Development of high-performance magnetic chemiluminescence enzyme immunoassay for alpha-fetoprotein (AFP) in human serum

Magnetic particle-based chemiluminescence enzyme immunoassay for free thyroxine in human serum

A magnetic particles-based chemiluminescence enzyme immunoassay with high sensitivity, specificity, rapidity, and reproducibility was developed for the determination of free thyroxine in human serum. A competitive assay has been proposed with horseradish peroxidase labeled thyroxine analog. The immunomagnetic particles coated with anti-fluorescein isothiocyanate antibody was used as dispersed solid phase and separation means for the immunoassay. Experimental conditions, such as temperature, the volume of magnetic particles and substrate, incubation time, dilution ratio and other relevant variables upon the immunoassay have been examined and optimized. The proposed method exhibited high performance which the linear range was 1.59-122 pmol L(-1) and the detection limit was 0.25 pmol L(-1). A coefficient of variance of less than 15% was obtained for both intra-assay and inter-assay precision. The present method has been successfully applied to the analysis of free thyroxine in human serum. The diagnostic accordance rate of the method for normal serum, hyperthyroidism and hypothyroidism are satisfactory. Good correlations were obtained between the results by the proposed method and the commercial radioimmunoassay kit. The present method exhibits good potential in the fabrication of FT4 diagnostic kits which could be used in the clinical analysis and facilitated the development of automated operation systems in the clinical practice.

Evaluation of alpha-fetoprotein (AFP) in human serum by chemiluminescence enzyme immunoassay with magnetic particles and coated tubes as solid phases

In this work, the monoclonal antibodies (McAbs) to alpha-fetoprotein (AFP) were immobilized on two different solid phases, i.e., magnetic particles (MP) and coated tubes (CT). Based on this, a MP based chemiluminescence enzyme immunoassay (MP-CLEIA) and a CT based CLEIA (CT-CLEIA) were proposed for the evaluation of AFP in human serum and their analytical merits were studied and compared. By detailed discussion of several performance variants, including the concentration of immobilized McAb, dilution ratio of horseradish peroxidase (HRP) labeled McAb (HRP-McAb), total assay time, substrate volume, chemiluminescent kinetics, and hook effect concentration, the advantages of MP-CLEIA became conspicuously apparent. Moreover, in the presence of MP, the catalytic activity of labeled enzyme was kept to high extent and the stability of immunoreagents was satisfied. Finally, 59 human serum samples were detected by the MP-CLEIA and a good correlation was obtained when comparing the results with that from a commercial electrochemiluminescence immunoassay kit.