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Gold nanoparticle-based fluorescence immunoassay for malaria antigen detection

Guirgis, Bassem S. S and Cunha, Claudia Sá e and Gomes, Inês and Cavadas, Miguel and Silva, Isabel and Doria, Gonçalo and Blatch, Gregory L and Baptista, Pedro V and Pereira, Eulália and Azzazy, Hassan M. E and Mota, Maria M and Prudêncio, Miguel and Franco, Ricardo (2012) Gold nanoparticle-based fluorescence immunoassay for malaria antigen detection. Analytical and Bioanalytical Chemistry, 402 (3). pp. 1019-1027. ISSN 1618-2642 (print) 1618-2650 (online)

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Abstract

The development of rapid detection assays for malaria diagnostics is an area of intensive research, as the traditional microscopic analysis of blood smears is cumbersome and requires skilled personnel. Here, we describe a simple and sensitive immunoassay that successfully detects malaria antigens in infected blood cultures. This homogeneous assay is based on the fluorescence quenching of cyanine 3B (Cy3B)-labeled recombinant Plasmodium falciparum heat shock protein 70 (PfHsp70) upon binding to gold nanoparticles (AuNPs) functionalized with an anti-Hsp70 monoclonal antibody. Upon competition with the free antigen, the Cy3B-labeled recombinant PfHsp70 is released to solution resulting in an increase of fluorescence intensity. Two types of AuNP-antibody conjugates were used as probes, one obtained by electrostatic adsorption of the antibody on AuNPs surface and the other by covalent bonding using protein cross-linking agents. In comparison with cross-linked antibodies, electrostatic adsorption of the antibodies to the AuNPs surfaces generated conjugates with increased activity and linearity of response, within a range of antigen concentration from 8.2 to 23.8 μg.mL−1. The estimated LOD for the assay is 2.4 μg.mL−1 and the LOQ is 7.3 μg.mL−1. The fluorescence immunoassay was successfully applied to the detection of antigen in malaria-infected human blood cultures at a 3% parasitemia level, and is assumed to detect parasite densities as low as 1,000 parasites.μL−1.

Item Type: Article
Uncontrolled Keywords: ResPubID25399, malaria diagnosis, gold nanoparticles, nanodiagnosis, heat shock proteins, fluorescence, detection, immunoassay, plasmodium
Subjects: FOR Classification > 0601 Biochemistry and Cell Biology
FOR Classification > 0605 Microbiology
Faculty/School/Research Centre/Department > College of Health and Biomedicine
Depositing User: Yimin Zeng
Date Deposited: 25 Feb 2014 22:38
Last Modified: 28 Aug 2014 23:11
URI: http://vuir.vu.edu.au/id/eprint/23519
DOI: 10.1007/s00216-011-5489-y
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Citations in Scopus: 12 - View on Scopus

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