Cholesteric Liquid Crystal Photonic Hydrogel Films Immobilized with Urease Used for the Detection of Hg2+
Round 1
Reviewer 1 Report
The manuscript is interesting and in the trend of research.
English must be corrected as in Figure 10, 11, and in the text in few places.
The article can be published after minor revisions.
Author Response
Please check the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The authors proposed the use of polyacrylic acid (PAA) hydrogel to detect the presence of mercury ions based on the color change in the presence of urease enzyme. Even though the idea sounds interesting, few issues need to be addressed.
- It is not clear if other research groups use photonic gel (eg PAA) for the detection of mercury ions.
- Control experiments in the presence of other ions that mercury are missing
- Why are the reflection spectra inverted? For each figure, measurements should be recorded for 3 different gels in the presence of each type of mercury concentration to verify the repeatability
- In figures 7 and 11, the error bars are missing
- Larger scale photos of gels in the presence of selected mercury concentrations and various urease concentrations should be reported including a scale bar
- What is the stability over time of the colors on the gel? Possible interferences in the measurements?
- The title is confusing: what do the authors mean by “cholesteric liquid crystal photonic hydrogel films” do they use a gel or the liquid phase for optical measurements?
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
The manuscript describes a Hg2+ sensing method based on a polyacrylic acid liquid crystal photonic hydrogel containing immoblized urease. Hg2+-induced inhibition of urease-catalyzed urea hydrolysis led to suppression of pH increase from the production of NH3, which impacted the reflected light wavelength of the materials. The approach is novel and the Hg2+ sensing performance is robust with a detection limit of 10 nM. However, the authors should address the following issues before publication:
(1) Given that a pH change resulting from NH3 formation is required to induce a color change of the materials, would this material still work in acidic or basic real-world samples where prior pH adjustment or use of a buffering agent is necessary? A comment on this point is needed.
(2) Have the authors studied the interference from other metal ions, such as Cu(II)? If not, at least the selectivity of the method should be briefly discussed in the manuscript.
(3) The manuscript requires a careful proof-read to improve the English language. I found the following issues:
Line 12, insert "with" between "film" and "immobilized"
Line 14, "hydrolyzes" should be "hydrolyze"
Line 18, duplication between "displacement" and "change"
Line 37, delete "however"
Line 39, "method" should be "methods"
Line 40, "large-scale" should be "large"
Line 53, re-phrase "which is reflected to...eye"
Line 96, "elevatory" should be "elevated" Add "class of" to the end of this line
Line 180, delete space from "0.5 %"
Line 191, change "have" to "with"
Line 192, change "its" to "a". Delete "was"
Line 199, add "colors" after "green"
Line 207, "presenting" should be "displays"
Line 219, "improve" should be "improves"
Line 220, change "is more conductive for" to "facilitates"
Line 226, a colour change was described but no information on what conditions (from pH x to pH y) the colour change was referring to
Line 265, "displayed" should be "changed"
Line 269, what does "the platform value" mean?
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
The authors answered most of the reviewer' questions. The article is ready for publication.
Reviewer 3 Report
The revised manuscript can be published.
