Steady state and time resolved spectroscopic study of QD–DNA interaction

Here, we report the preparation of bioconjugates between cationic polymer functionalized green emitting CdTe quantum dot (QD) and ethidium bromide (EB) intercalated double stranded DNA (dsDNA). Water soluble, high quantum yield of CdTe QDs have been prepared by one pot synthesis. Cationic polymer (CP) is being used for surface modification of QD to obtain strong electrostatic interaction with EB intercalated dsDNA. It is found that the energy transfer (41%) takes place between CP modified QD and EB dye and the measured distance between donor and acceptor is found to be 35.7 Å which is close to the estimated distance. Analysis suggests that cationic polymer prevents denaturation, condensation or other conformational change of biomolecules in QD conjugated DNA system.