(E)-3-Heptyl-2-(4-thiomorpholinostyryl)benzo[d]thiazol-3-ium Iodide as Solvatochromic and Fluorogenic Dye for Spectroscopy Applications
, Meglena I. Kandinska 1, Anton Kostadinov 3, Laura Dietz 3 and Stanislav Baluschev 3,4Round 1
Reviewer 1 Report
In this submitted communication, Vasilev and wo-workers are reporting a thiazolium-based small molecule probe development and possible sensing applications. Based on the scope of the “Molbank” journal this work is suitable for publication in terms of new molecule synthesis and the spectroscopic properties study. However the claimed nucleic acid sensing and cytoskeleton staining abilities are highly questionable as authors haven’t provide any convincing evidence towards validating them.
(1). The observed DNA sensing ability is not prominent in the probe as the response is very weak. There are several good DNA binding molecules that has been published in many journals. I suggest authors to cite some of these recent publications: Photochemical & Photobiological Sciences 19 (2020): 1152-1159; Biosensors and Bioelectronics 189 (2021): 113381; Analyst 133.8 (2008): 984-991.
(2). There is no sufficient evidence provided by authors to prove that probe is staining cytoskeleton. This must be conducted through a series of confocal microscopy based experiments with colocalizing dyes.
Therefore, based on the nature of this journal and scope, reviewer understand that authors may not be able to perform all the experiments. Therefore, I strongly suggest authors to revise the “title of the manuscript” For simplicity and to avoid misleading authors can remove nucleic acid sensing and cytoskeleton staining from the title and simply use the term “spectroscopic applications” instead.
(3). The probe design is a donor-π-acceptor type which is highly useful in fluorophore designing . Therefore authors briefly highlight and discuss this probe architecture with some key references: Chemical Communications 58.71 (2022): 9855-9869
(4). Please provide all raw NMR data and HRMS data (with ppm error).
(5) Absorbance and emission for the probes must be recorded in different solvents and should provided in the manuscript.
Moderate English revision required.
Author Response
(1). The observed DNA sensing ability is not prominent in the probe as the response is very weak. There are several good DNA binding molecules that has been published in many journals. I suggest authors to cite some of these recent publications: Photochemical & Photobiological Sciences 19 (2020): 1152-1159; Biosensors and Bioelectronics 189 (2021): 113381; Analyst 133.8 (2008): 984-991.
Answer: With all my respect to the esteemed Reviewer the papers recommended are not suitable, because the fluorescence of the dyes reported is not measured in the same concentrations as ours (the fluorescence of the dyes in the recommended paper Photochemical & Photobiological Sciences 19 (2020): 1152-1159 is measured with conc. 1.10-5M). In addition, in the mentioned paper the fluorescence of the compounds is measured in ethanol, in our investigation – in water. In the same paper the slits of the excitation light and of the detection light are note mentioned. Additionaly it seems that the units are counts per seconds (cps) but in our case the units are (RFU). In summary in the recommended paper the dyes are not better than ours. In the other papers the dyes evaluated are attached on some surface or are included in some devices, which is not similar to our main idea. Actually, the increase of the fluorescence of our dyes 1 and 2 is not so high like the monomethine dyes as Thiazole orange for example, but the dyes have quite stable fluorescence in cells and very low intrinsic fluorescence, which is more important for the quality of one fluorescence probe. In order to bring a little more clarity in this direction, we allowed ourselves to note the increase in fluorescence in the corresponding figures for each of the dyes.
(2). There is no sufficient evidence provided by authors to prove that probe is staining cytoskeleton. This must be conducted through a series of confocal microscopy based experiments with colocalizing dyes.
Therefore, based on the nature of this journal and scope, reviewer understand that authors may not be able to perform all the experiments. Therefore, I strongly suggest authors to revise the “title of the manuscript” For simplicity and to avoid misleading authors can remove nucleic acid sensing and cytoskeleton staining from the title and simply use the term “spectroscopic applications” instead.
Answer: Many thanks to the Reviewer for the understanding. We completely agree with that remark, therefore we have changed the title of the manuscript to “(E)-3-Heptyl-2-(4-thiomorpholinostyryl)benzo[d]thiazol-3-ium iodide as Fluorogenic Dye for Nucleic acids Detection and Fluorescence Spectroscopy Applications”
(3). The probe design is a donor-π-acceptor type which is highly useful in fluorophore designing . Therefore authors briefly highlight and discuss this probe architecture with some key references: Asymmetric assembly of pyrazole and 1,2,3-triazole with a methylene bridge: regioisomerism and energetic properties† Jin Xiong, Jinxiong Cai, Qi Lai, Ping Yin and Siping Pang, Chemical Communications 58, 71 (2022): 9855-9869. doi: https://doi.org/10.1039/D2CC02412H.
Answer: This is far from the focus of the present work.
(4). Please provide all raw NMR data and HRMS data (with ppm error).
Answer: All analytical data that we can obtain for the moment were provided in the ESI file with improved ppm resolution.
(5) Absorbance and emission for the probes must be recorded in different solvents and should provided in the manuscript.
Answer: The absorption spectra in different solvents were provided and discussed in the Results and discussion section. The fluorescence of the dyes in most of the solvents (except water) is near zero therefore is meaningless to demonstrate them now. We plane more experiments with molecular baskets and different pH. The synthesis of a larger series of similar dyes is in progress and the more precise study of their photophysical properties will be performed and discussed in another work. The studies reported here represent pilot research.
Comments on the Quality of English Language
Moderate English revision required.
