N-S-co-Doped Carbon Dot Blue Fluorescence Preparation and Baicalein Detection
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe present works reports the synthesis of blue-emitting N-S-co-doped carbon quantum dots (CDs), for the detection of baicalein. CDs were prepared through the hydrothermal approach employing L-cysteine and sodium citrate as precursors. PL-emission, FT-IR, TEM, and XPS techniques were employed for CDs characterization. PL-emission quenching was studied and developed for baicalein determination. Real-world analyses on human blood and urine were also reported.
The results look reasonable and support the observed trends; the treated arguments are well-described and supported by adequate references. However, there are some points not clear and force me to suggest publication on Inorganics only after some revisions.
Some remarks:
- XPS analyses: the authors are invited to discuss the deconvolutions of the XPS peaks with particular care to the nitrogen and sulfur ones (see https://doi.org/10.1016/j.electacta.2021.138557, https://doi.org/10.1016/j.matchemphys.2019.04.071).
- UV-vis analyses: The authors are invited to discuss the UV-vis spectra, briefly reported in Fig.10, in section 2.2 together with the PL-determinations. From Fig. 10 the UV-vis spectrum of CDs seems to show three peaks (ca 250 nm, p-p* transitions, ca 320 nm and ca 370 nm n-p* transitions). The transition of the C=O and C=N groups are usually reported as n-p* transitions… https://doi.org/10.1016/j.electacta.2021.138557, https://doi.org/10.1002/chem.202000763.
- PL-analyses: pg 4 lines 114-117, the PL-quenching may be due to CDs’ aggregation with the increasing concentration… Fig. 5d the authors are invited to discuss the lifetime decay curve of CDs (https://doi.org/10.1002/chem.202000763, https://doi.org/10.1016/j.carbon.2015.08.066). Why the authors collected the lifetime decay curve at 320 nm excitation and not at 365 nm?
- pH dependence: Did the authors observe the pH-dependence in the UV-vis responses? A possible explanation of the pH-dependence may be the protonation/deprotonation of N-centers present in the CDs honey-comb matrix (https://doi.org/10.1016/j.electacta.2021.138557). The authors are invited to discuss.
- Section 2.4 could be discussed in the introduction and in the materials and methods sections.
Author Response
Response to Reviewer 1 Comments:
Point 1: XPS analyses: the authors are invited to discuss the deconvolutions of the XPS peaks with particular care to the nitrogen and sulfur ones (see https://doi.org/10.1016/j.electacta.2021.138557, https://doi.org/10.1016/j.matchemphys.2019.04.071).
Response 1: This part is added into section 2.1. The new reference is 19.
Point 2: UV-vis analyses: The authors are invited to discuss the UV-vis spectra, briefly reported in Fig.10, in section 2.2 together with the PL-determinations. From Fig. 10 the UV-vis spectrum of CDs seems to show three peaks (ca 250 nm, p-p* transitions, ca 320 nm and ca 370 nm n-p* transitions). The transition of the C=O and C=N groups are usually reported as n-p* transitions… https://doi.org/10.1016/j.electacta.2021.138557, https://doi.org/10.1002/chem.202000763.
Response 2: From figure 10, there are three peaks (ca 250 nm, p-p* transitions, ca 320 nm and ca 370 nm n-p* transitions) in UV-vis spectrum of CDs. The transition of the C=O and C=N groups are both n-p* transitions. The new reference is 33.
Point 3: PL-analyses: pg 4 lines 114-117, the PL-quenching may be due to CDs’ aggregation with the increasing concentration… Fig. 5d the authors are invited to discuss the lifetime decay curve of CDs (https://doi.org/10.1002/chem.202000763, https://doi.org/10.1016/j.carbon.2015.08.066). Why the authors collected the lifetime decay curve at 320 nm excitation and not at 365 nm?
Response 3: From the attenuation curve of fluorescence intensity in figure 5d, when the fluorescent substance is excited, most of excited state molecules return to ground state rapidly. But some molecules return to ground state in several times fluorescence lifetime delay. The new reference is 22. In our laboratory, we only have 320nm laser device.
Point 4: pH dependence: Did the authors observe the pH-dependence in the UV-vis responses? A possible explanation of the pH-dependence may be the protonation/deprotonation of N-centers present in the CDs honey-comb matrix (https://doi.org/10.1016/j.electacta.2021.138557). The authors are invited to discuss.
Response 4: The pH-dependence in UV-vis responses is the protonation/deprotonation of N-centers present in CDs honey-comb matrix. The new reference is 21
Point 5: Section 2.4 could be discussed in the introduction and in the materials and methods sections.
Response 5: It has been adjusted to materials and methods sections.
Reviewer 2 Report
Comments and Suggestions for AuthorsReview on manuscript inorganics-2965516
The article is about the fabrication of a blue-emitting CDs and their interaction witkh a small biomolecule baicalein.
The results are intersting ad the results are worth to be publish, I have some minor comments.
1. Why this biomolecule baicalein? The authors provided negligible info on quenching mechanism. Is there any structural explanation?
2. Fig. 6. What is the concentration of CDs? Missing
3. Fig. 2. This figure seems as Graphical abstract. Please presents only the synthesis protocol.
Comments on the Quality of English Language
Acceptable
Author Response
Response to Reviewer 2 Comments:
Point 1: Why this biomolecule baicalein? The authors provided negligible info on quenching mechanism. Is there any structural explanation?
Response 1: Baicalein is glucuronide, which possesses weak acidity. It can dissolve in alkaline solution, from which the sodium salt forms. According to the acidification in extraction solution, the baicalein is free precipitation. The info on quenching mechanism is added in section 2.2.
Point 2: Fig. 6. What is the concentration of CDs? Missing.
Response 2: The concentration of CDs is 100μg mL–1
Point 3: Fig. 2. This figure seems as Graphical abstract. Please presents only the synthesis protocol.
Response 3: Every thumbnail.in figure 2 is drawn by ourselves. Finally all the thumbnail combine into figure2.
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe authors have significantly improved the manuscript from previous version. The detail statement and corrections make the work acceptable to be published in Inorganics. The work is useful for most researchers working on the development of sensors based on carbon quantum dots. The recommendation is accepted in its present form.
