Single-Molecule Observations of Giant DNA and Synthetic Polyelectrolyte by Labeling with Semiconductor "Quantum Dots"

Semiconductors nanoparticles (quantum dots) possess outstanding optical properties compared to conventional organic fluorescent dyes. At present, quantum dots are widely used for observation of cells and tissues, labeling short oligonucleotide sequences for detection of oligonucleotide hybridization, and other biological purposes. On the other hand, labeling of long polyelectrolytes including genome DNAs with quantum dots has not been examined yet. In this report we present results of our investigation on long DNA molecules and long synthetic polyelectrolyte (sodium polysterenesulfonate) labeling by commercially available quantum dots (Qdots^reg, Invitrogen, USA) as a first protocol for quantum dot based single molecule observation of long polymer chains. We optimized experimental conditions for observation of single-molecule DNA and sodium polystyrene sulfonate chain performed comparative analysis of the possibility to use Qdots for tracking DNA and polyelectrolyte conformational transitions such as "coil-globule" transition.