To aid in the biochemical analysis of human skin biopsies, a semiautomatic chip-based CE system has been developed for measuring inflammatory biomarkers in microdissected areas of the biopsy. Following solubilization of the dissected tissue, the desired biomarkers were isolated by immunoaffinity capture using a panel of 12 antibodies, immobilized on a disposable glass fiber disk, within the extraction port of the chip. The captured analytes were labeled with a 635 nm light-emitting laser dye and electroeluted into the separation channel. Electrophoretic separation of all of the analytes was achieved in 2.2 min with quantification of each peak being performed by online LIF detection and integration of each peak area. Comparison of the results obtained from the chip-based system to those obtained using commercially available high-sensitivity immunoassays demonstrated that the chipbased assay provides a fast, accurate procedure for studying the concentrations of inflammatory biomarkers in complex biological materials. The degree of accuracy and precision achieved by the chip-based CE is comparable to conventional immunoassays and the system is capable of analyzing circa six samples per hour. With the ever-expanding array of antibodies that are commercially available, this chip-based system can be applied to a wide variety of different biomedical analyses.

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A chip-based immunocapillary electrophoresis system has been employed to measure the concentrations of brain-derived neurotrophic factor (BDNF) in human skin biopsies, taken during atopic inflammatory events. The device employs a replaceable immunoaffinity disk to which capture antibodies have been chemically immobilized. Homogenates obtained from microdissected human skin samples were injected into the system where the analyte of interest was captured in the immunoextraction port, thus allowing non-reactive materials to be removed prior to analysis. The captured analyte was labeled in situ with a red-emitting laser dye before being released from the capture antibody, separated by electrophoresis, and the resolved peaks detected by on-line laser-induced fluorescence. Comparison of this chip-based system to conventional immunoassay demonstrated good correlation when analyzing both standards and patient samples. The system was semi-automated resulting in a CE analysis within 1.5 min and a total of circa 5 min. Intra-and inter-assay CV's of 3.85 and 4.19 were achieved with circa 98.8% recovery of BDNF at a concentration of 100 pg/mL. The assay demonstrated clear differences between clinical stages of atopic dermatitis in human patients and could run 10-15 samples per hour. This system holds the potential for being modified to be a portable unit that could be used in clinics and other biomedical screening studies.

An electrokinetic immunoassay performed in a chip-based capillary electrophoresis system is described for the rapid measurement of naproxen in human plasma. The system employs a fluorescently labeled antibody to capture and detect the analyte of interest within a 5 min total assay time with an LOD of 0.025 microg/mL and a saturation level of 450 microg/mL. The system compared well with a conventional HPLC technique but was found to be much faster. Application of the electrokinetic assay to the study of patients with allergy to naproxen demonstrated increased concentrations of the drug extending past the predicted elimination half-life. The portability of the system and its ability to process up to 18 samples per hour makes it suitable for use in emergency room situations.