Luminescent Gold Surfaces for Sensing and Imaging: Patterning of Transition Metal Probes

Luminescent transition metal complexes are introduced for the microcontact printing of optoelectronic devices. Novel ruthenium­(II), RubpySS, osmium­(II), OsbpySS, and cyclometalated iridium­(III), IrbpySS, bipyridyl complexes with long spacers between the surface-active groups and the metal were developed to reduce the distance-dependent, nonradiative quenching pathways by the gold surface. Indeed, surface-immobilized RubpySS and IrbpySS display strong red and green luminescence, respectively, on planar gold surfaces with luminescence lifetimes of 210 ns (RubpySS·Au) and 130 and 12 ns (83%, 17%) (IrbpySS·Au). The modified surfaces show enhancement of their luminescence lifetime in comparison with solutions of the respective metal complexes, supporting the strong luminescence signal observed and introducing them as ideal inorganic probes for imaging applications. Through the technique of microcontact printing, complexes were assembled in patterns defined by the stamp. Images of the red and green patterns rendered by the RubpySS·Au and IrbpySS·Au monolayers were revealed by luminescence microscopy studies. The potential of the luminescent surfaces to respond to biomolecular recognition events is demonstrated by addition of the dominant blood-pool protein, bovine serum albumin (BSA). Upon treatment of the surface with a BSA solution, the RubpySS·Au and IrbpySS·Au monolayers display a large luminescence signal increase, which can be quantified by time-resolved measurements. The interaction of BSA was also demonstrated by surface plasmon resonance (SPR) studies of the surfaces and in solution by circular dichroism spectroscopy (CD). Overall, the assembly of arrays of designed coordination complexes using a simple and direct μ-contact printing method is demonstrated in this study and represents a general route toward the manufacture of micropatterned optoelectronic devices designed for sensing applications

Untersuchung des Festigkeits- und Steifigkeitsverhaltens von Faserverbundwerkstoffen aus kaltaushaertenden Epoxidharzen fuer die Herstellung von Kleinflugzeugen. Teilbericht. Bd. 2 Ergebnisse der Harzgrundlagenuntersuchung

The present partial report of the research project documents the basic resin tests made. During a first test section, the softening temperatures of potentially suitable resin/hardener systems were determined by means of torsional oscillation tests. As a result of these tests, 4 systems were selected for more detailed investigations in the second test section. These additional tests comprised the determination of strength (tensile, compression, and shear) and determination of the associated elongations and elastic moduli in the tensile and compression tests. (orig./RHM)Der vorliegende Teilbericht des Forschungsvorhabens dokumentiert Harzgrundlagenuntersuchungen. In einem ersten Versuchsabschnitt wurden mit Hilfe von Torsionsschwingversuchen die Erweichungstemperaturen geeignet erscheinender Harz/Haertersysteme ermittelt. Als Ergebnis dieser Versuche wurden 4 Systeme fuer die weitergehende Untersuchung im zweiten Versuchsabschnitt ausgewaehlt. Diese weiteren Versuche umfassten die Ermittlung der Festigkeiten (Zug-, Druck-und Scherfestigkeit) sowie bei den Zug- und Druckversuchen die zugehoerigen Dehnungen und der Elastizitaetsmodule. (orig./RHM)Available from TIB Hannover: RO 5657(87-11)+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman

Synthesis of FITC alginate.

<p>(Ai) Reaction coupling scheme of FITC onto alginate under peptide coupling conditions. (Aii) Image of fluorescent alginate in normal light (left) and exposed to λ = 365 nm UV light (right). (B) Absorption and emission (red and blue lines respectively) spectra of the fluorescent alginate (FlAlg) product. The native alginate reactant has no absorption or emission profile, however, upon conjugation with FITC a highly absorption and emission peaks are observed.</p

Silica Nanoparticles for Micro-Particle Imaging Velocimetry: Fluorosurfactant Improves Nanoparticle Stability and Brightness of Immobilized Iridium(III) Complexes

To establish highly luminescent nanoparticles for monitoring fluid flows, we examined the preparation of silica nanoparticles based on immobilization of a cyclometalated iridium­(III) complex and an examination of the photophysical studies provided a good insight into the Ir­(III) microenvironment in order to reveal the most suitable silica nanoparticles for micro particle imaging velocimetry (μ-PIV) studies. Iridium complexes <i>covalently</i> incorporated at the surface of preformed silica nanoparticles, [Ir-4]@Si500-Z, using a fluorinated polymer during their preparation, demonstrated better stability than those without the polymer, [Ir-4]@Si500, as well as an increase in steady state photoluminescence intensity (and therefore particle brightness) and lifetimes which are increased by 7-fold compared with nanoparticles with the same metal complex attached covalently throughout their core, [Ir-4]⊂Si500. Screening of the nanoparticles in fluid flows using <i>epi</i>-luminescence microscopy also confirm that the brightest, and therefore most suitable particles for microparticle imaging velocimetry (μ-PIV) measurements are those with the Ir­(III) complex immobilized at the surface with fluorosurfactant, that is [Ir-4]@Si500-Z. μ-PIV studies demonstrate the suitability of these nanoparticles as nanotracers in microchannels

Effects of alginate on cellular iron transport.

