Our biosensor works acceptably when using serum. However we are reading currents even higher than baseline (DPV in feCN6) when we have switched to plasma. The DPV reading is the same when plasma and EDTA plasma is used. Does anyone knows what could contribute to this reading?
Dear Patricia,
The best way to understand why you observed a higher current upon switching from the serum to plasma is due to the differences in composition between the two. Plasma consists of dissolved proteins, albumins, globulin, glucose, hormones, clotting factors etc. whereas, the serum is simply a plasma without fibrogens.
I believe the higher current recorded in plasma is solely due to the differences in the composition of the two.
Best of luck.
Hello Patricia Khashayar
I agree with Abubakar Abdussalam , the difference in composition between serum and plasma should be the main cause. With plasma your system might have a completely different conductivity. Have you tried EIS measurements? You could maybe investigate your system in more details.
Best regards,
Marie B.
Hi Patricia Khashayar ,
I agree with both of (Marie Berthuel and Abubakar Abdussalam ) them. My opinion is there are many antioxidants and peroxides present in the blood plasma which can collective interference while performing ferricyanide reaction. Please refer to the following work
Article An Electrochemical Apparatus for Determination of the Redox ...
That make sense but the problem is when we use whole blood we don't see this higher current. And the current is even higher than the bare baseline, could that also be explained by the composition only?
Hi Patricia Khashayar ,
I think concentration of EDTA must be the game player here. According to your statement "The DPV reading is the same when plasma and EDTA plasma is used." , the only difference is EDTA. Moreover EDTA can show influence in the redox peaks since EDTA can alter the electron exchange phenomenon, availing the electron exchange more facile. EDTA can be used for the electrochemical reaction to avoid the fouling of the electrode surface. Please refer the following paper.
Article Influence of EDTA on the electrochemical behavior of phenols
Hi Patricia,
You mentioned that when you used a 'whole blood' you didn't observe the higher current. I suggest that you study the selectivity of your biosensor in the presence of interferents that form the matrix. Once you do that you will be able to understand with utmost certainty which of the components affect the current and alter your result.
Thanks for your answers. Thats why we used pure plasma (without EDTA and separated using membrane) and EDTA plasma. Yes there is an extra peak when EDTA is in the solution congirming the effect of the EDTA on the redox reading. But still we were reading higher currents with even pure plasma
As for the matrix content, all of these material are present in while blood so i expected to read the same trend when using plasma and whole blood but this is not the case. With whole blood we have the reducing current similar to what we had with serum and thats confusing
Dear Patricia
I totally agree with all the previous answers and I think you may be need to do the normalization for your samples, I mean both (plasma and serum) by donig all the expermantal measurments of the samples firstly as a control test . I hope this note is useful for your question
Kind regards
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