Microbiochip for electrical detection of carcinoembryonic antigen using gold nanoparticles and silver enhancement

Abstract

The conventional immunoassay protocol for the detection of carcinoembryonic antigen (CEA) is expensive, laborious, and time-intensive. Additionally, it requires a very large detection device. In an effort to solve these problems, we have assessed the utility of a novel immunoassay technique based on microbeads and gold nanoparticles. In our microbiochip, we have adopted the filtration method to fix the microbeads, and used the immunogold silver staining (IGSS) method to amplify the electrical signal. The microbiochip was constructed of a Pyrex glass substrate and an inexpensive and biocompatible polydimethylsiloxane (PDMS) layer. The platinum (Pt) microelectrocle for electrical signal detection was fabricated on the substrate. A microchannel and pillar-type microfilter was formed in the PDMS layer. The colon cancer marker, CEA, was assayed via a sandwich immunoassay. As a result, we obtained significant resistance signal as the difference in CEA concentration. The total analysis time was less than one hour. A bead-based electrical detection system, such as the one described in this study, can be applied to systems for cancer diagnosis.