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Abstract Details

(2020) Mechanisms of Enhanced Antibacterial Activity by Reduced Chitosan-Intercalated Nontronite

Xia Q, Wang X, Zeng Q, Zhu Z & Dong H

https://doi.org/10.46427/gold2020.2917

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13b: Room 4, Wednesday 24th June 07:03 - 07:06

Listed below are questions that have been submitted by the community that the author will try and cover in their presentation. To submit a question, ensure you are signed in to the website. Authors or session conveners approve questions before they are displayed here.

Submitted by Ruggero Vigliaturo on Monday 22nd June 15:41
Can you provide some information about the micro- and nano-structure of the used chitosan/clays?
Sure. We have provided the XRD structure of the used chitosan-intercalated NAu-2 in the SI in our recently published paper (https://pubs.acs.org/doi/abs/10.1021/acs.est.9b07185). Moreover, 3 times recycled clay structure was provided in the SI section in our previously published paper (https://pubs.acs.org/doi/abs/10.1021/acs.est.7b00726). Hope that helps!

Submitted by Michael O'Shea on Tuesday 23rd June 14:31
In a natural system, what factors could complicate this antibacterial activity? Do you plan to test this process using any other clays?
Thanks for your question. A lot of factors in natural scenario, may contribute to the antibacterial activity of the clays, like pH, clay surface charge, ionic strength, anion/cation types. The effect of pH has been discussed in our previously published papers (https://pubs.acs.org/doi/abs/10.1021/acs.est.7b00726), and the effect of clay surface charge on this paper (https://pubs.acs.org/doi/abs/10.1021/acs.est.9b07185). Papers on the effects of ionic strength, anion/cation types are in submission (kind of conplicated to say in a few words). Also, other types of iron-containing clay was tested, manuscript on that was submitted.

Submitted by Inna Kurganskaya on Tuesday 23rd June 23:14
Thank you for the exciting and colorful presentation! I have a few questions. How the charge reversal was done for clay particles? What is the difference between rN-Au-2 and rC-Au-2 materials that generated antibacterial effect at pH=6 for r-C-Au2? How both of them were prepared? I see that one of them formed floccules, that means it some charging and coagulation involved. Is this the primary reason for antibacterial effect at pH 6, or it is something to do with -OH/Fe ratio?


Submitted by Qingyin Xia on Wednesday 24th June 15:01
Thanks for your questions. CHitosan was easilyed protonated at acidic pH, and can be intercalated into the interlayer of NAu-2, thus reversing the surface charge of the clay. Details on the steps of chitosan intercation can be found in the SI section of this paper (https://pubs.acs.org/doi/abs/10.1021/acs.est.9b07185). Due to the intercalation of chitosan (one type of polysaccharide), it may scavenger part of the ROS generated on the clay surface. NAu-2 is one type of natural nontronite, rNAu-2 is the chemically-reduced form of NAu-2, via sodium dithionite reduction. C-NAu-2 was prepared via chitosan intercation, rC-NAu-2 is the chemically-reduced form of C-NAu-2, via sodium dithionite reduction. Yeah, we agree with your point in the formation of floccules, which was discussed in above-mentioned paper. The reason for the most efficient antibacterial effect at pH 6 was complicated, definitely was associated the the production of ROS, which was also at its peak yield at pH 6 over the range of 6-8. We believe that the concentration of soluble ions were also important for its observed strongest antibacterial activity at oH 6.


Submitted by Qingyin Xia on Wednesday 24th June 15:02
Thanks for your questions. Chitosan was easilyed protonated at acidic pH, and can be intercalated into the interlayer of NAu-2, thus reversing the surface charge of the clay. Details on the steps of chitosan intercation can be found in the SI section of this paper (https://pubs.acs.org/doi/abs/10.1021/acs.est.9b07185). Due to the intercalation of chitosan (one type of polysaccharide), it may scavenger part of the ROS generated on the clay surface. NAu-2 is one type of natural nontronite, rNAu-2 is the chemically-reduced form of NAu-2, via sodium dithionite reduction. C-NAu-2 was prepared via chitosan intercation, rC-NAu-2 is the chemically-reduced form of C-NAu-2, via sodium dithionite reduction. Yeah, we agree with your point in the formation of floccules, which was discussed in above-mentioned paper. The reason for the most efficient antibacterial effect at pH 6 was complicated, definitely was associated the the production of ROS, which was also at its peak yield at pH 6 over the range of 6-8. We believe that the concentration of soluble ions were also important for its observed strongest antibacterial activity at oH 6.


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