Direct Measurement of Single-Molecule Diffusion and Photodecomposition in Free Solution

Abstract

Continuous monitoring of submillisecond free-solution dynamics of individual rhodamine-6G molecules and 30-base single-stranded DNA tagged with rhodamine was achieved. Fluorescence images were recorded from the same set of isolated molecules excited either through the evanescent field at the quartz-liquid interface or as a thin layer of solution defined by micron-sized wires, giving diffraction-limited resolution of inter-connected attoliter volume elements. The single-molecule diffusion coefficients were smaller and the unimolecular photodecomposition lifetimes were longer for the dye-DNA covalent complex as compared with those of the dye molecule itself. Unlike bulk studies, stochastic behavior was found for individual molecules of each type, and smaller diffusion coefficients were observed.

Optical Studies of Single Molecules at Room Temperature

“…The usefulness of similar experiments on membrane transport of biological systems cannot be underestimated. The diffusion trajectories of single dye molecules in a polymer matrix have also been recorded with near-field microscopy (55, 56), in polyacrylamide gels (22), and in solution with CCD cameras (57).…”

Self‐assembled organic nanotubes: Toward attoliter chemistry

“…To manipulate still ultrasmaller volumes of liquids in such diverse fields as cell biology, microfluidics, capillary chromatography, and nanolithography, one needs a better understanding of fluid behavior confined in attoliter volume. [1][2][3][4][5][6][7] Indeed, water in nanometer-sized restricted geometries, such as micelles and microemulsions, 8,9 nanometer films, 10,11 and nanoporous silica, 12 often shows different and sometimes unexpected features in comparison to bulk water. The trend of miniaturization in conventional microchip devices consisting of poly(dimethylsiloxane), silicone, and glass has thus directed growing attention to new femtoliter (fL ¼ 10 À15 L) or attoliter (aL ¼ 10 À18 L) vessels like carbon 13 and silica nanotubes.…”

Fluctuation-Induced Transitions in a Bistable Surface Reaction: Catalytic CO Oxidation on a Pt Field Emitter Tip

“…Mainly because of discrepancies from the predictions of macroscopic rate laws, noisy systems have attracted considerable theoretical interest [1][2][3]. There have also been experimental studies, e.g., of photosensitive reactions subject to external noise [2], and of intermittency in single-molecule spectroscopy studies [4], but few studies of the effect of fluctuations due to internal noise in nonlinear reaction-diffusion systems.…”