Title

Electrochemical Detection of Cancer Biomarkers

Date of Completion

January 2011

Keywords

Chemistry, Inorganic

Degree

Ph.D.

Abstract

The detection of proteins with clinical and diagnostic value has become an important method for detecting and following the progression of cancers. Electrochemical detection of these biomarkers offers an inexpensive and highly sensitive detection scheme for cancer biomarkers with the potential for point-of-care diagnostics. ^ Multi-enzyme carriers linked with an antibody can accomplish amplification of electrochemical protein detection, as a secondary antibody in sandwich immunoassay. A multi-enzyme-antibody-carbon nanotube prepared using functionalized multiwalled carbon nanotubes, anti-prostate specific antigen antibodies (anti-PSA), and horseradish peroxidase enzyme labels (HRP) was fully characterized. Analysis of the bioconjugate by electrochemistry, microscopy, and enzyme-catalyzed polymerization determined that the bioconjugate had ∼82 HRPs and 30±15 anti-PSA per 100 nm length of carbon nanotube and allowed for amplification over single enzyme secondary antibodies. Gold nanoparticles were printed into an eight-electrode electrochemical array utilizing inkjet printing. The gold nanoparticle platform was used to build a sandwich immunoassay for the protein biomarker interleukin-6 (IL-6). The fabricated arrays allowed for the electrochemical detection of IL-6 with a detection limit of 20 pg mL-1 in undiluted calf serum and a linear range from 20–400 pg mL-1 . These inkjet-printed gold arrays hold promise for use in multiplexed arrays and point-of-care diagnostics. ^