Real-Time Monitoring of Ligand Binding to G-Quadruplex and Duplex DNA by Whispering Gallery Mode Sensing

Abstract

The therapeutic potential of small molecules targeting G-quadruplexes has gained credibility since such structures were shown to form in human cells and to be highly prevalent in the human genome, most notably at telomere ends and in oncogene promoters. Herein, we perform whispering gallery mode (WGM) sensing for monitoring DNA–small molecule interactions. Unlike most existing technologies, WGM sensing offers numerous advantages including high sensitivity, real-time analysis, easy access to kinetic parameters, and much lower cost than current gold standards. In this work, interactions of five known DNA-binding ligands with either G-quadruplex or duplex DNA immobilized on a sphere microresonator have been assessed. The induced shift of the resonant mode from quadruplex (or duplex)–ligand binding was used to estimate kinetic parameters. Association and dissociation rate constants (kon and koff, respectively) as well as dissociation equilibrium constants (KD) were measured for these five ligands binding to both duplex and quadruplex DNA

Development of microfluidic platforms for the synthesis of metal complexes and evaluation of their DNA affinity using online FRET melting assays

“…There have also been some reports where microfluidic platforms have exploited the interaction between G4 DNA and an optical probe for sensing, as well as examples where microfluidic platforms have been used to assess G4 DNA–ligand interactions. 45 , 46 …”

Miniature temperature sensor based on encapsulated silica microfibre–microsphere structure

“…By filling the columnar magnetic fluid particles into the photonic crystal fibre to simulate WGM, a real-time magnetic detector was demonstrated with a sensitivity of 110 pm/mT [15]. The unlabelled, highly sensitive and real-time biosensors based on WGM effect have been explored to monitor the biological activity of small molecules, such as viruses and DNA [16] and enhance their selectivity by specific decoration [17]. In this Letter, we used the common single-mode optical fibre (SMF) to fabricate the silica microspheres with different diameters and constructed the WGM system based on silica microsphere and microfibre.…”