Photoactivatable copolymers of vinilbenzylthiocyanate as immobilization matrix for biochips

Biochip surfaces for immobilization of DNA and proteins require reactive polymers with high immobilization capacity and low non-specific binding.Most reactive surfaces consist of matrices which provide epoxy-, dldehyde-, or amino-functions for biomolecule binding. The most widely used oligonucleotide modification is a C6-amino link. The high reactivity of isothiocyanate groups (-NCS)towards amines was therefore the motivation to employ photogenerated NCS groups as binding sites for NH2-terminated oligonuclotides. Photosensitive poly(styrene-co-4-vinylbenzyl thiocyanate) (PST-co-VBT)was synthesized and applied as novel material for DNA- and protein immobilization. The immobilization capacity of PST-co-Vbt was a function of UV energy density used for photoactivation and wasabout 80% at 450mJ cm2 (ex=254 nm).This surface was superior to tested commercial chip surfaces in sensitivity and signal-to-noise-ratio. Print buffer and spacer length were optimized for maximum fluorescence signal with DNA and proteins. UV-exposure conditions and oligonucleotide modification were correlated showing that this photochemical approach can be successfully applied for surface patterningof biochips