DETERMINATION OF SINGLE-STRANDED DNA THROUGH ITS HYBRIDIZATION WITH COMPLEMENTARY PROBES COUPLED ON THE SURFACES OF CARBOXYLATE POLYSTYRENE SPHERES

Abstract

A sensitive assay of single-stranded DNA in samples, labeled with a Texas Red (Tex) on its 5′-terminus, was proposed through hybridization interaction with its complementary probes coupled on the surfaces of carboxylate polystyrene spheres of 10-μm in diameter. In a phosphorus buffer solution (pH 6.8) of ionic strength higher than 0.15 mol/L, the hybridization interaction of the complementary DNA samples with the 20-mer DNA probes connected on the surfaces of polystyrene spheres can reach equilibrium about 55 min, and follows a second order reaction with the hybridization constant being 10³ levels. Samples of complementary DNA in the range of 0.5–4.0 × 10⁻⁹ mol/L can be detected with the limit of determination 4.8 × 10⁻¹⁰ mol/L (3σ), but more useful linear range is 4.0–16.0 × 10⁻⁹ mol/L, which can be expressed with the linear regression equation of ΔF = −9.1+ 2.5 × 10⁹ c _DNA-Tex (r = 0.9982).

Keywords:

• DNA
• Hybridization
• Carboxylate polystyrene spheres

ACKNOWLEDGMENTS

This program received the financial supports of the Natural Science Foundation of China (NSFC, No: 20045002), Subsidizing Program for Chinese University Core Teachers under the Education Ministry of China (No: 20000-65-2084), and the Application Basis Research Program of Municipal Science Committee of Chongiqng (China). All authors here express their deep thanks.