Single-molecule analysis of DNA immobilized on microspheres.

Abstract:: The formation and analysis of single molecules of fluorescently labeled DNA immobilized on polystyrene microspheres is described. Analysis by confocal fluorescence microscopy revealed single-step photobleaching, characteristic of a single fluorophore. Microspheres provide a means of locating single molecules by bright-field microscopy, prior to single-molecule detection. This allows the interrogation of single molecules without suffering the limitations of premature photobleaching. Statistical analysis of fluorescence intensities for >100 microspheres suggests attachment of DNA to micropsheres to be consistent with Poisson statistics.

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