4th EucheMs chemistry congress

Poster Session 1
s903
chem. Listy 106, s587–s1425 (2012)
Poster session 1 - life sciences
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rAtionALLy deSiGned nir-fLuoreSCent
nAnoPArtiCLeS for BioAnALytiCAL
APPLiCAtionS
K. hoffMAnn 1 , t. BehnKe 1 , C. würth 1 ,
u. reSCh-GenGer 1
1 BAM Federal Institute for Materials Research and Testing, FB
1.10 Biophotonics, Berlin, Germany
Current trends in the life sciences are fluorescence-based
techniques and concepts for signal amplification and multiplexing
strategies to increase the overall detection sensitivity and to enable
the ratiometric and simultaneous detection of several analytes. [1]
This can be successfully achieved with fluorophore loaded
or labeled particles preferably emitting in the visible or nearinfrared
(NIR) spectral region. The detection within the diagnostic
window (650 to 950 nm) is advantageous to reduce scattering
effects and absorption from tissue and blood components and
signal contributions from autofluorescence. [2, 3] Moreover,
fluorophore incorporation into particles can reduce unspecific
interactions between the dye molecules and the surrounding
medium and can also minimize their potentially cytotoxic effects.
Furthermore, encapsulated NIR dyes often show an improved
photochemical and thermal stability as well as enhanced
fluorescence quantum yields in polar and protic solvents like
water. [4] For hydrophobic dyes with very low solubility in aqueous
media, encapsulation presents the only strategy for their use in
biologically relevant environments.
Here, we present the synthesis and characterization of bright
NIR-fluorescent polystyrene nanoparticles by a simple one-step
staining procedure which can be applied to all bioanalytically
relevant dye classes including xanthenes, cyanines, squaraines,
oxazines, and BODIPYs. [5] The resulting particles with various
surface functions and spectral properties have great potential for
cellular imaging and biomarker targeting. Applications as
ratiometric nanosensors for several analytes like oxygen, [6] and as
labels for lifetime multiplexing detection schemes will be
exemplary shown.
references:
1. U. Resch-Genger et al., Nature Methods 2008, 5, 763.
2. J. Yan et al., NanoToday 2007, 2, 44.
3. K.E. Adams et al., Journal of Biomedical Optics, 2007.
12(2): 024017-1.
4. V. Buschmann et al., Bioconj. Chem. 2003, 14, 195.
5. T. Behnke et al., Dyes and Pigments, 2012. 94(2): 247.
6. J. Napp et al., Analytical Chemistry, 2011. 83(23): 9039.
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forMAtion of Green ruSt SuLfAte And
CArBonAte in the PreSenCe of zn uSinG
tiMe-reSoLved in Situ SMALL– And
wide–AnGLe x-rAy SCAtterinG
i. AhMed 1 , S. ShAw 2 , L. BenninG 2
1 University of Lancaster, The Lancaster Environment Centre,
Lancaster, United Kingdom
2 Leeds University, School of Earth and Environment, Leeds,
United Kingdom
Email: i.ahmed@Lancaster.ac.uk
Green rusts (GR) nanoparticles are highly reactive iron
minerals that typically form under weakly acidic to alkaline
conditions in suboxic environments. GR have been shown to
significantly reduce the solubility and mobility of many toxic and
radioactive species in the environment, including Cr, U, Se, Ni
and Zn. GR is a lamellar double hydroxide solid with Fe2+ and
Fe3+ cations in the main hydroxide layer and anionic species (e.g.,
2– 2– SO , CO3 ) occupying the interlayer domain.
4
The formation mechanisms of green rust sulfate (GR-SO ) 4
and carbonate (GR-CO ) were determined using an in situ
3
approach combining time-resolved synchrotron-based Wide– and
Small–Angle X-ray Scattering with highly controlled chemical
synthesis and electrochemical monitoring of the reaction. Both
GR materials were coprecipitated under anaerobic conditions. The
reaction in both systems proceeded via a three stage reaction.
During the first stage schwertmannite [Fe O (OH) (SO ) ]
8 8 4.5 4 1.75
precipitated directly from solution at pH 2.8 - 4.5. With increasing
pH (> 5) Fe2+ ions adsorb to the surface of schwertmannite and
catalyse its transformation into goethite during the second stage
of the reaction. In the third stage, the hydrolysis of the adsorbed
Fe2+ ions on goethite initiates its transformation to GR-SO at pH 4
near 7. A fourth stage was identified at pH > 8.6 in the GR–CO3 system which involves an interlayer SO 4
4 th EucheMs chemistry congress
2– 2– /CO3 ion–exchange
process leading to the formation of the GR–CO phase. Evidences
3
on the incorporation of Zn2+ into the molecular structure of GR
are also presented.
references:
1. Ahmed, I. A. M.; Benning, L. G.; Kakonyi, G.;
Sumoondur, A. D.; Terrill, N. J.; Shaw, S. Formation of
Green Rust Sulfate: A combined in situ time-resolved
X-ray scattering and electrochemical Study. Langmuir 26
(9), 6593–6603 (2010).
Keywords: Wide Angle Scattering; Green Rust;
schwertmannite; Synchrotron; Coprecipitation;
AUGUst 26–30, 2012, PrAGUE, cZEcH rEPUbLIc