Formation of Water-Free Cavity in the Process of Nafion Swelling in a Cell of Limited Volume; Effect of Polymer Fibers Unwinding

Round 1

Reviewer 1 Report

Reviewer report on Manuscript Draft entitled ‘Structure and Properties of the Exclusion zone of Nafion: Swelling in a Constrained Volume’

This work was motivated by the phenomenon of Nafion swelling in water. Colloidal particles are repelled by an “Exclusion zone” that extends several hundreds of microns from the solid polymeric surface. When Nafion's membrane swells in a cell, the volume of which is comparable to the volume of the membrane itself, various dynamic modes are realized due to the effect of "unwinding" of polymer fibers into the surrounding liquid, that are constrained by the cell windows. In this research the endothelial surface layer (ESL) and unwinding of DNA are given as examples to show that what authors propose as a model for the Nafion Exclusion Zone (EZ) is not impossible. The Nafion-like properties should be shared with the glycocalyx of living tissue underpinning the endothelial surface layer. Authors thinks that the same is true for the exothelial layers of electric fish, eels, platuses, and other creatures that use electric shocks to stun prey.

The manuscript is well written and investigations are well addressed from variuos points of view, presented discussion and insights are very interesting. The research is in scope of the journal. Therefore, the manuscript can be published after some corrections and improvements:

It was demonstrated that Nafion is increasing performance of some enzymatic electrochemical sensors (Bioelectrochemical sensor based on PQQ-dependent glucose dehydrogenase. Sensors and Actuators: B. Chemical 2004, 100, 3, 387–394.) what can be explained by recent work with this recent work ‘Structure and Properties of the Exclusion zone of Nafion: Swelling in a Constrained Volume’, therefore, this fact should be also mentioned in the manuscript and supported by this reference, because authors were not able to explain all advantages of nafion, which additionally are based on ‘swelling’ and retaining water in the structure of nafion, hence this water is critical to retain native structure of enzyme and therefore enzyme PQQ-dependent glucose dehydrogenase immobilized within nafion has greater catalytic activity and other characteristics. Recent work by authors clarifies these effects.

Author Response

The referee indicated that in our work it was demonstrated that Nafion is increasing performance of some enzymatic electrochemical sensors (Bioelectrochemical sensor based on PQQ-dependent glucose dehydrogenase. Sensors and Actuators: B. Chemical 2004, 100, 3, 387–394.) what can be explained by recent work with this recent work ‘Structure and Properties of the Exclusion zone of Nafion: Swelling in a Constrained Volume’, therefore, this fact should be also mentioned in the manuscript and supported by this reference, because authors were not able to explain all advantages of nafion, which additionally are based on ‘swelling’ and retaining water in the structure of nafion, hence this water is critical to retain native structure of enzyme and therefore enzyme PQQ-dependent glucose dehydrogenase immobilized within nafion has greater catalytic activity and other characteristics. Recent work by authors clarifies these effects.

We agree with this remark. In the Discussion section, we specially analyze the effect of Nafion's fiber unwinding in the context of applying this effect to increasing performance of some enzymatic electrochemical sensors; here we cite the article Malinauskas, A.; Kuzmarskytė, J.; Meškys, R.; Ramanavičius, A. Bioelectrochemical sensor based on PQQ-dependent glucose dehydrogenase, Sensors and Actuators B, 2004, 100, 387–394. 

Reviewer 2 Report

The manuscript "Structure and Properties of the Exclusion zone of Nafion: Swelling in a constrained volume" is not well written with extensively introduction as well a very questionable form instead of explaining their theroies refering to references. So far the subject has been published before from same authors which is not reason to reject but there must be some sort of outline where the novelty is.

The Figures shown here looks like copies from somewhere with no good resolutions, please replace those.

From the scientific content the readers need comparable same authors previous work a more concise interpretation. As example in section 3.4 the existance on nanobubbles playing a role appears there the first time but not mention in abstract nor introduction. The research is not bad but the presentation needs to be improved with shorten introduction, concise scientific interpretation as well explanation what is novel and not shown before.

Author Response

The Figures shown here looks like copies from somewhere with no good resolutions, please replace those.

All experimental plots were obtained using the OriginPro 2015 package, and then converted to TIF format. Photos have also been converted to TIF format.

From the scientific content the readers need comparable same authors previous work a more concise interpretation. As example in section 3.4 the existence on nanobubbles playing a role appears there the first time but not mention in abstract nor introduction.

In the new version, we specially mention in the Abstract that in this work we will investigate the effect of nanobubbles on the formation and collapse of a cavity. In addition, section 3.4 in the new version is entitled "Contribution of gas nanobubbles in the cavity formation / collapse".

The research is not bad but the presentation needs to be improved with shorten introduction, concise scientific interpretation as well explanation what is novel and not shown before.

In the Conclusion section of the new version we specially highlighted the new results obtained in this work.

Extensive editing of English language and style required.

The manuscript was read by a native speaker: our co-author Professor Barry Ninham from the Australian National University. We hope the quality of the English language has been significantly improved.