Thyroglobulin detection using competitive protein adsorption

We report a unique sensing mechanism based on competitive proteins' adsorption/exchange reaction, namely Vroman effect, for detecting a cancer biomarker, thyroglobulin (Tg). Implemented in a microfluidic system, the target protein, Tg, displaces a pre-adsorbed weak-affinity protein, IgG, on one surface, while a pre-adsorbed strong-affinity protein, fibrinogen, is not displaced by Tg on the other surface. Differential measurement using SPR (Surface Plasmon Resonance) allows the detection of Tg; the SPR angle changes offer a quantitative analysis of concentration of Tg in a sample. Using this technique, we demonstrate the selective detection of Tg in a protein mixture of albumin, haptoglobin, IgG and Tg.