EVALUATION OF THERMODYNAMIC AND PHOTOPHYSICAL PROPERTIES OF TRICARBOCYANINE NEAR-IR DYES IN ORGANIZED MEDIA USING SINGLE-MOLECULE MONITORING

Detection of single NIR fluorescent dye molecules in the organized med ia sodium dodecyl sulfate (SDS) and triton X-100 surfactants above the ir critical micelle concentrations was used to determine partition coe fficients and photophysical properties of dye molecules resident withi n the micelle aggregate. Inspection of the filtered data showed eviden ce of large amplitude photon bursts arising from single molecular even ts in these organized media. In pure H2O containing dye, no bursts wer e observed. The results indicate that only molecules resident within t he hydrophobic core of the micelle were detected. From the number of e vents observed and the number of events expected, partition coefficien ts (K-p) for IR-132 in SDS and triton X-100 solutions were calculated. In addition, the photon yield per molecule associated with only those molecules resident within the hydrophobic cavity of the micelle was d etermined.