I am working on a glucose oxidase/ZnO thin film Biosensor. I am able to produce CV showing increasing Ipa with increasing concentration of glucose in solution. But I am not getting any current step increase in amperometric it curve with increasing glucose concentration. Kindly suggest the solutions for this problem.
Apply constant potential and maintain constant stirring. Inject the analyte solution at regular interval of time and increase the concentration equally at each steps. Hope this will help you.
for performing Amperometry experiment at any constant potential first stable the electrode at minimum noise under constant stirring in the cell (approximate 15 minute). and then adding the particular concentration after regular interval. Please check the potential difference between working with reference and counter electrode for minimum noise in base current.
Thanks for the reply..... but i am performing it the same way as mentioned, but still not getting any increse in current..
Whats the anodic potential at which oxidation peak appear or increases with next higher cocentration.
Hi. You must apply constant potential Higher than peak potential obtained in CV experiment.
I think that you detect the H2O2 produced by the enzimatic reaction GOx-glucose i.e. a classical biosensor. If you are looking for amperometric detection you should follow these steps:
1 - Hydrodinamic curve for H2O2: run amperometric experiments where the potential will be increased progressively (for instance; since 0.0 to 0.8V, steps 0.05V, 60 seg). First, the background experiment (only buffer) and, after, the same experiment for H2O2 1mM in the buffer. Then, plot the currents vs the potentials for each case, and select the best potential for the H2O2 detection. It is the right way to optimize the amperometric H2O2 detection. CV is useful and you can use as a first approximation but kinetic limitations are present in this criterion and it is not absolutely correct in biosensors.
2 – Hydrodinamic curve for glucose: you must do the same but using glucose+buffer and glucose+GOx+buffer.
The Step 1 is very important because you can get an idea about the sensitivity of your electrode in the H2O2 detection. Perhaps, your GOx produces low H2O2 concentrations and you can’t detect the H2O2 of your enzymatic reaction. Anyway, the procedure for the study of an amperometric detection is widely reported and there are a lot of papers about it, for example, our most recent paper for a lactate biosensor (Biosensor & Bioelectronics 56 (2014) 345) . I hope that it will be useful for you.
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