Electropolymerized polytyramine films: Covalent binding of oligonucleotides and hybridization

The electrooxidation of 4-hydroxyphenylethylamine (tyramine) in perchloric acid gives films presenting one reactive amine group per moiety. Poly(tyramine) (PTyr) film structure was determined by several techniques (SEM, EQCM, XPS, FT-IR). Oligonucleotides bearing a phosphate terminal function were immobilised on these reactive PTyr films via a phosphoramidate covalent bond, yielding a high surface ODN concentration (up to 500 pmol.cm -2 ). A washing protocol was set up to discriminate adsorption from real covalent grafting. Preliminary measurements showed a high hybridization capacity of probes-modified PTyr films with good discrimination properties between native and mismatches containing sequences.