A current challenge regarding microfluidic paper-based analytical devices (µPAD) for blood plasma separation (BPS) and electrochemical immunodetection of protein biomarkers is how to achieve a µPAD that yields enough plasma to retain the biomarker for affinity biosensing in a functionalized electrode system. This paper describes the development of a BPS µPAD to detect and quantify the S100B biomarker from peripheral whole blood. The device uses NaCl functionalized VF2 filter paper as a sample collection pad, an MF1 filter paper for plasma retention, and an optimized microfluidic channel geometry. An inverted light microscope, scanning electron microscope (SEM), and image processing software were used for visualizing BPS efficiency. A design of experiments (DOE) assessed the device's efficacy using an S100B ELISA Kit to measure clinically relevant S100B concentrations in plasma. The BPS device obtained 50 μL of plasma from 300 μL of whole blood after 3.5 min. The statistical correlation of S100B concentrations obtained using plasma from standard centrifugation and the BPS device was 0.98. The BPS device provides a simple manufacturing protocol, short fabrication time, and is capable of S100B detection using ELISA, making one step towards the integration of technologies aimed at low-cost POC testing of clinically relevant biomarkers.
Keywords: ELISA; TBI biomarkers; blood plasma separation; microfluidics; paper.