Surface plasmon resonance aided electrochemical immunosensor for CK-MB determination in undiluted serum samples

FERNANDO GARAY; GREGGORY KISIEL; AIPING FANG; ERN&3377 LINDNER

ANALYTICAL AND BIOANALYTICAL CHEMISTRY

SPRINGER HEIDELBERG

Lugar: New York; Año: 2010 vol. 397 p. 1873 - 1881

1618-2642

This article presents a simple chronoamperometric immunosensor for the quantitative assessment of creatine kinase MB (CK-MB) in 50 ƒÊL undiluted serum samples. The immunosensor consists of gold working and counter electrodes patterned onto a glass chip by thin-film photolithography and an external Ag|AgCl reference electrode. The detection limit (DL) of the chronoamperometric method is 13 ng/mL (DL = 2~RMSD/S, where RMSD is the residual mean standard deviation of the measured points around a calibration curve with a slope of S). In spiked serum samples, the response was linear up to 300 ng/mL of CK-MB. A surface plasmon resonance (SPR) system with simultaneous electrochemical detection (EC-SPR) aided the development of the sandwich immunoassay. Real-time monitoring of the SPR signal was used to optimize the capture antibody immobilization, CK-MB and detection antibody binding, as well as to minimize the nonspecific adsorption of serum proteins to the sensor surface. The detection antibody has been labeled with alkaline phosphatase (ALP) enzyme for sensitive electrochemical detection. ALP catalyzes the hydrolysis of ascorbic acid phosphate and generates ascorbic acid, which is measured chronoamperometrically. The electrochemical immunoassay for CK-MB was less sensitive to nonspecific adsorption related interferences, had a better detection limit, and required a lower volume of sample than the SPR method.