title: A fluorescent nanoprobe for single bacterium tracking: functionalization of silver nanoparticles with tryptophan to probe the nanoparticle accumulation with single cell resolution.
abstract: The investigation of the interaction of silver nanoparticles and live bacteria cells is of particular importance for understanding and controlling their bactericidal properties. In this study, the process of internalization of silver nanoparticles in Escherichia coli cells was followed by means of synchrotron excitation deep ultraviolet (DUV) fluorescence imaging. Antimicrobial nanostructures that can absorb and emit light in the UV region were prepared by functionalization of silver nanoparticles with tryptophan amino acid and used as environmentally sensitive fluorescent probes. The nanostructures were characterized by morphological (TEM) and spectroscopic methods (UV-vis, FTIR, XPS, and photoluminescence). The TEM images and the analyses of the UV-vis spectra suggested that the addition of tryptophan led to the formation of hybrid nanostructures with pronounced eccentricity and larger sizes with respect to that of the initial silver nanoparticles. The DUV imaging showed that it was possible to distinguish the fluorescent signal pertaining to silver-tryptophan nanostructures from the autofluorescence of the bacteria. The spatial resolution of the fluorescence images was 154 nm which was sufficient to perform analyses of the accumulation of the nanostructures within a single bacterium. The DUV imaging results imply that the tryptophan-functionalized silver nanoparticles interact with cell membranes via insertion of the amino acid into the phospholipid bilayer and enter the cells.
authors: University of Belgrade, Vinča Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade, Serbia. bozanic@vinca.rs djokovic@vinca.rs.
authors: R
authors: R
authors: Dojčilović
authors: University of Belgrade, Faculty of Physics, P.O. Box 368, 11001 Belgrade, Serbia.
authors: J D
authors: JD
authors: Pajović
authors: University of Belgrade, Vinča Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade, Serbia. bozanic@vinca.rs djokovic@vinca.rs.
authors: D K
authors: DK
authors: Božanić
authors: University of Belgrade, Vinča Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade, Serbia. bozanic@vinca.rs djokovic@vinca.rs.
authors: V V
authors: VV
authors: Vodnik
authors: University of Belgrade, Department of Bioengineering and Biotechnology, Faculty of Technology and Metallurgy, Karnegijeva 4, 11120 Belgrade, Serbia.
authors: S
authors: S
authors: Dimitrijević-Branković
authors: University of Belgrade, Institute of Physics Belgrade, Pregrevica 118, 11080 Belgrade, Serbia.
authors: A R
authors: AR
authors: Milosavljević
authors: University Paris-Sud 11, UMR-S785, F-94800 Villejuif, France and Inser U785, F-94800 Villejuif, France.
authors: S
authors: S
authors: Kaščàkovà
authors: DISCO Beamline, Synchrotron SOLEIL, F-91192 Gif sur Yvette, France.
authors: M
authors: M
authors: Réfrégiers
authors: University of Belgrade, Vinča Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade, Serbia. bozanic@vinca.rs djokovic@vinca.rs.
authors: V
authors: V
authors: Djoković
mesh_terms: D004926:Escherichia coli / Q000166:cytology* / Q000378:metabolism*; D005456:Fluorescent Dyes / Q000737:chemistry*; D053768:Metal Nanoparticles; D061848:Optical Imaging; D012834:Silver / Q000737:chemistry* / Q000378:metabolism*; D059010:Single-Cell Analysis / Q000295:instrumentation / Q000379:methods*; D017356:Synchrotrons; D014364:Tryptophan / Q000737:chemistry*
chemical_list: D005456:Fluorescent Dyes; D012834:Silver; D014364:Tryptophan