Selective capture of human red blood cells based on blood group using long-range surface plasmon waveguides

An optical biosensor based on long-range surface plasmon-polariton waveguides is applied to the detection of blood group antigen A on whole erythrocytes. The biosensor consists of straight gold waveguides embedded in CYTOP with an etched fluidic channel. The gold waveguides were functionalized with immunoglobulin G against blood group A (anti-A IgG) by forming a self-assembled monolayer (SAM) of 16-mercaptohexadecanoic acid (16-MHA) and then conjugating the anti-A IgG through carbodiimide chemistry. In order to demonstrate anti-A surface selectivity, solutions of O-type, B-type, A-type and AB-type red blood cells (RBCs) were sequentially injected over an anti-A functionalized waveguide. Surfaces were regenerated by lysing attached cells with distilled/deionized water (DDI H2O). The efficiency of surface regeneration with DDI H2O was very high as determined by performing six sequential binding/regeneration cycles of A RBC capture on the same anti-A surface. Also, five solutions of different A RBC concentrations, ranging from 1.14 × 10(5)cells/ml to 1.83 × 10(6)cells/ml, were injected over an anti-A surface to determine the limit of detection (LOD), which was found to be less than 3 × 10(5)cells/ml. Finally, the response produced by a single cell bound to a waveguide was determined by relating the number of bound cells to the response produced, from which the signal-to-noise ratio for single cell detection was determined to be ~95. The waveguides are promising as simple, low-cost and compact transducers, functionalized using standard thiol-based chemistries, for the selective detection of cells.