Time-resolved energy transfer in DNA sequence detection using water-soluble conjugated polymers: the role of electrostatic and hydrophobic interactions.
We have investigated the energy transfer processes in DNA sequence detection by using cationic conjugated polymers and peptide nucleic acid (PNA) probes with ultrafast pump-dump-emission spectroscopy. Pump-dump-emission spectroscopy provides femtosecond temporal resolution and high sensitivity and avoids interference from the solvent response. The energy transfer from donor (the conjugated polymer) to acceptor (a fluorescent molecule attached to a PNA terminus) has been time resolved. The results indicate that both electrostatic and hydrophobic interactions contribute to the formation of cationic conjugated polymers/PNA-C/DNA complexes. The two interactions result in two different binding conformations. This picture is supported by the average donor-acceptor separations as estimated from time-resolved and steady-state measurements. Electrostatic interactions dominate at low concentrations and in mixed solvents.
Institute for Polymers and Organic Solids and Department of Chemistry and Materials, University of California, Santa Barbara, CA 93106, USA.
Qing-Hua
QH
Xu
Brent S
BS
Gaylord
Shu
S
Wang
Guillermo C
GC
Bazan
Daniel
D
Moses
Alan J
AJ
Heeger
D001483:Base Sequence; D015374:Biosensing Techniques / Q000379:methods*; D004247:DNA / Q000032:analysis*; D004735:Energy Transfer; D005456:Fluorescent Dyes; D057927:Hydrophobic and Hydrophilic Interactions; D020135:Peptide Nucleic Acids / Q000737:chemistry; D011108:Polymers / Q000737:chemistry; D013057:Spectrum Analysis; D055672:Static Electricity; D013997:Time Factors
D005456:Fluorescent Dyes; D020135:Peptide Nucleic Acids; D011108:Polymers; D004247:DNA