Gold glyconanoparticle-based colorimetric bioassay for the determination of glucose in human serum

Gold nanoparticles (d=10 nm) self-assembled with a specifically synthesized thiol-derivatized mannose were used to develop a novel colorimetric bioassay for glucose in human serum. The addition of Con A containing four binding sites induces the aggregation of mannose-stabilized gold nanoparticles via specific mannose-Con A interactions, which leads to a red shift of the surface plasmon absorption band centered at 520. nm. The presence of glucose in the solution hinders the Con A-induced aggregation of the mannose-stabilized gold nanoparticles because of the competitive binding of glucose to Con A. Thus, it results in a decrease of the surface plasmon absorption band shift. The simple surface plasmon absorption band change resulting from this method provides a selective means to detect and quantitate glucose in the linear concentration range of 500-4000μg/mL within 10. min with an experimental detection limit of 363μg/mL. The colorimetric assay was applied for the determination of glucose in human serum samples and the determined concentration was close to the value reported by the manufacturer of human serum sample used in the present experiment. The present bioassay can be successfully applied for the determination of human blood glucose levels for the diagnosis of diabetes without the use of enzymes.