Near-field scanning optical microscopy for bioanalysis at nanometer resolution.

The nondestructive imaging of biomolecules in nanometer domains in their original location and position as adsorbed or deposited on a surface is of garners considerable experimental interest. Near-field scanning optical microscopy (NSOM) is an emerging technique with its astonishing resolving power of <100-nm domains, and nondestructive nature compared with other scanning probe microscopic techniques is an emerging technique to achieve this goal. At the single-molecule level of resolution, it is possible to use the NSOM as a critical tool for visualization of proteins on surfaces to obtain more fundamental information about their orientation and locality without disturbing their original orientation and position, and level of interaction with the surface. Several areas of science and medicine can benefit from this type of study especially for biomedical and biochip applications. To illustrate possible applications, imaging of green fluorescent proteins and biomolecules associated with multidrug resistance proteins in tumor cells will be demonstrated using NSOM.