My research is focused on the development of an electrochemical paper based biosensor that is capable of blood plasma separation and the following quantification of proteins released into the bloodstream when traumatic brain injury occurs. I am currently developing the first part of the device following the protocol designed by Noiphung et al (2013, https://www.ncbi.nlm.nih.gov/pubmed/23845479) which uses the wax printing method for creating hydrophilic channels where plasma is obtained from whole blood by means of capillary action. However, having done a literature review, Kersaudy et al. (2013, https://www.ncbi.nlm.nih.gov/pubmed/23824514) mentioned this: “While paper can be used conveniently to separate several microliters of blood such as finger-prick volumes, it rapidly clogs and is unsuitable for larger volumes, limiting its use to the analysis of highly concentrated analytes, such as glucose or abundant proteins". The problem lies in the fact that the proteins I want to detect have an average concentration in serum of 0.3pg/mL and with my paper microfluidic device I could obtain a maximum of 100 microliters of plasma in the detection zone. Since the electrochemical essay comprises an antigen-antibody binding, I am not sure whether I will be able to achieve a detection limit low enough to detect the average protein concentration of 0.3pg/mL. Hence, I would like to know if someone is currently working on a problem such as the one I am currently facing.
I appreciate in advance your help. All suggestion are welcome.
Sincerely,
Francisco Burgos
Please see Vivid blood separation membranes sold by Pall Life Sciences: https://shop.pall.com/us/en/medical/advanced-materials/diagnostics/vivid-plasma-separation-membrane-zidgri78lls
We were facing the same issue (achieving the low limit of detectionto by lateral flow assay). As we couldn’t solve it, we changed the approach to another method as of now.
Based on my limited knowledg, to achieve low limit of detection, you have to find an approach which is robust in detection of your analyte with regards to its molecular size e.g direct vs indirect immunoassay, enzymatic vs fluorometric, etc. (I chose competetive fluoro-based immunoassay).
Besides, you can think of amplifying either the detected signal or the analyte (i.e. your protein). For the first approach, you can concentrate your analyte in a n much smaller region. For the second approach, you can use a PCR (e.g. can integrate paper-based PCR into your current kit) to amplify the analye for easier detection.
Francisco Javier Burgos Flórez , you may want to limit the concentration of the antibody to minimize the Hook effect
https://en.wikipedia.org/wiki/Hook_effect
Excess antibody and/or antigen could mask the signal upon binding..
Also, please be aware of the matrix effect caused by plasma proteins..
Article Matrix effects and selectivity issues in LC-MS-MS
The Vivid blood-plasma separation suggested by Constantine Anagnostopoulos Sir is a good choice for on-chip blood-plasma separation
Thank you all for your comments, suggestions and recommendations. They have all been really helpful and enlightening.
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