Photoluminescent gold nanoclusters as sensing probes for uropathogenic Escherichia coli

PLoS One. 2013;8(3):e58064. doi: 10.1371/journal.pone.0058064. Epub 2013 Mar 15.

Abstract

Glycan-bound nanoprobes have been demonstrated as suitable sensing probes for bacteria containing glycan binding sites. In this study, we demonstrated a facile approach for generating glycan-bound gold nanoclusters (AuNCs). The generated AuNCs were used as sensing probes for corresponding target bacteria. Mannose-capped AuNCs (AuNCs@Mann) were generated and used as the model sensors for target bacteria. A one-step synthesis approach was employed to generate AuNCs@Mann. In this approach, an aqueous solution of tetrachloroauric acid and mannoside that functionized with a thiol group (Mann-SH) was stirred at room temperature for 48 h. The mannoside functions as reducing and capping agent. The size of the generated AuNCs@Mann is 1.95±0.27 nm, whereas the AuNCs with red photoluminescence have a maximum emission wavelength of ~630 nm (λexcitation = 375 nm). The synthesis of the AuNCs@Mann was accelerated by microwave heating, which enabled the synthesis of the AuNCs@Mann to complete within 1 h. The generated AuNCs@Mann are capable of selectively binding to the urinary tract infection isolate Escherichia coli J96 containing the mannose binding protein FimH expressed on the type 1 pili. On the basis of the naked eye observation, the limit of detection of the sensing approach is as low as ~2×10(6) cells/mL.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adhesins, Escherichia coli / biosynthesis
  • Adhesins, Escherichia coli / chemistry*
  • Bacterial Typing Techniques / methods*
  • Fimbriae Proteins / biosynthesis
  • Fimbriae Proteins / chemistry*
  • Fimbriae, Bacterial / chemistry
  • Fimbriae, Bacterial / metabolism
  • Gold / chemistry*
  • Luminescent Measurements / methods*
  • Mannose / chemistry
  • Metal Nanoparticles / chemistry*
  • Sensitivity and Specificity
  • Uropathogenic Escherichia coli / classification*
  • Uropathogenic Escherichia coli / metabolism

Substances

  • Adhesins, Escherichia coli
  • fimH protein, E coli
  • Fimbriae Proteins
  • Gold
  • Mannose

Grants and funding

This work was supported by the National Science Council of Taiwan (NSC 100-2627-M-009-007). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.