Dendrislides, dendrichips: a simple chemical functionalization of glass slides with phosphorus dendrimers as an effective means for the preparation of biochips

Materials with tailored surface properties are useful for diverse applications, in particular for adsorption and/or covalent immobilization of various biomolecules such as nucleic acids and proteins. One of the main challenges is to design a reactive surface chemistry for stable binding of biomolecules on the support, which in addition keeps away the biomolecules from the support to reduce interference. We report here a novel support functionalization that is based on the formation of a reactive layer, covalently grafted on glass slides onto which amino-modified DNA probes were covalently fixed. The layer is composed of spherical home-made neutral phosphorus dendrimers containing a large number of aldehyde functions at their periphery. The method of preparation of these dendrimer-activated glass slides (so-called dendrislides) is performed in a few steps and results in stable activated supports, since aldehyde dendrimers are stable compounds. After immobilization of nucleic acids the so-called dendrichip products were investigated by means of hybridization experiments using complementary fluorescent labelled-oligonucleotide targets. Our results indicate that this novel grafting technology leads to surfaces with a high binding capacity for amino-modified oligonucleotides compared to commercially available aldehyde slides and with a detection limit of 1 pM labelled targets. Since links between the surface, the dendrimers and the nucleic acids are covalent, the dendrichips could be re-used up to 10 times without significant change in the fluorescence signal intensity. Finally, the performance of dendrichips in detection of a single base mutation was demonstrated.