A review of microdialysis coupled to microchip electrophoresis for monitoring biological events

• On-line systems allow for near real-time monitoring of biological events.
• Systems can be customized with specific probes, separation, and detection methods.
• Several interface designs are presented for coupling MD to ME.
• Factors that affect temporal resolution in MD–ME are discussed.
• Applications of MD–ME for monitoring biological events both in vivo and in vitro.

Microdialysis is a powerful sampling technique that enables monitoring of dynamic processes in vitro and in vivo. The combination of microdialysis with chromatographic or electrophoretic methods with selective detection yields a “separation-based sensor” capable of monitoring multiple analytes in near real time. For monitoring biological events, analysis of microdialysis samples often requires techniques that are fast (<1 min), have low volume requirements (nL–pL), and, ideally, can be employed on-line. Microchip electrophoresis fulfills these requirements and also permits the possibility of integrating sample preparation and manipulation with detection strategies directly on-chip. Microdialysis coupled to microchip electrophoresis has been employed for monitoring biological events in vivo and in vitro. This review discusses technical considerations for coupling microdialysis sampling and microchip electrophoresis, including various interface designs, and current applications in the field.