Concentration-enhanced rapid detection of human chorionic gonadotropin (hCG) on a Au surface using a nanofluidic preconcentrator.

Here, we report a new method of concentration-enhanced binding kinetics for a rapid immunoassay screening test on a gold surface in a poly(dimethylsiloxane) (PDMS) microfluidic chip format. The use of alkylthiolate self-assembled monolayers on gold surfaces of a PDMS-glass microchip resulted in accelerated binding kinetics of Human chorionic gonadotropin (hCG) at an electrokinetic trapping zone. We used a PBS solution (buffer concentration ~ 150 mM), not a dibasic buffer system (~10 mM), for the dynamic preconcentrating operation and the preconcentration of cy3 labeled streptavidin onto biotinylated Au surface revealed that the binding kinetics of the protein were linearly proportional to the concentration profile of the preconcentration plug. We showed rapid detection of hCG in the clinical range with a shorten assay time of 10 min. Also, we demonstrated that the amount of sample needed were detection was decreased from ~4 mL to ~25 μL in the standard serum tests. The enhanced binding kinetics between hcG Ag-Ab via preconcentration showed good feasibility for use in a rapid immunoassay screening test.