DNA-DNA interaction on dendron-functionalized sol-gel silica films followed with surface plasmon fluorescence spectroscopy.

Since we observed that dendron-assembled surface provided high single nucleotide polymorphism discrimination efficiency for DNA microarrays, and that the binding yield for streptavidin increased when biotin was immobilized on top of it, the nanoscale-controlled surface is examined for surface plasmon field-enhanced fluorescence spectroscopy (or SPFS). Firstly, a silica film was coated onto a gold substrate using the sol-gel technique, followed by the covalent immobilization of a layer of second-generation dendrons with a DNA catcher strand at their apex. The thickness of the inorganic interlayer (d=33 nm) was effectively suppressing fluorescence quenching. Thus, the kinetics and affinity characteristics of DNA hybridization could be investigated very sensitively by SPFS. The kinetic rate constants found for DNA hybridization on the dendron-modified surface were larger than those reported for a streptavidin-modified surface by one order of magnitude, except for dissociation rate constant for a single mismatched case. In addition, we observed that the DNA on the cone-shaped linker maintained its capability to capture DNA target strands even after extended storage at ambient conditions.