author Response File: Author Response.pdf

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.