Nucleic Acid Hybridization Enhanced Luminescence for Rapid and Sensitive RNA and DNA Based Diagnostics

Long-lived emissive nucleic acid probes are widely used in biochemical analysis due to their programmable structures, high signal-to-background ratio, and high sensitivity. Homogeneous detection based on long-lived emissive nucleic acid probes is often achieved through Förster resonance energy transfer (FRET), which suffers from the limitation of a narrow effective distance range. Herein, a new strategy of accessing nucleic acid hybridization-responsive luminescent probes is presented. The photoluminescence (PL) of a Lumi4-Tb complex internally modified with DNA is switched on by nucleic acid hybridization, after which the PL is increased up to 20 times. PL lifetime analysis revealed a possible mechanism of luminescence enhancement. Due to the flexibility of single-stranded nucleic acid chains, the bases and phosphate groups can coordinate with the Tb(III), which reduces the stability of the Tb complex and results in weak PL. After hybridization, the rigid double helix structure suppresses the coordination between Tb(III) and the bases or phosphate groups, causing luminescence enhancement. As the DNA sequence can be freely designed, an array of probes for different DNA or RNA targets can be created with the same Tb complex. Moreover, the novel probe design can afford pM detection limits of DNA or RNA without any nucleic acid amplification and exhibits great potential for nucleic acid detection in clinical diagnosis.