Characterization of a polymeric adsorbed coating for DNA microarray glass slides

A new method was developed to covalently attach target
molecules onto the surface of glass substrates such as
microwell plates, beads, tubes, and microscope slides,
for hybridization assays with fluorescent targets. The
innovative concept introduced by this work is to physically
adsorb onto underivatized glass surfaces a functional
copolymer, able to graft amino-modified DNA molecules.
The polymer, obtained by radical copolymerization of N,Ndimethylacrylamide,
N-acryloyloxysuccinimide, and 3-(trimethoxysilyl)
propyl methacrylate, copoly(DMA-NASMAPS),
self-adsorbs onto the glass surface very quickly,
typically in 5-30 min. The film, formed on the surface,
bears active esters, which react with amino-modified DNA
targets. The surface layer is stable in an aqueous buffer
containing various additives (SDS, urea, salt), even at
boiling temperature. It should be emphasized that the
coating is formed by the immersion of glass slides in a
diluted aqueous solution of the polymer. Therefore, the
procedure is fast, inexpensive, robust, and reliable, and
it does not require time-consuming glass pretreatments.
Slides, coated with copoly(DMA-NAS-MAPS), were profitably
used as substrates for the preparation of low-density
DNA microarrays. The density and the thickness of the
films were evaluated by X-ray reflectivity measurements
whereas the extent of reaction of functional groups with
DNA molecules was determined by a functional test. The
experiments indicate that half of the active groups present
on the surface reacts with oligonucleotide probes.