Toward Nanoscale Imaging of Biomolecular Systems

COFFEE_KLATCH · Invited

Abstract

Biological cells fabricate and assemble molecular building blocks into diverse molecular networks with striking complexity and functionality. As such, they are model integrated nanosystems whose study should yield important information for optimizing specific cellular functions, and for engineering functional synthetic nano-systems. To study biological systems in this context, it is crucial to observe their molecular machinery at work in a physiologically relevant environment. Currently, there are no techniques that can accomplish this.To study these systems at the molecular length scale, we have developed a near-field microscopy technique called tip-enhanced fluorescence microscopy (TEFM) that combines tapping-mode atomic force microscopy (AFM) with confocal fluorescence microscopy. Briefly, a strong axial field is produced at the focus of a laser beam and an AFM probe is positioned into the focus. This creates a localized dipole field at the tip apex, which can strongly excite fluorescence of nearby chromophores. Scanning the illuminated tip over a surface leads to high-fidelity fluorescence images with resolution limited only by the sharpness of the tip. In contrast to AFM, TEFM also provides single-molecule sensitivity and biochemical specificity when combined with fluorescence labeling. We recently demonstrated $\sim$10 nm resolution in TEFM images of quantum dots in air and we are now working to extend its capabilities to liquid imaging and to improve the resolution yet further by attaching carbon nanotubes to the ends of the AFM tips.

–

Authors

  • Stanley C. Solomon

    University of California and Lawrence Berkeley National Laboratory, Rutgers University, Utah State University, Brigham Young University, University of Utah, NASA, Duke University, FMA Research, Colorado State University, Dartmouth University, Idaho State University, Physics Department, Idaho State University, Physics Department, Utah State University, Los Alamos National Laboratory, Department of Physics, Nanjing University, China, University of California at Riverside, Physics Department, Colorado School of Mines, Physics Department, University of Utah, University of Nebraska - Lincoln, USU, Society of Physics Students, Arizona State University, Institute for Materials Science (NIMS), Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan, LANSCE-LC, Los Alamos National Laboratory, Van der Waals-Zeeman Institute, University of Amsterdam, Chemistry and Physics Dept., Virginia State University, University of Saskatchewan, Canada, Chalk River Laboratories, Physics Dept, Oxford University, Physics Dept, Utah State University, Sandia National Laboratories, National Renewable Energy Laboratory, DOE Center for Integrated Nanotechnologies, Sandia National Laboratories, National Center for Atmospheric Research