Optical properties of fluorescein-labeled organoclay

Photochem Photobiol. 2010 May-Jun;86(3):520-7. doi: 10.1111/j.1751-1097.2009.00701.x. Epub 2010 Feb 11.

Abstract

We report the preparation of aminopropyl-functionalized magnesium phyllosilicate (Mg-organoclay) conjugated to fluorescein isothiocyanate (FITC) functionality (FITC-organoclay) by one-pot sol-gel synthesis. The physical characteristics of the Mg- and FITC-organoclays were examined by scanning electron microscopy (SEM), X-ray diffraction (XRD), FT-IR and UV-Vis spectrophotometry. X-ray fluorescence and elemental analysis were conducted to confirm the composition of the Mg-organoclay. The FITC-organoclay particles were polydispersed with an average particle size of approximately 50 nm, as determined from SEM images. The XRD patterns of FITC-organoclay exhibited broad peaks and reduced basal d(001) indicating a less condensed and more disordered structure than was observed for Mg-organoclay. The conjugation between FITC- and Mg-organoclay was characterized by FT-IR spectroscopy. Fluorescence excitation and emission spectral data demonstrated the successful conjugation of FITC dye molecules to the Mg-organoclay. The time-resolved fluorescence measurements revealed that FITC had a lifetime of 4.58 ns, whereas the lifetime of FITC-organoclay required a double exponential fit (tau(1,2) = 0.72 and 2.68 ns). As a result, the lifetime of the FITC-organoclay was shorter than that of FITC in ethanol and indicated moderate photostability in the solution state. The cellular uptake of FITC-organoclay in human lung alveolar carcinoma epithelial cells (A549) was quantified and characterized.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line, Tumor
  • Fluorescein-5-isothiocyanate / chemistry*
  • Fluorescence*
  • Fluorescent Dyes / chemical synthesis*
  • Fluorescent Dyes / pharmacokinetics
  • Humans
  • Lung Neoplasms / pathology
  • Nanoparticles / chemistry
  • Silicates / chemistry*

Substances

  • Fluorescent Dyes
  • Silicates
  • Fluorescein-5-isothiocyanate