Surface with poly-cationic polymers and functionalized using coupling chemistry, biosensor comprising the same and use thereof in bio-sensing

The invention relates to a surface functionalized with a poly-L-lysine polymer provided with oligo-ethylene glycol moieties, which are in turn partly modified with a functional moiety. In addition, the invention relates to said functionalized surface, wherein the surface is provided with exposed receptor molecules for binding to an analyte in e.g. a complex biological sample. More specifically, the invention relates to a functionalized surface for use in e.g. a biosensor for sensing (bio)molecules in e.g. a biological fluid or a solution comprising a biomarker, wherein the functionalized surface comprises poly-L-lysine polymer adhered thereto, said poly-L-lysine in part modified with oligo-ethylene glycol moieties which carry functional groups capable of specifically binding to the biomarker, i.e. receptor molecules for binding to an analyte. In addition, the invention relates to a method for providing such a functionalized surface and to the use of the functionalized surface as a binding partner for the biomarker. More specifically, the functionalized surface is for example suitable for binding cDNA from a complex mixture such as a biological sample.