There is a need for the development of very sensitive micro-analytical techniques for measuring proteins in biological fluids and single cells. One approach to such analysis is capillary electrophoresis (CE), which is a powerful analytical tool utilizing only nanoliters of materials. However, conventional detection systems are inadequate for the analysis of very small biological samples and single cells where many analytes are present in pico- and femto-gram quantities. The use of laser-induced fluorescence (LIF) has been demonstrated to be capable of overcoming many of the shortcomings of more conventional detection systems. At DBEPS, we have designed and developed a laboratory-built LIF detector capable of measuring fluorochrome-labeled analytes at approximately 400 femtograms. Although further refinement is required to ensure uniform labeling of multiple analytes pre-analysis, research into more advanced photon detectors is underway. Presently, a complete laboratory-built CE-LIF system has been constructed and is capable of routinely measuring analytes at the 1 pg/ml level. Further development will increase this sensitivity to the 1 femtogram/ml level or beyond. Once this is achieved, the instrument will be capable of reliable measurements of single cell secretions and/or cytosol in clinical and research samples. Coupling CE with an immunoaffinity pre-analysis step will further refine the capabilities of this instrument enabling it to analysis samples in the 10-100 pg range.
