Gravitational field-flow fractionation integrated with chemiluminescence detection for a self-standing point-of-care compact device in bioanalysis

A "Point-Of-Care-Testing" (POCT) system relies on portable and simply operated self-standing analytical devices. To fulfill diagnostic requirements, the POCT system should provide highly sensitive simultaneous detection of several biomarkers of the pathology of interest (multiplexing) in a short assay time. One of the main unsolved issues in POCT device development is the integration of pre-analytical sample preparation procedures in the miniaturized device. In this work, an integrated POCT system based on gravitational field-flow fractionation (GrFFF) and chemiluminescence (CL) detection is presented for the on-line sample pre-analytical treatment and/or clean-up and analysis of biological fluids. As a proof of principle for the new GrFFF-CL POCT system, the automatic on-line analysis of plasma alkaline phosphatase activity, a biomarker of obstructive liver diseases and bone disorders, starting from whole blood samples was developed. The GrFFF-CL POCT system was able to give quantitative results on blood samples from control and patients with low sample volume (0.5 mu L) and reagent consumption, short analysis time (10 minutes), high reproducibility and with a linear range of 50-1400 IU L-1. The system can be easily applied to on-line prepare plasma from whole blood for other clinical biomarkers and for other assay formats, based on immunoassay or DNA hybridization.