Layer-by-layer deposition of functional click polymers for microarray applications

Bioprobes immobilization methods that elevate the probes from the substrate are generally preferred in microarray technology because they prevent steric limitations during the hybridization of the target to probes. A versatile approach to control the thickness of a polymeric coating based on click chemistry to obtain covalently linked layer-by-layer coatings for surface functionalization is presented. By alternating cycles of coating using copolymers bearing click groups, the thickness of the film increases, while remaining functional and stable. Click chemistry reactions provide numerous advantages over standard conjugation procedures typically used in microarrays. They include: quantitative yields and insensitivity of the reaction to pH and hydrolysis. Moreover, click reactions do not interfere with organic groups naturally present in DNA, proteins and peptides such as amino and carboxyl groups allowing orthogonal and chemoselective probe immobilization. In addition to the formation of multilayers, click reactions allow to bind biomolecules to polymer chains generating so-called polymeric probes, which are then immobilized on microarray supports. In a microarray assay of clinical relevance, this methodology provides a miniaturized, tri-dimensional multilayer with higher density of capture probe, improved hybridization efficiency and sensitivity.