| Atomic force microscopy (AFM) is an important tool for characterizing surfaces and intermolecular forces because of its imaging and force sensing capabilities in vacuum, ambient condition, and liquid. In this thesis, we present our efforts towards the creation of high-resolution AFM probes with carbon nanotubes and their applications to chemistry and biology.; We present our efforts towards the creation of carbon nanotube AFM probes. Four reproducible methods for fabrication of carbon nanotube tips are discussed: (1) Mechanical mounting of nanotubes. (2) Pore directed growth of nanotube AFM probes using chemical vapor deposition (CVD). (3) Direct CVD growth of nanotubes on AFM probes. (4) “Picking up” vertically grown CVD nanotube with AFM probes. Then, we discuss the optimal conditions for AFM imaging with carbon nanotube tips. We found that the tip-sample interactions during tapping mode AFM imaging could be either attractive or repulsive.; We also discuss five applications of carbon nanotube tips to chemistry and biology. First, we present the application of functionalized SWNT carbon nanotube tips for chemical force microscopy through examples of force titrations and functional mapping of patterned self-assembled monolayer surfaces. Second, we investigate the role of hSWI/SNF enzymes in chromatin remodeling. hSWI/SNF was found to remodel mononucleosomes into compact dimers. It remodeled polynucleosomes by shuffling the regularly spaced nucleosomes into clusters on the DNA. Third, we investigate the structural implication of enhanceosome and CREB-binding protein (CBP) in gene regulation. When CBP binded to the enhanceosome, a dramatic reorganization and compaction of the complex from a linear array of transcription factors was observed. Fourth, we study the indentation of diapalmitoylphosphatidylcholine lipid bilayer with carbon nanotube tips of different diameters. The bilayer rupture force was found to scale linearly with the cross-sectional area of the flat nanotube tips. Fifth, we report a novel approach to construct SWNT structures on surfaces by using long nanotubes on nanotube tips as building blocks.; Finally, we describe preliminary results on three future applications of carbon nanotube tips: (1) Carbon nanotubes tips as nanostraws and nanoink-jet. (2) Carbon nanotube tips for molecular friction measurement. (3) Carbon nanotubes as electromechanical switches. |
