Recently, I am working on a new project for developing the glucose biosensor based on electrochemical measurement. I don't have too much experience in electrochemical analysis and electrochemical biosensors, so I would like to ask some questions and I hope some experienced researcher can help me out.
1. I read several papers related to the glucose biosensor and in the papers, most of them were using the Prussian Blue as the mediator for transferring the electron from the enzyme (glucose oxidase) to the electrode. However, the synthesis of the Prussian Blue required dissolving the K3[Fe(CN)6] in the hydrogen chloride solution ( which is a strongly acidic solution). And I am worried about is there any risk of mixing the K3[Fe(CN)6] with HCl? For example, is there any possibility that there will be the release of HCN?
2. I want to use chronoamperometry for the measurement but I don't know how to select the appropriate potential for the measurement? I think I will do the measurement with the selected potential and based on the current change, I can determine the glucose concentration. So should I do the CV firstly and then which potential should I choose? Potential of peak current in the CV or others?
Thank you so much for the reading. And please give me some ideas. Thank you in advance.
Hello,
1.) You do not need to worry about the release of HCN gas when adding potassium ferrocyanide to HCl. The cyano groups are tightly bound to Fe (so much so, that it's non-toxic; in fact, potassium ferrocyanide is a food additive).
2.) In order to perform chronoamperometry (more accurately constant potential amperometry), you will first perform a CV of the mediator you intend to use. The applied potential for your chronoamperometry experiment should be set at ~ 150 mV above the peak anodic potential. The applied potential must be more oxidizing than your mediator in order to drive electron transfer.
I hope this helps, and good luck!
1 Don't worry about the addition
2 You can use the CVs to determine the oxidation potentials for you substance first. Then use the DPV or SWV to get the oxidation peak current values. CVs is the most reliable techniqe for potentials analysis and the SWV or DPV has lower background currents, which are more accurate in peak currents than CVs. You can read the book below. Also a latest work finished by our team took the strategy above, just for reference.
ELECTROCHEMICAL METHODS
Fundamentals and Applications. Allen J. Bard
Article A Novel Modification to Boron-Doped Diamond Electrode for En...
https://www.sciencedirect.com/science/article/pii/S0008622320307752?via%3Dihub
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