NANOTECHNOLOGY—TECHNOLOGY ON A MOLECULAR SCALE - Chemistry: Notable Research and Discoveries - page 58

made of lead (Pb) and selenium (Se), and they adjusted the packing to
turn the solid from a nonconductor—in which coulombic (electrical)
interactions are blocked—into a semiconductor—in which conduc-
tion electrons “hop” among energy levels. The paper entitled “Coulomb
Blockade and Hopping Conduction in PbSe Quantum Dots” appeared
in Physical Review Letters.
Nanomaterial research is one of the richest branches of nanotech-
nology. But scientists and government officials have been impressed
with the potential of all the approaches to small-scale science and tech-
nology. Achieving this potential will require a lot more research—and
money to fund this research. To help meet this need, the U.S. govern-
ment launched the National Nanotechnology Initiative in 2001, as de-
scribed in the sidebar on pages 56-57.
One of the most important applications of nanotechnology is medicine.
Biology involves many small-scale objects such as the fundamental unit of
life—the cell—most of which are about 0.001-0.004 inches (0.0025-0.01
cm) in diameter, and proteins, the large molecules that perform a variety
of important functions in the body. Many of the diseases that afflict people
arise because of problems with certain cells or proteins.
nAnoTECHnologyInMEdICInE—
CAnCErdETECTIonAndTrEATMEnT
Although nanotechnology has a large number of applications in medi-
cine, this section will focus on cancer—the result of a cell or small group
of cells that grows out of control.
Growth is essential during development, as a baby matures into an
adult, and is also required in the maintenance and repair of an adult's tis-
sues. Cells make new tissue by growing and dividing—a cell divides into
two “daughter” cells, which generally have the same properties as the
original cell. Division continues until the needed tissue is complete.
Cellular division is a highly regulated process, subject to checks and
balances to ensure that growth occurs at a timely pace and in the cor-
rect amount. Too much tissue is just as bad as too little, and an out-of-
control cell could quickly divide and consume all of the body's nutrients
and available space. To prevent this, certain proteins monitor and regu-
late division. If something goes wrong and a cell begins to evade these