Multiplex measurement of seven tumor markers using an electrochemical protein chip.

An electrochemical immunosensor for performing multianalyte measurements of tumor markers is described. The sensor consisted of an array of immunosensing electrodes fabricated on a glass substrate. Each electrode contained a different immobilized antigen and was capable of measuring a specific tumor marker using electrochemical enzyme-based competitive immunoassay. Using this arrangement, multiple analytes could be measured simultaneously by performing the technical operations for a single assay. The biosensor was used to measure the concentrations of seven important tumor markers: AFP, ferritin, CEA, hCG-beta, CA 15-3, CA 125, and CA 19-9. The sensor had excellent precision and accuracy and was comparable in performance to single-analyte ELISAs (1.9-8.1% interassay CV; <2 ng/mL (or units/mL) detection limit for most analytes). Multianalyte assays provide significant advantages over single-analyte tests in terms of cost per test, labor, test throughput, and convenience. We anticipate that chip-based sensors, as described herein, will be suitable for the mass production of economical, miniaturized lab-on-a-chip devices that will have applications in a wide range of clinical, environmental, and biodefense applications.