Nano-Imaging: Near-field scanning optical microscopy (NSOM)

Investigated in our laboratory is an emerging technique with its excellent resolving power less than 100 nanometer domains, and nondestructive nature compared to other scanning probe microscopic techniques. Non-destructive imaging of biomolecules in nanoscale domains is of considerable interest. At the single-molecule level resolution, it is possible to use the NSOM as a critical tool for visualization of cellular components labeled with fluorescent molecules. NSOM technology obtains more fundamental information about the cellular component’s orientation and locality without disturbing their original orientation and position, and level of interaction with surface. Several areas of science and medicine can benefit from this type of studies especially for molecular imaging, biomedical and biochip applications.

Currently we have investigated confocal microscopy and NSOM to study the localization of multidrug resistance (MDR) transport protein and their effect on chemotherapeutic drugs. Multidrug resistance (MDR) is the generic term used to indicate the variety of strategies that tumor cells are able to develop in order to evade cytotoxic effects of anticancer drugs. Previous studies have demonstrated that there are three major changes in cells that develop MDR: 1) decreased accumulation of cytotoxic drugs; 2) changes in activity or expression of certain cellular proteins, including the P-glycoprotein (Pgp, P for permeability), MDR-associated protein (MRP1), glutathione S-transferase p , protein kinase C and DNA topoisomerase II; and 3) changes in cellular physiology affecting the structure of the plasma membrane, the cytosolic pH, and the rates and extent of intracellular transport of membranes, as well as lysosomal structure and function. Current studies in our laboratory are focused to the investigation of these processes at the molecular and single-cell level.