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 cellular applications.

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.)