Bacterial detection using carbohydrate-functionalised CdS quantum dots: a model study exploiting E. coli recognition of mannosides

• Published in: Tetrahedron letters 2009-02, Vol.50 (8), p.886-889
• Main Authors: Mukhopadhyay, Balaram, Martins, Maristela B., Karamanska, Rositsa, Russell, David A., Field, Robert A.
• Format: Article
• Language: English
• ISSN: 0040-4039; 1873-3581
• DOI: 10.1016/j.tetlet.2008.12.029

Mannose-coated CdS quantum dots (Man-QDs) were prepared in a facile aqueous, one-pot process that exploits the self-assembly of thiolated mannose in the presence of CdS under reducing conditions. The resulting ∼15 nm diameter nanoparticles produce an intense, broad luminescence emission centred at 550 nm. These Man-QDs induce luminescent aggregates of Escherichia coli which can be used to detect bacteria in cell suspensions containing as few as 10 4 E. coli per mL. The aggregation process is dependent on the E. coli cell surface FimH mannose-specific lectin. The recognition and subsequent detection of the E. coli using the Man-QD has been shown to be specific as aggregation does not occur either with an E. coli strain defective in the FimH lectin or with galactose-coated QDs.