Advances in micro total analysis
Andreas Manz and his colleagues
at the Institute for Analytical Sciences in Dortmund, Germany, have reviewed recently
developed micro total analysis systems technologies, analytical standard operations
and applications of micro total analysis systems, focusing on fluidic systems and
The authors note that many optical
methods are used for detection in micro total analysis systems. Fluorescence microscopy,
for example, is used to detect labeled drugs and proteins and to characterize flow
velocity. They describe various techniques and technologies, including microchips
for total internal reflection microscopy, Fourier transform infrared spectroscopy,
surface-enhanced resonance Raman scattering and nuclear magnetic resonance spectroscopy.
They report biomaterials for microfluidic
systems and several three-dimentional devices and systems, including room-temperature
bonding techniques that do not require cleanrooms or high-temperature furnaces.
They also note that homogeneous surface modification techniques have been developed
for obtaining hydrophilic channel walls with improved control over electro-osmotic
flow and for better separation of biological samples.
Chip designs have been created for
manipulation of trapped particles and living cells and for separation of proteins.
The reviewers describe several electro-osmotic pumps for fluid transport, along
with strategies to form reversible plugs that open and close microchannels to alter
liquid flow. They also discuss sample preparation methods via electric field application
and techniques for fluid and particle handling and separation, including electrophoresis,
chromatography as well as size-dependent, chiral and electrokinetic separation.
These and other techniques have been
used in a variety of cellular applications, such as cytometry and cell assays. The
authors also report their use in clinical diagnosis and DNA analysis and in environmental
applications such as determination of copper or hydrogen peroxide in water samples.
Others include the quantitative analysis of organic vapors and the spatial and temporal
resolution of gas flow profiles. (Analytical Chemistry, ASAP, April 28, 2006.)
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