Flow-injection immunoassay using OPA derivatization

Non-competitive immunoassay for luteinizing hormone in human serum using capillary electrophoresis with chemiluminescence detection

A non-competitive immunoassay based on capillary electrophoresis (CE) with chemiluminescence (CL) detection has been developed for the determination of luteinizing hormone (LH) in human serum. The work involved the development of separation and CL conditions, allowing for routine analysis of serum samples. In this study, horseradish peroxidase (HRP)-labelled monoclonal anti-LH can catalyse the luminol-hydrogen peroxide reaction. The determined LH can react with excessive amount of HRP-labelled anti-LH. Within 14 min, free enzyme conjugate and immune complex could be separated in alkaline borate buffer by means of a high voltage (15 kV). To improve sensitivity, a series of measures were adopted, including the choice of para-iodophenol as a CL enhancer, unique design in detect window. Under the optimal conditions, the calibration curve for LH was established in the concentration range 1-200 mIU/mL and the detection limit was 0.08 mIU/mL. Compared with ELISA, this method decreased the detection limit by about 12 times, and it has been successfully employed in the determination of LH in human serum.

A sensitive and rapid immunoassay for quantification of CA125 in human sera by capillary electrophoresis with enhanced chemiluminescence detection

In this paper we have presented a sensitive and rapid immunoassay (IA) method by capillary electrophoresis with an enhanced chemiluminescence detection system (CE-CL) based on the catalytic effects of horseradish peroxidase (HRP) on the luminol-hydrogen peroxide reaction. The conditions for the CL reaction and electrophoresis were systematically investigated using HRP as a model sample. The linear range from 2.5 x 10(-11) to 1.0 x 10(-9) mol/L (R = 0.999), and the detection limit of 1.0 x 10(-12) mol/L (signal-to-noise ratio = 3) for HRP were achieved using para-iodophenol as CL enhancer. The relative standard deviations of the migration time and peak area for 5.0 x 10(-10) mol/L HRP (n = 7) were 0.26 and 4.8%, respectively, using a CE system with a home-built CL detector. Under the optimal condition, the HRP-labeled CA125 antibody (Ab) and the Ab-antigen complex were well separated within 4 min by CE using a high-pH buffer (pH 10.20). The assay was successfully used for quantification of CA125 in human sera from health controls and patients associated with ovarian cancer, and the recoveries of the standard addition experiments were 93-109%. Our primary results demonstrated that IA based on CE-CL detection is a powerful tool for clinical diagnosis combined with these commercial IA kits.

Flow immunochemical bio-recognition detection for the determination of interleukin-10 in cell samples

On- and off-line heterogeneous non-competitive flow immunoassays for the determination of Interleukin-10 are described. The sample containing IL-10 is mixed, either on-line in a reaction coil or off-line in a test tube, with fluorescent labelled anti-IL-10 antibodies to form an antibody-antigen complex. The labelled unbound antibodies are trapped on an immobilized IL-10 column whereas the IL-10-antibody complexes are eluted and detected downstream by a fluorescence detector. The optimization of the systems was performed with respect to choice of affinity support, flow rate, carrier buffer additives, pH and antibody-antigen association. Both bio recognition assays were tested with a spiked cell medium and the IL-10 detection limits in this matrix was found to be 8 fmol using the off-line incubation mode and 40 fmol using the on-line incubation mode. The sample through-put was 26 and 40 samples per hour in the on-line and off-line incubation modes, respectively. IL-10 identification in the sample fractions was achieved using MALDI-TOF MS.