Capillary waveguide fluoroimmunosensor with improved repeatability and detection sensitivity |
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Authors: | Aristidis E Niotis Christos Mastichiadis Panagiota S Petrou Ion Christofidis Athanasia Siafaka-Kapadai Konstantinos Misiakos and Sotirios E Kakabakos |
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Institution: | (1) Immunoassay-Immunosensors Laboratory, Institute of Radioisotopes & Radiodiagnostic Products, N.C.S.R. “Demokritos”, Aghia Paraskevi, 15310 Athens, Greece;(2) Biochemistry Lab, Department of Chemistry, University of Athens, Panepistimiopolis, 15771 Athens, Greece;(3) Institute of Microelectronics, N.C.S.R. “Demokritos”, Aghia Paraskevi, 15310 Athens, Greece |
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Abstract: | An optical capillary waveguide fluoroimmunosensor based on glass capillaries internally coated with an ultrathin poly(dimethylsiloxane)
(PDMS) film is presented. The evaluation of the capillaries developed was done in comparison with aminosilanized 3-(aminopropyl)triethoxysilane,
APTES] glass and poly(methylpentene) (PMP) capillaries by immobilizing rabbit γ-globulins on the internal capillary wall.
Following reaction with (R)-phycoerythrin-labelled antibody, the capillary was scanned with a laser beam and the fluorescence waveguided through the
capillary wall was detected by a photomultiplier placed at one of its ends. The capillaries developed provided considerably
improved protein coating homogeneity (intracapillary coefficients of variation 2.9–6.6%) and repeatability (intercapillary
coefficients of variation 2.1–5.0%) compared with APTES-treated ones (7.9–13.4 and 8.5–15.2%, respectively). With use of these
capillaries in a sandwich-type immunosensor for the determination of rabbit γ-globulins, the assay detection limit was improved
eightfold (4.4 ng/mL) compared with that obtained using PMP capillaries (35.3 ng/mL), whereas the assay repeatability was
improved threefold (intra-assay coefficients of variation 5.9–13.1%) compared with APTES-treated capillaries (15.6–36%).
Optoelectronic set-up used to scan the capillaries (left) and representative fluorescence scannings of dual-band poly(methylpentene)
(PMP), PDMS-modified glass and APTES treated glass capillaries |
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Keywords: | Capillary fluoroimmunosensor Poly(dimethylsiloxane) emulsion Ultrathin poly(dimethylsiloxane) film Protein adsorption homogeneity (3-Aminopropyl)triethoxysilane Poly(methylpentene) capillary |
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