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Materials 2013, 6(4), 1255-1269; doi:10.3390/ma6041255
Article

An Ultrasensitive Electrochemical Immunosensor for HIV p24 Based on Fe3O4@SiO2 Nanomagnetic Probes and Nanogold Colloid-Labeled Enzyme–Antibody Copolymer as Signal Tag

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Received: 24 December 2012; in revised form: 11 March 2013 / Accepted: 18 March 2013 / Published: 25 March 2013
(This article belongs to the Special Issue Advances in Nanoscale Biomaterials)
Download PDF [443 KB, uploaded 25 March 2013]
Abstract: An ultrasensitive portable electrochemical immunosensor for human immunodeficiency virus p24 (HIV p24) antigen detection has been developed, whereby the detection sensitivity was 1000 times higher than that of the ELISA method. Firstly, a novel HRP enzyme–antibody copolymer (EV-p24 Ab2) was synthesized through an EnVision regent (EV, a dextrin amine skeleton anchoring more than 100 molecules of HRP and 15 molecules of anti IgG), then incubated in the secondary antibody of p24. Secondly, the copolymer was immobilized on the gold nanocolloids (AuNPs) to fabricate a novel signal tag (AuNPs/EV-p24 Ab2). Subsequently, a sandwich-type immunoreaction would take place between the capture probe (silicon dioxide-coated magnetic Fe3O4 nanoparticles (MNPs) labeled with the primary p24 antibody (MNPs-p24 Ab1)), p24 (different concentrations) and the signal tag [AuNPs/EV-p24 Ab2)] to form the immunocomplex. Finally, the immunocomplex was absorbed on the surface of screen printed carbon electrode (SPCE) by a magnet and immersed in the o-hydroxyl phenol (HQ) and H2O2. The large amounts of HRP on the signal tag can catalyze the oxidation of HQ by H2O2, which can induce an amplified reductive current. Moreover, the capture probe could improve the accumulation ability of p24 and facilitate its separation from the substrate through the magnet. Under optimal conditions, the proposed immunoassay exhibited good sensitivity to p24 within a certain concentration range from 0.001 to 10.00 ng/mL, with a detection limit of 0.5 pg/mL (S/N = 3). The proposed method can be used for real-time and early detection of HIV-infected people.
Keywords: Fe3O4@SiO2 magnetic beads; nanogold-labeled EnVision antibody enzyme complex; HIV p24; signal amplification; electrochemical immunosensor Fe3O4@SiO2 magnetic beads; nanogold-labeled EnVision antibody enzyme complex; HIV p24; signal amplification; electrochemical immunosensor
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Gan, N.; Du, X.; Cao, Y.; Hu, F.; Li, T.; Jiang, Q. An Ultrasensitive Electrochemical Immunosensor for HIV p24 Based on Fe3O4@SiO2 Nanomagnetic Probes and Nanogold Colloid-Labeled Enzyme–Antibody Copolymer as Signal Tag. Materials 2013, 6, 1255-1269.

AMA Style

Gan N, Du X, Cao Y, Hu F, Li T, Jiang Q. An Ultrasensitive Electrochemical Immunosensor for HIV p24 Based on Fe3O4@SiO2 Nanomagnetic Probes and Nanogold Colloid-Labeled Enzyme–Antibody Copolymer as Signal Tag. Materials. 2013; 6(4):1255-1269.

Chicago/Turabian Style

Gan, Ning; Du, Xiaowen; Cao, Yuting; Hu, Futao; Li, Tianhua; Jiang, Qianli. 2013. "An Ultrasensitive Electrochemical Immunosensor for HIV p24 Based on Fe3O4@SiO2 Nanomagnetic Probes and Nanogold Colloid-Labeled Enzyme–Antibody Copolymer as Signal Tag." Materials 6, no. 4: 1255-1269.


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