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Updated: Jun 21, 2026
A Method for Selecting Structure-switching Aptamers Applied to a Colorimetric Gold Nanoparticle Assay
Published on: February 28, 2015
A novel, label-free immunosensor for the detection of alpha-fetoprotein using functionalised gold nanoparticles
Wenbin Liang1, Weijing Yi, Shuhui Li
1Chongqing Key Laboratory of Analytical Chemistry, College of Chemistry and Chemical Engineering, Southwest University, Chongqing, PR China.
Background And Objectives:
Novel immunoassay methods based on electrochemical sensors have been developed, but most of these immunosensors are unsuitable for clinical detection because their preparation requires complicated chemical procedures and because their detection sensitivity is restricted. In order to develop a highly sensitive, label-free amperometric sensor for immunoassays, we synthesised novel, functionalized gold nanoparticles (SV-GNP) by covalently capping the surface of gold nanoparticles (GNP) with 1,1'-bis-(2-mercapto)-4,4'-bipyridinium dibromide, a kind of sulfhyrdryl viologen (SV).
Design And Methods:
We fabricated an immunosensor in a multi-step fashion, by first coating the SV-GNP onto a glassy carbon electrode surface; the resulting electrode core could then adsorb a suitable antibody in a second step to afford the desired immunosensor. alpha-fetoprotein (AFP) was used as a model analyte in this work.
Results:
The anti-AFP/SV-GNP-modified electrode was sensitive to AFP with a linear relationship between 1.25 and 200 ng/mL and a correlation coefficient of 0.9983; the detection limit at a signal to noise ratio of 3 was 0.23 ng/mL under optimal conditions. In addition, the proposed immunosensor exhibited good sensitivity, selectivity, stability and long-term maintenance of bioactivity.
Conclusion:
The described immunosensor preparation and immunoassay methods offer promise for label-free, simple, and cost-effective analysis of biological samples.
