Photoactivatable copolymers of vinylbenzyl thiocyanate as immobilization matrix for biochips

Biochip surfaces for immobilization of DNA and proteins require reactive polymers with high immobilization capacity and low nonspecific binding. Most reactive surfaces consist of matrixes that provide epoxy, aldehyde, or amino functions for biomolecule binding. The most widely used oligonucleotide modification is a C6-amino link. The high reactivity of isothiocyanate groups (NCS) toward amines was therefore the motivation to employ photogenerated NCS groups as binding sites for NH(2)-terminated oligonucleotides. 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 was approximately 80% at 450 mJ cm(-)(2) (lambda(ex) = 254 nm). This surface was superior to tested commercial chip surfaces in signal-to-noise-ratio and reproducibility. 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 patterning of biochips.