Nanotechnology

TARGETING CANCER CELLS USING NANOTECHNOLOGY
INTRODUCTION:
Detection of dormant metastatic tumor cells is a critical but elusive goal in cancer treatment. To find these cells researchers are developing noninvasive optical imaging techniques that are less costly and more accessible than magnetic resonance imaging-based techniques and are free of the side effects associated with radioactive imaging agents.
The key to the new approach is a soft form of nanotechnology called polymersomes--microscopic, flexible "bubbles" made from polymers (long-chained molecules made from repeated smaller units). A polymersome’s unique structure and material properties allow it to carry a wide range of compounds in its water resistant membrane.
In this recent experiment, embedded fluorescent materials called porphyrins into the membrane of a polymersome. After injecting these emissive polymersomes directly into a tumor one centimeter beneath the surface of the skin of a mouse, he exposed the mouse to near-infrared light. The porphyrins emitted near-infrared signals detectable at the skin surface. These nanoscale assemblies [polymersomes] can generate the intense, highly localized near-infrared signals needed to penetrate dense tumor tissue in a live animal, In contrast to hard matter-based optical imaging agents, robust, near-infrared emissive polymersomes are ideally suited to impact a wide-range of medical applications.”
Deep Penetration with Near-Infrared Light
Compounds activated by near-infrared wavelengths were chosen because near-infrared light beams are not absorbed by water, hemoglobin and other compounds that make up living tissue. Consequently, they can penetrate deeply into tissue. Other dyes used for optical imaging emit in the ultraviolet or visible portion of the optical spectrum and penetrate only about a millimeter.
The large signal output of nanoscale near-infrared-emissive polymersomes will enable imaging of tissue as deep as 10 to 12 cm through breast tissue...