(Invited) Ultrasensitive Detection of Nucleic Acid Molecules with Interferometric Plasmonic Microscopy

Abstract

The detection of nucleic acid molecules plays important role in clinical diagnosis of diseases and fundamental biomedical research. The widely used polymerized chain reaction technique requires hours of amplification process, and is prone to aerosol pollution. Here, we presented the amplification-free digital sensing of nucleic acid molecules with the interferometric plasmonic microscopy (iPM). A sandwich assay was performed with the primary DNA probes coated on the plasmonic sensing surface and the secondary DNA probes tethered Au nanoparticles. Hybridization between DNA probes and single analyte molecules was monitored by the imaging of single Au nanoparticle with iPM system. By digitally counting the events of hybridization, the detection limit at the fM level could be achieved. Without amplification, this assay could be done within one hour. Furthermore, by analyzing the real-time binding behaviro during single hybridization event, non-specific bindings could be excluded from the specific ones, resulting in the improved specificity. This technique could be further improving by a careful design of the kinetic binding properties between DNA probes and analyte molecules.