Surface Preparation for Single-Molecule Fluorescence Imaging in Organic Solvents

Area of Science:

• Physical Chemistry
• Chemical Imaging
• Surface Science

Background:

• Single-molecule techniques offer unique insights into molecular properties and heterogeneities not observable in ensemble measurements.
• Single-molecule fluorescence microscopy is increasingly used for studying chemical reactions in organic solvents.
• Optimization of surface preparation for single-molecule fluorescence imaging in organic solvents remains underexplored.

Purpose of the Study:

• To develop and optimize a surface preparation method for single-molecule fluorescence imaging in organic solvents.
• To achieve well-controlled surface density of chemically immobilized dye molecules.
• To minimize nonspecific adsorption of impurities for enhanced imaging quality.

Main Methods:

• Developed a novel surface preparation procedure for single-molecule fluorescence imaging.
• Compared two distinct surface preparation protocols.
• Investigated the influence of solvent polarity and surface functionality on surface quality.
• Performed single-molecule fluorescence imaging in N,N-Dimethylformamide (DMF).

Main Results:

• The developed method achieved a well-controlled surface density of chemically immobilized dye molecules.
• Higher polarities of both solvent and surface functionality led to better control over dye immobilization and reduced nonspecific adsorption.
• Identified and characterized photophysical properties of dyes and fluorescent impurities in DMF.
• Established a method to filter out false counts in single-molecule fluorescence measurements.

Conclusions:

• The optimized surface preparation method significantly enhances the quality of single-molecule fluorescence imaging in organic solvents.
• Polarity plays a crucial role in controlling surface density and minimizing background noise.
• Understanding dye and impurity photophysics aids in accurate data interpretation for chemical reaction studies.