Simple surface chemistry to immobilize DNA probes that significantly increases sensitivity and spots density of surface plasmon resonance imaging based microarray systems

SPRi technology is a promising method for label-free detection and quantification of biomolecules interactions. In this present work, we present huge advance in multiplexing and reduction of the detection limit of SPRi technology, considering DNA interactions. We have used without electrodeposition an alternative chemistry for direct deposition of oligonucleotide probes on gold surface by using thiol-modified oligonucleotide probes. This immobilization of DNA probes is extremely efficient, reproducible and easy to implement. In addition we increased the spotting density up to 1000 spots, using commercial spotters dedicated to high-density microarrays. Increasing the roughness of the gold surface with gold nanoparticles prior to probe attachment, we amplified the optical signal of SPR by a factor 3 enabling the detection of DNA targets at concentrations as low as 2 nM. Finally, all these improvements make very attractive and competitive the SPRi technology.