Sensitive DNA hybridization detection based on the deposition of gold nanoparticle on lyophobic surface

An assay for the detection of DNA hybridization was developed using Ellipsometric Scanner (ES) as a detection method. The different deposition trends of Au nanoparticle on glutaraldehyde-covered Si substrate caused by the different electrostatic properties of Au nanoparticles after interaction with ssDNA and dsDNA respectively can be observed by measuring the ellipsometric parameter y. At the same time, the average height of the y with respect to the cross-sectional contour c can be described by y = 0.0920 + 2.43c in the range of 5.4 to 27 nM (r = 0.943, c is target concentration, the unit is μM). This assay using ES imaging could successfully detect the total amounts of the target as low as 5.4 fmol. The proposed assay system has the advantage of allowing label-free detection, high sensitivity, and operational simplicity.