Screening of multiple hemoprotein-specific aptamers and their applications for the binding, quantification, and extraction of hemoproteins in a microfluidic system.

The blood hemoproteins, albumin, γ-globulin, and fibrinogen, serve as biomarkers for a variety of human diseases, including kidney and hepatorenal syndromes. Therefore, there is a need to quickly and accurately measure their concentrations in blood. Herein, nucleic acid aptamers demonstrating high affinity and specificity toward these hemoproteins were selected via systematic evolution of ligands by exponential enrichment, and their ability to capture their protein targets was assessed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by a tetramethyl benzidine assay. The limits of detection for the hemoproteins were all around 10-3 μM, and dissociation constant values of 131, 639, and 29nM were obtained; capture rates were measured to be 66%, 71%, and 61%, which is likely to be suitable for clinical diagnostics. Furthermore, a multi-layer microfluidic disk system featuring hemoprotein-specific aptamers for depleting hemoproteins was demonstrated. It could be a promising approach to use aptamers to replace conventional antibodies.