Microchip electrophoresis bioanalytical applications

Microchip electrophoresis (MCE) is a novel analytical technique resulting from
miniaturization of capillary electrophoresis (CE) to a planar microfabricated separation
device. The consequences of the transfer of CE to MCE in terms of benefits and
drawbacks have been identified and commented. The strategies developed to overcome
the unfavourable features of the chip with respect to the capillary are briefly described.
A method for simultaneous separation of catecholamines and their cationic metabolites
has been developed on the microchip. The addition of three modifiers was required to
resolve all analytes. The sensitivity of on-chip amperometric detection has been
improved by employing an enzyme-catalyzed reaction on the amperometric electrode,
as well as by using a carbon nanotube-modified electrode. The developed analytical
methodology has been successfully applied for a direct on-chip determination of
catecholamines and their metabolites in a mouse brain homogenate. The feasibility of
performing affinity measurements as well as isoelectric focusing on the microchip has
been demonstrated and available applications of these two electrophoretic modes on a
chip have been reviewed. A commercial Shimadzu microchip station has for the first
time been applied for high-throughput microchip isoelectric focusing of therapeutic
proteins and obtained results have been compared to conventional capillary isoelectric
focusing.