Real-Time Study of the Interaction between G-Rich DNA Oligonucleotides and Lead Ion on DNA Tetrahedron-Functionalized Sensing Platform by Dual Polarization Interferometry

G-quadruplex plays roles in numerous physiological and pathological processes of organisms. Due to the unique structure of G-quadruplex, it has been extensively used for the target detection including metal ions, low-weight molecules, DNAs, proteins, enzyme activities and even cells. But the formation process of G-quadruplex is rarely studied. Here, a DNA tetrahedron platform with higher reproducibility, regenerative ability, and time-saving building process was coupled with dual polarization interferometry (DPI) technique for the real-time and label-free investigating the specific recognition process of guanine-rich singled-stranded DNA (G-rich ssDNA) for Pb2+. The oriented immobilization of probes greatly decreased the spatial hindrance effect and improved the accessibility of the probes to the Pb2+ ions. Through the real-time monitoring the whole formation process of the G-quadruplex, we speculated the probes on the tetrahedron platform initially stood on the sensing surface with a random coil conforma...