Simple one-step process for immobilization of biomolecules on polymer substrates based on surface-attached polymer networks.

For the miniaturization of biological assays, especially for the fabrication of microarrays, immobilization of biomolecules at the surfaces of the chips is the decisive factor. Accordingly, a variety of binding techniques have been developed over the years to immobilize DNA or proteins onto such substrates. Most of them require rather complex fabrication processes and sophisticated surface chemistry. Here, a comparatively simple immobilization technique is presented, which is based on the local generation of small spots of surface attached polymer networks. Immobilization is achieved in a one-step procedure: probe molecules are mixed with a photoactive copolymer in aqueous buffer, spotted onto a solid support, and cross-linked as well as bound to the substrate during brief flood exposure to UV light. The described procedure permits spatially confined surface functionalization and allows reliable binding of biological species to conventional substrates such as glass microscope slides as well as various types of plastic substrates with comparable performance. The latter also permits immobilization on structured, thermoformed substrates resulting in an all-plastic biochip platform, which is simple and cheap and seems to be promising for a variety of microdiagnostic applications.

Attachment of polymer films to solid surfaces via thermal activation of self-assembled monolayers containing sulphonyl azide group.

We report on a simple and effective way to attach thin polymer films to solid surfaces. The system is based on a thermosensitive sulphonyl azide derivative that is immobilized to SiO(2) surfaces via chlorosilane anchoring group and subsequently covered with a polymer film. Upon heating the sulfonyl azide decomposes, leading to a C-H insertion reaction from the adjacent polymer chain resulting in a covalent attachment of the polymer to the surface. Any nonbound polymer can be removed by extraction. The method allows to attach a wide spectrum of polymers to solid surfaces. The film thickness of the monolayers can be tuned by adjusting the molecular weight of the polymer used and to some extent, the thermolysis conditions. The film thickness increases linearly with the radius of gyration of the polymers used for attachment. We have successfully attached thin layers of poly (styrene), poly (dimethylacryl amide) and poly (heptadecafluorodecylacrylate).