Optical spectroscopy on conjugated polymers and their interactions with DNA

Abstract

<P>IN THIS THESIS, WE PRESENT SOME OPTICAL SPECTROSCOPIC STUDIES ON CONJUGATED OLIGOMERS AND POLYMERS, CONJUGATED POLYMER-DNA INTERACTIONS, AND THEIR APPLICATIONS IN BIOSENSORS AND IMPLICATIONS IN PHOTOTHERAPY. ONE-PHOTON AND TWO-PHOTON ABSORPTION AND FLUORESCENCE, ONE-PHOTON AND TWO-PHOTON EXCITATION FORSTER RESONANCE ENERGY TRANSFER (FRET), HAVE BEEN USED IN OUR STUDIES. CONJUGATED POLYMERS CAN PROVIDE COLLECTIVE OPTICAL RESPONSE AND CAN BE USED TO DEVELOP BIOSENSORS WITH SIGNIFICANTLY IMPROVED SENSITIVITY. WE HAVE DEMONSTRATED A BIOSENSOR SCHEME USING CASCADING ENERGY TRANSFER FROM CONJUGATED POLYMERS TO A DNA INTERCALATOR VIA A FLUOROPHORE TETHERED TO THE END OF DNA. IN COMBINATION WITH DNA MELTING ANALYSIS, THIS METHOD CAN PROVIDE A SING-BASE MISMATCH CAPABILITY WITH ENHANCED SENSITIVITIES. WE HAVE ALSO DEMONSTRATED THAT CONJUGATED POLYMERS CAN INDUCE AGGREGATION OF DNA STRANDS AND THUS RESULT IN A COOPERATIVE QUENCHING EFFECT, WHICH CAN BE USED IN DNA ASSAY WITH EXCEPTIONALLY HI