Colorimetric Enzyme Immunosensor for Carcinoembryonic Antigen Detection Based on Biomagnetic Beads

摘要

An ultrasensitive immunosensor has been developed based on using multiple signal antibodies immobilized on magnetic beads as labels for the detection of carcinoembryonic antigen. These biomagnetic beads were fabricated by sequentially conjugating HRP-labeled secondary antibody onto the protein G coated magnetic beads surface using glutaraldehyde as the linkage. After a sandwich antibody-antigen binding process, the captured biomagnetic beads tracer greatly catalyzed the TMB and H_2O_2 reaction to produce color responses. The signal was measured the absorbance at the wavelength of 450 nm. Under the optimum conditions, this immunosensor response was linear toward carcinoembryonic antigen in the concentration range from 0.01-50 ng/mL with a detection limit of 0.1 pg/mL. The precision, accuracy and specificity of the proposed immunosensor method were acceptable. Moreover, this assay was successfully applied for detection of carcinoembryonic antigen in serum samples. Analytical results of all samples from the developing immunosensor were in satisfactory agreement with those given by ELISA assay, indicating that a proposed method achieved for clinical diagnosis.