Biotechnology Letters

, Volume 28, Issue 8, pp 559–565

Direct Electrochemical Immunoassay Based on Immobilization of Protein-Magnetic Nanoparticle Composites on to Magnetic Electrode Surfaces by Sterically Enhanced Magnetic Field Force


DOI: 10.1007/s10529-006-0017-4

Cite this article as:
Tang, D., Yuan, R. & Chai, Y. Biotechnol Lett (2006) 28: 559. doi:10.1007/s10529-006-0017-4


A direct electrochemical immunoassay system based on the immobilization of α-1-fetoprotein antibody (anti-AFP), as a model system, on the surface of core-shell Fe2O3/Au magnetic nanoparticles (MNP) has been demonstrated. To fabricate such an assay system, anti-AFP was initially covalently immobilized on to the surface of core-shell Fe2O3/Au MNP. Anti-AFP-modified MNP (bio-nanoparticles) were then attached to the surface of carbon paste electrode with the aid of a permanent magnet. The performance and factors influencing the performance of the resulting immunosensor were studied. α-1-Fetoprotein antigen was directly determined by the change in current or potential before and after the antigen–antibody reaction versus saturated calomel electrode. The electrochemical immunoassay system reached 95% of steady-state potential within 2 min and had a sensitivity of 25.8 mV. The linear range for AFP determination was from 1 to 80 ng AFP ml−1 with a detection limit of 0.5 ng AFP ml−1. Moreover, the direct electrochemical immunoassay system, based on a functional MNP, can be developed further for DNA sensor and enzyme biosensor.


carbon paste electrodeelectrochemical assayα-1-fetoproteinmagnetic nanoparticles

Copyright information

© Springer 2006

Authors and Affiliations

  1. 1.Key Laboratory of Analytical Chemistry (Chongqing), College of Chemistry and Chemical EngineeringSouthwest UniversityChongqingP.R. China