Gold nanoparticle-based fluorescence immunoassay for malaria antigen detection

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...

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Bibliographic Details
Published in:Analytical and bioanalytical chemistry 2012-01, Vol.402 (3), p.1019-1027
Main Authors: Guirgis, Bassem S. S., Sá e Cunha, Cláudia, Gomes, Inês, Cavadas, Miguel, Silva, Isabel, Doria, Gonçalo, Blatch, Gregory L., Baptista, Pedro V., Pereira, Eulália, Azzazy, Hassan M. E., Mota, Maria M., Prudêncio, Miguel, Franco, Ricardo
Format: Article
Language:English
Subjects:
Adsorption
Analysis
Analytical Chemistry
Antibodies, Monoclonal - chemistry
Antibodies, Monoclonal - immunology
Antigens
Antigens, Protozoan - analysis
Antigens, Protozoan - immunology
Biochemistry
Blood
Carbocyanines - chemistry
Characterization and Evaluation of Materials
Chemistry
Chemistry and Materials Science
Culture
Fluorescence
Fluorescent Antibody Technique - methods
Fluorescent Dyes - chemistry
Food Science
Gold - chemistry
Heat shock proteins
Hostages
HSP70 Heat-Shock Proteins - analysis
HSP70 Heat-Shock Proteins - immunology
Humans
Immunoassay
Laboratory Medicine
Malaria
Malaria - blood
Malaria - diagnosis
Malaria - immunology
Monitoring/Environmental Analysis
Monoclonal antibodies
Nanoparticles - chemistry
Nanostructure
Original Paper
Plasmodium falciparum
Plasmodium falciparum - immunology
Plasmodium falciparum - isolation & purification
Protein binding
Protozoan Proteins - analysis
Protozoan Proteins - immunology
Recombinant Proteins - analysis
Recombinant Proteins - immunology
Sensitivity and Specificity
Surface chemistry
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Description
Summary: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 ( Pf Hsp70) upon binding to gold nanoparticles (AuNPs) functionalized with an anti-Hsp70 monoclonal antibody. Upon competition with the free antigen, the Cy3B-labeled recombinant Pf Hsp70 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 . Figure A simple and sensitive competitive immunoassay based on fluorescence-quenching by gold nanoparticles, successfully detected malaria antigens in blood cultures infected with 1,000 parasites.μL -1 .
ISSN:1618-2642
1618-2650
DOI:10.1007/s00216-011-5489-y