Interaction of amino acid-functionalized silver nanoparticles and Candida albicans polymorphs: A deep-UV fluorescence imaging study

Colloids Surf B Biointerfaces. 2017 Jul 1;155:341-348. doi: 10.1016/j.colsurfb.2017.04.044. Epub 2017 Apr 23.

Abstract

The interaction of the tryptophan functionalized Ag nanoparticles and live Candida albicans cells was studied by synchrotron excitation deep-ultraviolet (DUV) fluorescence imaging at the DISCO beamline of Synchrotron SOLEIL. DUV imaging showed that incubation of the fungus with functionalized nanoparticles results in significant increase in the fluorescence signal. The analysis of the images revealed that the interaction of the nanoparticles with (pseudo)hyphae polymorphs of the diploid fungus was less pronounced than in the case of yeast cells or budding spores. The changes in the intensity of the fluorescence signals of the cells after incubation were followed in [327-353nm] and [370-410nm] spectral ranges that correspond to the fluorescence of tryptophan in non-polar and polar environment, respectively. As a consequence of the environmental sensitivity of the silver-tryptophan fluorescent nanoprobe, we were able to determine the possible accumulation sites of the nanoparticles. The analysis of the intensity decay kinetics showed that the photobleaching effects were more pronounced in the case of the functionalized nanoparticle treated cells. The results of time-integrated emission in the mentioned spectral ranges suggested that the nanoparticles penetrate the cells, but that the majority of the nanoparticles attach to the cells' surfaces.

Keywords: C. albicans; Fluorescence imaging; Functionalization; Silver nanoparticles; Tryptophan.

MeSH terms

  • Antifungal Agents / chemistry
  • Antifungal Agents / metabolism
  • Antifungal Agents / pharmacology*
  • Candida albicans / drug effects*
  • Candida albicans / growth & development
  • Candida albicans / metabolism
  • Candida albicans / ultrastructure
  • Hyphae / drug effects*
  • Hyphae / growth & development
  • Hyphae / metabolism
  • Hyphae / ultrastructure
  • Kinetics
  • Metal Nanoparticles / chemistry*
  • Optical Imaging / methods
  • Silver / chemistry
  • Silver / metabolism
  • Silver / pharmacology*
  • Spores, Fungal / drug effects*
  • Spores, Fungal / growth & development
  • Spores, Fungal / metabolism
  • Spores, Fungal / ultrastructure
  • Synchrotrons
  • Tryptophan / chemistry
  • Ultraviolet Rays

Substances

  • Antifungal Agents
  • Silver
  • Tryptophan