Immunological assay for carbohydrate antigen 19-9 using an electrochemical immunosensor and antigen immobilization in titania sol-gel matrix.
We describe a novel electrochemical immunosensor for carbohydrate antigen 19-9 (CA19-9) based on the immobilization of CA19-9 with titania sol-gel on a graphite electrode (GE) by vapor deposition. The CA19-9 membrane was characterized using scanning electron microscopy and proved to be chemically clean, porous and homogeneous. The incubation of the immunosensor in a solution containing horseradish peroxidase (HRP)-labeled CA19-9 antibody led to the binding of HRP-labeled antibody with the immobilized antigen. The immobilized HRP catalyzed the oxidation of catechol by H(2)O(2) and this provided a competitive method for the measurement of serum CA19-9. The response current decreased with increasing CA19-9 concentration in the incubation solution. The effects of pH, amount of HRP-labeled antibody, incubation time and temperature were explored to provide optimum analytical performance. Under optimal conditions, the current decrease of the immunosensor was proportional to CA19-9 concentrations in the range of 3-20 U/ml with a detection limit of 2.68 U/ml at a current decrease of 10%. The detection of CA19-9 in two serum samples obtained from clinically diagnosed patients with pancreatic carcinoma showed acceptable accuracy. The proposed immunosensor provides a new promising tool for the clinical immunoassay of CA19-9.
Du
Dan
D
State Key Laboratory of Coordination Chemistry, Department of Chemistry, Institute of Analytical Science, Nanjing University, 210093 Nanjing, PR China.
Yan
Feng
F
Liu
Shengli
S
Ju
Huangxian
H
D015374:Biosensing Techniques / Q000379:methods*; D018395:CA-19-9 Antigen / Q000097:blood*; D004563:Electrochemistry; D005782:Gels; D007118:Immunoassay / Q000379:methods*; D008855:Microscopy, Electron, Scanning; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014025:Titanium
D018395:CA-19-9 Antigen; D005782:Gels; C009495:titanium dioxide; D014025:Titanium