Hi,
I'm working on an electrochemical biosensor integrated into a microfluidic system. The working and counter electrodes are gold, and the reference electrode is Ag/AgCl.
I'm planning to either immobilize thiolized nucleic acids on the bare gold WE surface, or use 11-mercaptoundecanoic acid SAM method to functionalize the WE surface for EDC-NHS coupling to proteins.
Due to the way the microfluidic device is fabricated, I may need to immobilize the biorecognition probes within closed channels (post-bonding). I also want to functionalize only the WE, while keeping the CE/RE uncoated.
Can anyone guide me on how this can be done?
Thank you,
Afiq
Hi Afiq,
You can make electrochemical desorption of 11-mercaptoundecanoic from the CE. The electrochemical desorption can be done by sweeping the potential between 0 to -1.4V in 0.1M KOH solution. You should optimize the potential window.
Good luck
I second Tili's answer.
I also had success performing electrochemical desorption in 0.1 M PBS by simply holding a strong negative potential (e.g., - 1.0 V vs. SCE) for 20-60 s. A flow is required to ensure that desorped species do not re-adsorp. Some care is needed with microelectrodes in optimising the conditions as delamination of the metal layer can occur.
Thank you Dr Tlili and everyone.
I have one additional question: as I flood the sensor surface with 11-MUA, will a SAM layer form on the AgCl surface too? Is a S-Cl bond possible, or can the sulfide displace the chloride from the Ag? (all of these are unfavorable outcomes)
I'm aware this question may sound silly, but my organic/inorganic chemistry knowledge is limited. Thank you for your patience :)
Afiq
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