Residual nanoparticle label immunosensor for wash-free C-reactive protein detection in blood.
Current diagnostic immunotechnologies are universally based on the measurement of the bound label-antibody fraction in direct binding or sandwich-assay type approaches with various detection techniques (e.g. enzyme-linked immunosorbent assay or ELISA) on solid stationary phase surface. Here an alternative reciprocal approach is presented based on the detection of the non-bound fraction of nanoparticle-labelled antibodies using microparticles as solid support. The advantage of detecting the non-bound fraction of the labelled antibody instead of the bound fraction is the high dynamics and the suggested increased flexibility in the selection of the detection mode. No actual washing steps are required as the bound and non-bound fractions of the detection nanoparticle label are separated using physical separation rather than consecutive washing repeats. The quantitative proof-of-concept set-up was demonstrated through blood-based detection of C-reactive protein (CRP). A blood sample containing CRP was diluted 1/50 and measured in 15-min resulting in a linear response at a range from 1 to 30μg/ml. The lowest limit of detection was below 0.03μg/ml and the assay coefficient of variation ranged from 0.3 to 9%. The nanoparticle-based residual label detection outperformed the corresponding molecular label method providing wider applicability with nearly an order of magnitude higher signal-to-background ratio for novel assay configurations in clinical diagnostics practices.
Department of Cell Biology and Anatomy and Medicity Research Laboratories, Institute of Biomedicine, University of Turku, 20520 Turku, Finland.
Roope J
RJ
Huttunen
Department of Cell Biology and Anatomy and Medicity Research Laboratories, Institute of Biomedicine, University of Turku, 20520 Turku, Finland; Department of Neuroscience, Karolinska Institutet, von Eulers väg 3, 17177 Stockholm, Sweden.
Tuomas
T
Näreoja
Department of Cell Biology and Anatomy and Medicity Research Laboratories, Institute of Biomedicine, University of Turku, 20520 Turku, Finland.
Laura
L
Mariani
Department of Cell Biology and Anatomy and Medicity Research Laboratories, Institute of Biomedicine, University of Turku, 20520 Turku, Finland; Materials Chemistry and Chemical Analysis, Department of Chemistry, University of Turku, 20500 Turku, Finland. Electronic address: harri.harma@utu.fi.
Harri
H
Härmä
D000911:Antibodies, Monoclonal / Q000737:chemistry*; D015374:Biosensing Techniques / Q000379:methods*; D002097:C-Reactive Protein / Q000032:analysis*; D005063:Europium / Q000737:chemistry*; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D018796:Immunoconjugates / Q000737:chemistry; D057230:Limit of Detection; D008163:Luminescent Measurements / Q000379:methods; D053758:Nanoparticles / Q000737:chemistry*
D000911:Antibodies, Monoclonal; D018796:Immunoconjugates; D005063:Europium; D002097:C-Reactive Protein
Immunosensor; Nanoparticle; Time-resolved luminescence