In Flow Metal Enhanced Fluorescence for Biolabelling and Biodetection

VEGLIA, A. V.; GONTERO, DANIELA; BRACAMONTE, A. G.

Photochemical and Photobiological Sciences

ROYAL SOC CHEMISTRY

Lugar: CAMBRIDGE; Año: 2020 p. 1 - 21

1474-905X

Escherichia coli bacteria were determined by in flow cytometry with laser excitation and fluorescencedetection applying ultraluminescent core?shell nanoparticles based on Metal Enhanced Fluorescence(MEF). Core?shell nanoparticles consisted of a 40 nm core modified with a silica spacer grafted withRhodamine B (RhB). The electromagnetic field in the near field of the core surface enhanced the fluorescenceof RhB by plasmonic and fluorophore coupling. The hydrophilic silica spacer allowed the noncovalentinteraction with the polar E. coli surface and thus ultraluminescent bacteria biolabelling wasdeveloped. Clearly, well defined and bright bacteria imaging was recorded by Laser FluorescenceMicroscopy based on the non-covalent deposition of the ultraluminescent nano-emitters. Using thesenano-labellers, it was possible to detect labelled E. coli by in flow cytometry. Higher values of Side-scatteredlight (SSC) and Forward-scattered light (FSC), and number of fluorescent event detections, wereobserved for labelled bacteria compared to those non-labelled. The sensitivity of the methodology wasevaluated by varying bacteria concentration and acceptable analytical figures of merit were determined.Applying this methodology we could quantify E. coli from a synthetic real sample of fortified water.Similar results were obtained by bacteria counting with Laser Fluorescence Microscopy and with a cellbacteriacounter.