Hello,
I'm trying to do a basic electrochemical biosensing (CV). Iv'e seen publications on using cyclic voltammetry and surface functionalization with self-assembled monolayers (SAM)s. So, my general question: If I functionalize the Au electrode with glucose oxidase via alkanethiol SAM, won't it make the Au surface to be impenetrable for ionic species and thus no current will flow?
Thank you,
Alex.
Hi Oleksiy Krupin
When a Au electrode is covered by a well formed alkanethiol SAM it will block redox species in solution from reaching the the Au surface, stopping electron transfer, so you would see no current flow. If, however, the redox species is tethered to the alkanethiol SAM (by a chemical bond, H bond, etc.) electron transfer between the redox species, in your case glucose oxidase, and the Au will occur. This happens via tunneling through the alkane back bone of your SAM. It is worth bearing in mind that the rate of electron transfer between the tethered redox species and the Au is affected by the length of the alakanethiol and the type of bond it has to the SAM.
Hope this helps.
Sam Catarelli Thank you, Sam. That is excellent! What if I use a mediator such as ferrocene or ruthenium derivatives?
Do you mean in the case that the mediator is in solution and you are interested in its interaction with the glucose oxidase functionalized Au? Or that the Au is functionalized with a ferrocene or ruthenium derivative?
I was thinking more of a mediator being in solution. Mainly because I cannot think of a way to attach ferrocene to the SAM and having it active. But it is a good question, and I suppose getting it onto the surface would be wiser. Is that so?
Hello Oleksiy Krupin
In addition to the excellent response of Sam Catarelli , I would say that it will very much depend on the quality and flatness of the surface and the selected SAM. In practice, the SAM will be full of defects and is very sensitive to the chain length (e.g., exhibiting odd-even effects). Furthermore, it will take time for the SAM to form, reorganise and then stabilise.
These papers could be interesting :
Article Odd-Even Effects in Charge Transport across Self-Assembled Monolayers
Article Properties of Self-Assembled Monolayers Revealed via Inverse...
Article The SAM, Not the Electrodes, Dominates Charge Transport in M...
Best regards,
Marie B.
As Marie Berthuel states, it will very much depend on the SAM.
You may find the following articles useful:
Article Optimization of DNA immobilization on gold electrodes for la...
Article Applications of Self-Assembled Monolayers for Biomolecular Electronics
Thank you all very much! I think I have enough boost to continue on my on with publications!.
Best Regards,
Alex.
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