Human T-cell lymphotropic virus type 1 nucleocapsid protein-induced structural changes in transactivation response DNA hairpin measured by single-molecule fluorescence resonance energy transfer.

Time-resolved single-molecule fluorescence spectroscopy was used to study the human T-cell lymphotropic virus type 1 (HTLV-1) nucleocapsid protein (NC) chaperone activity compared to that of the human immunodeficiency virus type 1 (HIV-1) NC protein. HTLV-1 NC contains two zinc fingers, each having a CCHC binding motif similar to HIV-1 NC. HIV-1 NC is required for recognition and packaging of the viral RNA and is also a nucleic acid chaperone protein that facilitates nucleic acid restructuring during reverse transcription.

Single ion diffusive transport within a Poly(styrene sulfonate) polymer brush matrix probed by fluorescence correlation spectroscopy.

Diffusive transport within complex environments is a critical piece of the chemistry occurring in such diverse membrane systems as proton exchange and bilayer lipid membranes. In the present study, fluorescence correlation spectroscopy was used to evaluate diffusive charge transport within a strong polyelectrolyte polymer brush. The fluorescent cation rhodamine-6G was used as a counterion probe molecule, and the strong polyelectrolyte poly(styrene sulfonate) was the polymer brush.

Dynamics of an anti-VEGF DNA aptamer: a single-molecule study.

Single-molecule fluorescence resonance energy transfer (SMFRET) was used to study the interaction of a 25-nucleotide (nt) DNA aptamer with its binding target, vascular endothelial growth factor (VEGF). Conformational dynamics of the aptamer were studied in the absence of VEGF in order to characterize fluctuations in the unbound nucleic acid. SMFRET efficiency distributions showed that, while the aptamer favors a base-paired conformation, there are frequent conversions to higher energy conformations.

Size-dependent ultrafast electronic energy relaxation and enhanced fluorescence of copper nanoparticles.

The energy relaxation of the electrons in the conduction band of 12 and 30 nm diameter copper nanoparticles in colloidal solution was investigated using femtosecond time-resolved transient spectroscopy. Experimental results show that the hot electron energy relaxation is faster in 12 nm copper nanoparticles (0.37 ps) than that in 30 nm copper nanoparticles (0.