Characterization of superlighting polymer-DNA aggregates:: A fluorescence and light scattering study

The massive amplification of fluorescence signal observed upon hybridization of as few as five DNA molecules into self-assembled structures formed between a cationic polymer and DNA oligonucleotides is investigated. These superlighting polymer-DNA aggregates were studied by fluorescence spectroscopy, static and dynamic light scattering, and zeta potential measurements in order to characterize the aggregation behavior and to understand the processes involved during DNA detection. Multi-angle laser light scattering was also used to obtain the weight-average aggregate mass (A(M)), the aggregation number (N-agg), the radius of gyration (R-g), and the dissymmetry ratio (z). These results have been used, together with TEM imaging, to propose a suitable physical model for the aggregates.