Poly( l-lysine)-mediated immobilisation of oligonucleotides on carboxy-rich polymer surfaces

Abstract

The immobilisation efficiency of the complexes of oligonucleotide/poly( l-lysine) on two polymeric carboxy-rich surfaces, i.e. poly(styrene/maleic acid) (PSMA) and poly(styrene/maleic anhydride) (PSMAA), has been investigated using X-ray photoelectron spectroscopy, atomic force microscopy (AFM) and fluorescence-based measurements of DNA attachment. A molecularly thin layer of either electrostatically or covalently (via amide bond) bound poly( l-lysine) allows the ‘switching’ from COOH-based to NH 2-based surface functionality. The results indicate that approximately 54–57% and 55–62% of the applied oligonucleotides bind to polymeric surfaces via the route of electrostatic adsorption of poly( l-lysine) and covalent bonding of poly( l-lysine), respectively. This system can be applied conveniently for the detection of nucleic acids in both disposable and reusable biosensors.