Submission Date
30 June 2023
Date of this review
11 Jul 2023 21:24:34
Reviewer 2 Report
This article synthesized Dye 2 for comparison with Dye 1, and the test results of UV-VIS absorption spectra and fluorescence spectra are accurate, illustrated, and meaningful. There is a few questions as follows.
1. line 62. The I-ion writing of molecules is not standardized. Please check the entire text.
2. line 68, there should be Figure 2 after Dye 2.
3. What is the basis for choosing this 7-carbon chain？
4. Only one substituent has been changed as a reference in the article, and it is recommended to add different carbon chains for comparison, making the paper more meaningful.
No.
Author Response
- line 62. The I-ion writing of molecules is not standardized. Please check the entire text.
Answer: The I-ion was corrected in the Figure 1.
- line 68, there should be Figure 2 after Dye 2.
Answer: Now is Figure 3 and it is added to the text.
- What is the basis for choosing this 7-carbon chain？
Answer: We were curious to understand the role of the substituents attached to the benzothiazolium moiety of the fluorochrome. For a clearer result, we chose two fragments with a significant difference in the lengths of the alkyl chains. The difference of the binding is obvious.
- Only one substituent has been changed as a reference in the article, and it is recommended to add different carbon chains for comparison, making the paper more meaningful.
Answer: Thanks for the advises. These are only initial studies. We are on the way for bigger series of these dyes with many different substituents. The work is in progress and will be published elsewhere.
Comments on the Quality of English Language
No.
Submission Date
30 June 2023
Date of this review
19 Jul 2023 13:39:04
Round 2
Reviewer 1 Report
I am not satisfied with author's response with the revision, as they have not answered my concerns sufficiently. Therefore, I cannot recommend current revised version for acceptance unfortunately.
In addition, author's have not provided sufficient explanation for the photophysical behavior of the probe.
Moderate language check required.
Author Response
(1). The observed DNA sensing ability is not prominent in the probe as the response is very weak. There are several good DNA binding molecules that has been published in many journals. I suggest authors to cite some of these recent publications: Photochemical & Photobiological Sciences 19 (2020): 1152-1159; Biosensors and Bioelectronics 189 (2021): 113381; Analyst 133.8 (2008): 984-991.
Answer: With all my respect to the esteemed Reviewer the papers recommended are not suitable, because the fluorescence of the dyes reported is not measured in the same concentrations as ours (the fluorescence of the dyes in the recommended paper Photochemical & Photobiological Sciences 19 (2020): 1152-1159 is measured with conc. 1.10-5M). In addition, in the mentioned paper the fluorescence of the compounds is measured in ethanol, in our investigation – in water. In the same paper the slits of the excitation light and of the detection light are note mentioned. Additionaly it seems that the units are counts per seconds (cps) but in our case the units are (RFU). In summary in the recommended paper the dyes are not better than ours. In the other papers the dyes evaluated are attached on some surface or are included in some devices, which is not similar to our main idea. Actually, the increase of the fluorescence of our dyes 1 and 2 is not so high like the monomethine dyes as Thiazole orange for example, but the dyes have quite stable fluorescence in cells and very low intrinsic fluorescence, which is more important for the quality of one fluorescence probe. In order to bring a little more clarity in this direction, we allowed ourselves to note the increase in fluorescence in the corresponding figures for each of the dyes.
(2). There is no sufficient evidence provided by authors to prove that probe is staining cytoskeleton. This must be conducted through a series of confocal microscopy based experiments with colocalizing dyes.
Therefore, based on the nature of this journal and scope, reviewer understand that authors may not be able to perform all the experiments. Therefore, I strongly suggest authors to revise the “title of the manuscript” For simplicity and to avoid misleading authors can remove nucleic acid sensing and cytoskeleton staining from the title and simply use the term “spectroscopic applications” instead.
Answer: Many thanks to the Reviewer for the understanding. We completely agree with that remark, therefore we have changed the title of the manuscript to “(E)-3-Heptyl-2-(4-thiomorpholinostyryl)benzo[d]thiazol-3-ium iodide as Solvatochromic and Fluorogenic Dye for Spectroscopy Applications”
(3). The probe design is a donor-π-acceptor type which is highly useful in fluorophore designing . Therefore authors briefly highlight and discuss this probe architecture with some key references: Asymmetric assembly of pyrazole and 1,2,3-triazole with a methylene bridge: regioisomerism and energetic properties† Jin Xiong, Jinxiong Cai, Qi Lai, Ping Yin and Siping Pang, Chemical Communications 58, 71 (2022): 9855-9869. doi: https://doi.org/10.1039/D2CC02412H.
Answer: This is far from the focus of the present work.
(4). Please provide all raw NMR data and HRMS data (with ppm error).
Answer: All analytical data that we can obtain for the moment were provided in the ESI file with improved ppm resolution.
(5) Absorbance and emission for the probes must be recorded in different solvents and should provided in the manuscript.
Answer: The absorption spectra in different solvents were provided and discussed in the Results and discussion section. The fluorescence of the dyes in most of the solvents (except water) is near zero therefore is meaningless to demonstrate them now. We plane more experiments with molecular baskets and different pH. The synthesis of a larger series of similar dyes is in progress and the more precise study of their photophysical properties will be performed and discussed in another work. The studies reported here represent pilot research.
Comments on the Quality of English Language
Moderate English revision required.
Reviewer 2 Report
No suggestion.
It's appropriate.
Author Response
Thank you very much for your comments.
