Amino-functionalized plasma polymer films for DNA immobilization and hybridization

DNA attachment on amine functionalized surfaces has been found to depend on the macromolecular architecture of the plasma films, on the amine group density as well as on the immobilization conditions. Surface Plasmon Resonance spectroscopy (SPR) and Surface Plasmon Enhanced Fluorescence Spectroscopy (SPFS) were used to monitor (a) the immobilization of probe oligomers (25 mers) to plasma polymerised allylamine films (ppA) and (b) their subsequent hybridization reactions with fluorophore-labeled 15 mer target oligonucleotides from solution. To avoid unspecific adsorption of target DNA, any unreacted amino groups were neutralized with succinic anhydride according to standard hybridization procedures. SPF spectroscopic investigations allowed for a precise differentiation between hybridization reactions with mismatch 2 (MM2), mismatch 1 (MM1) and fully complementary (MM0) oligonucleotide target sequences. Complementary target DNA hybridization was shown to have a significantly higher affinity constant (KA) than MM1 and MM2. Low energy plasma deposited allylamine films appear to act as a 3D matrix showing a high capacity towards DNA immobilization and hybridization reactions.