Thiol-stabilized luminescent CdTe quantum dot as biological fluorescent probe for sensitive detection of methyl parathion by a fluoroimmunochromatographic technique

Quantum dots (QDs) are preferred as highresolution
biological fluorescent probes because of their
inherent optical properties compared with organic dyes. This
intrinsic property of QDs has been made use of for sensitive
detection of methylparathion (MP) at picogramme levels.
The specificity of the assay was attributed to highly specific
immunological reactions. Competitive binding between free
MP and CdTe QD bioconjugated MP (MP-BSA-CdTe) with
immobilized anti-MP IgY antibodies was monitored in a
flow-injection system. The fluorescence intensity of MPBSA-
CdTe bioconjugate eluted from the column was found
to be directly proportional to the free MP concentration.
Hence, it was possible to detect MP in a linear range of 0.1–
1 ng mL−1 with a regression coefficient R2=0.9905. In this
investigation, IgY proved advantageous over IgG class
immunoglobulins in terms of yield, stability, cost effectiveness,
and enhancement of assay sensitivity. The photoabsorption
spectrum of bioconjugated CdTe QD (λmax=
310 nm) confirmed nano-biomolecular interactions. The
results suggest the potential application of bioconjugation
and nano-biomolecular interactions of QDs for biological
labeling and target analyte detection with high sensitivity