Observation of microarray DNA hybridization using surface plasmon resonance phase-shift interferometry

Surface plasmon resonance phase-shift interferometry (SPR-PSI) is a novel technique which combines SPR and modified Mach-Zehnder phase-shifting interferometry to measure the spatial phase variation caused by biomolecular interactions upon a sensing chip. The SPR-PSI imaging system offers high resolution and high-throughout screening capabilities for microarray DNA hybridization without the need for additional labeling, and provides valuable real-time quantitative information. Current SPR-PSI imaging systems measure the spatial phase variation caused by tiny biomolecular changes on the sensing interface by means of a five-step phase reconstruction algorithm and a novel multichannel least mean squares (MLMS) phase unwrapping algorithm. The SPR-PSI imaging system has an enhanced detection limit of 2.5 × 10 -7 refraction index change, a long-term phase stability of π/100 in 30 minutes, and a spatial phase resolution of π/500 with a lateral resolution of 10μm. This study successfully demonstrates the kinetic and label-free observation of 5-mer DNA microarray hybridization.