<p>(A) Intracellular iron concentration decreases when RKO cells were incubated with iron-59 and alginate (0.3% w/v) compared to iron only control (B) Treatment of RKO cells with iron increases ferritin expression whilst co-incubation with alginate (0.3% w/v) significantly suppressed the iron mediated ferritin induction. All experiments were performed in triplicate with error bars representing +/- SEM and * denotes statistical significance at p < 0.05.</p

Cellular localisation of alginate with confocal microscopy.

<p>Cells were treated with iron alone (control) or iron and FITC alginate with or without cell-membrane permeabilisation. (A) Cells treated with iron alone as expected showed no FITC signal. (B) Cells treated with iron and FITC alginate showed negligible punctate FITC staining on the cell periphery (C) Cells permeabilised with Saponin and then cultured with iron and FITC alginate showed an abundance of intracellular FITC signal which was mostly cytoplasmic in localisation.</p

Physical characterisation of alginate iron composites.

<p>(Ai) Low magnification STEM images of alginate-iron composites revealed the alginate network ‘decorated’ in iron (denoted by arrows) with a single highly dense iron nucleation site (denoted with an asterisk). (Aii) A higher magnification image of the nucleation centre revealed nanoparticles of approximately 2–5 nm in diameter. (B) Fast Fourier transform analysis of HAADF-STEM images of two individual nanoparticles. (C) EDX mapping of iron-alginate composites with oxygen, iron and sodium localisation shown in the sample area. The copper from the copper TEM grid functions as a control.</p

Chemical analysis of iron alginate binding.

<p>(Ai) Isothermal titration microcalorimetry thermogram of 8 μl injectants of 5 mM Fe(III) into 0.04 mM alginate at 37°C. (Aii) Corresponding isotherm. (Bi) UV-Visible difference spectra of iron (III) titrated into alginate with a clear absorbance change at ca. 280 nm (Bii) absorbance change at 274nm vs final Fe concentration (M) with binding curve) (C) CD spectra of alginate-iron composites isolated via equilibrium dialysis. An induced CD signal is evident at ca. 280 nm. This correlates to the iron-hydroxide species bonded to the alginate as indicated from the UV-Visible spectra.</p

De Novo Design of Ln(III) Coiled Coils for Imaging Applications

A new peptide sequence (MB1) has been designed which, in the presence of a trivalent lanthanide ion, has been programmed to self-assemble to form a three stranded metallo-coiled coil, Ln­(III)­(MB1)₃. The binding site has been incorporated into the hydrophobic core using natural amino acids, restricting water access to the lanthanide. The resulting terbium coiled coil displays luminescent properties consistent with a lack of first coordination sphere water molecules. Despite this the gadolinium coiled coil, the first to be reported, displays promising magnetic resonance contrast capabilities

Iridium Nanoparticles for Multichannel Luminescence Lifetime Imaging, Mapping Localization in Live Cancer Cells

The development of long-lived luminescent nanoparticles for lifetime imaging is of wide interest as luminescence lifetime is environmentally sensitive detection independent of probe concentration. We report novel iridium-coated gold nanoparticles as probes for multiphoton lifetime imaging with characteristic long luminescent lifetimes based on iridium luminescence in the range of hundreds of nanoseconds and a short signal on the scale of picoseconds based on gold allowing multichannel detection. The tailor-made IrC₆ complex forms stable, water-soluble gold nanoparticles (AuNPs) of 13, 25, and 100 nm, bearing 1400, 3200, and 22 000 IrC₆ complexes per AuNP, respectively. The sensitivity of the iridium signal on the environment of the cell is evidenced with an observed variation of lifetimes. Clusters of iridium nanoparticles show lifetimes from 450 to 590 ns while lifetimes of 660 and 740 ns are an average of different points in the cytoplasm and nucleus. Independent luminescence lifetime studies of the nanoparticles in different media and under aggregation conditions postulate that the unusual long lifetimes observed can be attributed to interaction with proteins rather than nanoparticle aggregation. Total internal reflection fluorescence microscopy (TIRF), confocal microscopy studies and 3D luminescence lifetime stacks confirm the presence of bright, nonaggregated nanoparticles inside the cell. Inductively coupled plasma mass spectrometry (ICPMS) analysis further supports the presence of the nanoparticles in cells. The iridium-coated nanoparticles provide new nanoprobes for lifetime detection with dual channel monitoring. The combination of the sensitivity of the iridium signal to the cell environment together with the nanoscaffold to guide delivery offer opportunities for iridium nanoparticles for targeting and tracking in in vivo models