Immobilization of oligonucleotides onto indium tin oxide surfaces using a zirconium coupling

Biosensors and microarrays that detect biological binding events such as DNA hybridization often involve the use of surface-immobilized probe molecules. The interfacial behavior can be substantially different from that observed in bulk solution, and depends on the physical environment near the surface. An electrically conductive material that is also transparent would be an interesting platform for the control of the interface, and the concurrent detection of binding events by means of optical interrogation. This report describes a method for immobilization of oligonucleotides onto indium tin oxide (ITO) films that are coated on glass slides. The immobilization is based on the reaction of Zr(IV) with ITO, followed by treatment with sodium sulfate, or by attachment of an organic moiety. Pre-synthesized oligonucleotides modified with an aliphatic carbon chain and a primary amine group at the end of the chain were immobilized. The immobilized probes showed fluorescence signals for repeated cycles of hybridization/denaturization, and demonstrated high thermal stability with hybridization remaining constant in some cases even after heating at 95degreesC for over six hours.