An AFM study of the hierarchical DNA immobilization/hybridization processes on surfaces

Abstract

The immobilization and hybridization processes of DNA strands on poly-l-lysine (PL) covered surfaces have been studied using the atomic force microscopy (AFM) in a topographic mode. The statistical analysis of topographic surfaces showed an increase in the Z-threshold with additions of single strand DNA (ssDNA) and the complimentary DNA (ccDNA). Also no drastic change of statistical fractal dimension (slope of the log-log perimeter-area plot) is observed when comparing the PL-surfaces coated with ssDNA and ccDNA. These two results suggest that ssDNA strands are successfully immobilized and spatially hybridized with ccDNA on the PL surface and the growth of hybridized ccDNA occurs mainly in the vertical dimension. The methods described here are good candidates for the detection of DNA hybridization, especially in the context of DNA nanoarrays.