Fe₃O₄/Au magnetic nanoparticle amplification strategies for ultrasensitive electrochemical immunoassay of alfa-fetoprotein.
BACKGROUND
The purpose of this study was to devise a novel electrochemical immunosensor for ultrasensitive detection of alfa-fetoprotein based on Fe(3)O(4)/Au nanoparticles as a carrier using a multienzyme amplification strategy.


RESULTS
Greatly enhanced sensitivity was achieved using bioconjugates containing horseradish peroxidase (HRP) and a secondary antibody (Ab(2)) linked to Fe(3)O(4)/Au nanoparticles (Fe(3)O(4)/Au-HRP-Ab(2)) at a high HRP/Ab(2) ratio. After a sandwich immunoreaction, the Fe(3)O(4)/Au-HRP-Ab(2) captured on the electrode surface produced an amplified electrocatalytic response by reduction of enzymatically oxidized hydroquinone in the presence of hydrogen peroxide. The high content of HRP in the Fe(3)O(4)/Au-HRP-Ab(2) could greatly amplify the electrochemical signal. Under optimal conditions, the reduction current increased with increasing alfa-fetoprotein concentration in the sample, and exhibited a dynamic range of 0.005-10 ng/mL with a detection limit of 3 pg/mL.


CONCLUSIONS
The amplified immunoassay developed in this work shows good precision, acceptable stability, and reproducibility, and can be used for detection of alfa-fetoprotein in real samples, so provides a potential alternative tool for detection of protein in the laboratory. Furthermore, this immunosensor could be regenerated by simply using an external magnetic field.
The State Key Laboratory Base of Novel Functional Materials and Preparation Science, Faculty of Material Science and Chemical Engineering, Ningbo University, Ningbo, People’s Republic of China. ganning@nbu.edu.cn
Ning
N
Gan
Haijuan
H
Jin
Tianhua
T
Li
Lei
L
Zheng
D015374:Biosensing Techniques / Q000295:instrumentation*; D003217:Conductometry / Q000295:instrumentation; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005290:Ferric Compounds / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D006735:Horseradish Peroxidase / Q000737:chemistry / Q000276:immunology; D007118:Immunoassay / Q000295:instrumentation*; D058185:Magnetite Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology / Q000295:instrumentation*; D000509:alpha-Fetoproteins / Q000032:analysis* / Q000276:immunology
D005290:Ferric Compounds; D058185:Magnetite Nanoparticles; D000509:alpha-Fetoproteins; C000499:ferric oxide; D006046:Gold; D006735:Horseradish Peroxidase