Electric Signal Detection of a Microfilter-Based Biochip for Immunoassay Using Microbead, Nanogold Particle, and Silver Enhancement


Article Preview

This paper presents a microbiochip which can detect an antigen-antibody reaction through an electrical signal in real time with high sensitivity and low sample volume by using nanogold particle and silver enhancement. A filtration method using the microbead is adopted for sample immobilization. The chip is composed of an inexpensive and biocompatible Polydimethylsiloxane (PDMS) layer and Pyrex glass substrate. Platinum microelectrodes for electric signal detection were fabricated on the substrate and microchannel and pillar-type microfilters were formed in the PDMS layer. Successively introducing polystyrene microbeads precoated with protein A, anti-protein A (which was the first antibody) and the second antibody conjugated with nanogold particles into the microchannel, the resulting antigen-antibody complex was fixed on the bead surface. The injection of silver enhancer increased the size of nanogold particles tagged with the second antibody. As a result, microbeads were connected to each other and formed an electrical bridge between microelectrodes. Resistance measured through the electrodes showed a difference of two orders of magnitude between specific and nonspecific immunoreactions. The developed immunoassay chip reduced the time necessary for an antigen-antibody reaction to 10 min, thus shortening the overall analysis time from 3 hours to 50 min. The immunoassay chip reduces analysis time for clinical diagnoses, is simple, and has high sensitivity.



Key Engineering Materials (Volumes 326-328)

Edited by:

Soon-Bok Lee and Yun-Jae Kim




Y. J. Ko et al., "Electric Signal Detection of a Microfilter-Based Biochip for Immunoassay Using Microbead, Nanogold Particle, and Silver Enhancement", Key Engineering Materials, Vols. 326-328, pp. 839-842, 2006

Online since:

December 2006




[1] K. Sato, M. Tokeshi, T. Odake, H. Kimura, T. Ooi and M. Nakao: Anal. Chem. Vol. 72 (2000), p.1144.

[2] K. Sato, M. Yamanka, H. Takahashi, M. Tokeshi, H. Kimura and T. Kitamori: Electrophoresis Vol. 23 (2002), p.734.

[3] N.T. Kim and Z. Rosenzweig: Anal. Chem. Vol. 74 (2002), p.1624.

[4] J. -W. Choi, K.W. Oh, J.H. Thomas, W.R. Heineman, H.B. Halsall, J.H. Nevin, A.J. Helmicki, H.T. Henderson and C.H. Ahn: Lab Chip Vol. 2 (2002), p.27.

[5] R. -Q. Liang, C. -Y. Tan and K. -C. Ruan: Journal of Jmmunological Method Vol. 285 (2004), p.157.

[6] C. Luo, Q. Fu, H. Li, L. Xu, M. Sun, Q. Ouyang, Y. Chen and H. Ji: Lab Chip Vol. 5 (2005), p.726 �.

Fetching data from Crossref.
This may take some time to load.