Simple quantum dot bioprobe/label for sensitive detection of Staphylococcus aureus TNase

Staphylococcus aureus is a major human pathogen that elicits wide range of exo-toxic proteins that are responsible for diverse disease symptoms in humans. In the present study, sensitive and selective monoclonal antibody (mAb) based quantum dot fluorescent sensing platforms were developed for rapid detection of S. aureus, based on thermostable nuclease (TNase). It was observed, that after conjugation to CdTe QD-streptavidin, the anti-TNase antibody still possesses its bio-recognition specificity and bioactivity. Using this modified QD probe, simple to use immune assays such as nitrocellulose paper based dot-assay and fluorescence resonance energy transfer (FRET) assay were developed. Limit of detection (LOD) for the developed methods were stayed as 3 ng/mL for dot assay and 0.5 ng/mL for FRET assay. Developed methods were successfully validated on naturally contaminated samples and they showed a good linearity for calibrated detection of S. aureus in the tested samples. The results articulate the use of QD-antibody conjugate as bio-probe for the development of rapid and easy to use onsite detection platforms for infectious agents. QDs and its modifications were characterized by spectroscopy and microscopy techniques. (C) 2015 Elsevier B.V. All rights reserved.