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Facile synthesis and photophysical characterization of luminescent CdTe quantum dots for Forster resonance energy transfer based immunosensing of staphylococcal enterotoxin B
Author(s) -
Vinayaka Aaydha C.,
Thakur Munna S.
Publication year - 2012
Publication title -
luminescence
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.428
H-Index - 45
eISSN - 1522-7243
pISSN - 1522-7235
DOI - 10.1002/bio.2440
Subject(s) - quantum dot , förster resonance energy transfer , bioconjugation , quenching (fluorescence) , photoluminescence , luminescence , fluorescence , chemistry , biosensor , photochemistry , nanoparticle , materials science , analytical chemistry (journal) , nanotechnology , optoelectronics , organic chemistry , physics , quantum mechanics
Aqueous phase synthesis of CdTe quantum dots (QDs) with surface functionalization for bioconjugation remains the best approach for biosensing and bioimaging applications. We present a facile aqueous phase method to prepare CdTe QDs by adjusting precursor and ligand concentrations. CdTe QDs had photoluminescence quantum yield up to ≈33% with a narrow spectral distribution. The powder X‐ray diffraction profile elucidated characteristic broad peaks of zinc blende cubic CdTe nanoparticles with 2.5–3 nm average crystalline size having regular spherical morphology as revealed by transmission electron microscopy. Infra‐red spectroscopy confirmed disappearance of characteristic absorptions for –SH thiols inferring thiol coordinated CdTe nanoparticles. The effective molar concentration of 1 : 2.5 : 0.5 respectively for Cd 2+ /3‐mercaptopropionic acid/HTe – at pH 9 ± 0.2 resulted in CdTe quantum dots of 2.2–3.06 nm having band gap in the range 2.74–2.26 eV respectively. Later, QD 523 and QD 601 were used for monitoring staphylococcal enterotoxin B (SEB; a bacterial superantigen responsible for food poisoning) using Forster resonance energy transfer based two QD fluorescence. QD 523 and QD 601 were bioconjugated to anti‐SEB IgY antibody and SEB respectively according to carbodiimide protocol. The mutual affinity between SEB and anti‐SEB antibody was relied upon to obtain efficient energy transfer between respective QDs resulting in fluorescence quenching of QD 523 and fluorescence enhancement of QD 601 . Presence of SEB in the range 1–0.05 µg varied the rate of fluorescence quenching of QD 523 , thereby demonstrating efficient use of QDs in the Forster resonance energy transfer based immunosensing method by engineering the QD size. Copyright © 2012 John Wiley & Sons, Ltd.