Amino-containing cationic latex-oligodeoxyribonucleotide conjugates: application to diagnostic test sensitivity enhancement

The covalent immobilization of nucleic acid probes (ODN) onto amino-contain ing cationic hydrophobic (polystyrene) or hydrophilic poly(N-isopropylacryl amide) latexes has been investigated. A preliminary study was devoted to th e adsorption behavior of ODNs as a function of pH, ionic strength and type of latex. A drastic reduction of ODN adsorption upon increasing ionic stren gth was found, especially with hydrophilic-based latexes. Then, covalent at tachment of ODNs onto the reactive particles was performed in a basic pH(> 9) so as to avoid physical adsorption. Coating of the ODN-latex conjugates onto solid surfaces resulted in the formation of two dimensional assemblies . These functionalized surfaces were finally used for the detection of the HBV virus DNA, providing sensitivity improvement identical to what was alre ady observed with linear polymers. (C) 1999 Elsevier Science B.V. All right s reserved.