Filtern
Erscheinungsjahr
- 2011 (6) (entfernen)
Dokumenttyp
Schlagworte
- Fluorescence (5)
- Nanoparticles (4)
- NIR (3)
- Cancer (2)
- Microparticles (2)
- Near-infrared (2)
- Aggregation (1)
- Cell imaging (1)
- Cyanine dye (1)
- Dye-doped polymers (1)
Dye-biomolecule conjugates and NIR-fluorescent particles for targeting of disease-related biomarkers
(2011)
Indispensable for fluorescence imaging are highly specific and sensitive molecular probes that absorb and emit in the near infrared (NIR) spectral region and respond to or target molecular species or processes. Here, we present approaches to targeted fluorescent probes for in vivo imaging in the intensity and lifetime domain exploiting NIR dyes. Screening schemes for the fast identification of suitable fluorophores are derived and design criteria for highly emissive optical probes. In addition, as a signal amplification strategy that enables also the use of hydrophobic NIR fluorophores as fluorescent reporters, first steps towards versatile strategies for the preparation of NIR-fluorescent polymeric particles are presented that can be utilized also for the design of targeted and analyte-responsive probes.
Polystyrene nanoparticles (PS-NPs) were doped with an oxygen-sensitive near-infrared (NIR)-emissive palladium meso-tetraphenylporphyrin and an inert reference dye which are both excitable at 635 nm. The nanosensors were characterized with special emphasis on fundamental parameters such as absolute photoluminescence quantum yield and fluorescence lifetime. The PS-NPs were employed for ratiometric dual-wavelength and lifetime-based photoluminescent oxygen sensing. They were efficiently taken up by cultured murine alveolar macrophages, yielding a characteristic and reversible change in ratiometric response with decreasing oxygen concentration. This correlated with the cellular hypoxic status verified by analysis of hypoxia inducible factor-1α (HIF-1α) accumulation. In addition, the surface of PS-NPs was functionalized with polyethylene glycol (PEG) and the monoclonal antibody herceptin, and their binding to HER2/neu-overexpressing tumor cells was confirmed in vitro. First experiments with tumor-bearing mouse revealed a distinctive ratiometric response within the tumor upon hypoxic condition induced by animal sacrifice. These results demonstrate the potential of these referenced NIR nanosensors for in vitro and in vivo imaging that present a new generation of optical probes for oncology.
Encapsulation of hydrophobic dyes in polystyrene micro- and nanoparticles via swelling procedures
(2011)
Aiming at the derivation of a generalized
procedure for the straightforward preparation of particles
fluorescing in the visible and near-infrared (NIR) spectral
region, different swelling procedures for the loading of the
hydrophobic polarity-probe Nile Red into nano- and
micrometer sized polystyrene particles were studied and
compared with respect to the optical properties of the
resulting particles. The effect of the amount of incorporated
dye on the spectroscopic properties of the particles was
investigated for differently sized beads with different
surface chemistries, i.e., non-functionalized, aminomodified
and PEG-grafted surfaces. Moreover, photostability
and leaking studies were performed. The main criterion
for the optimization of the dye loading procedures was a
high and thermally and photochemically stable fluorescence
output of the particles for the future application of these
systems as fluorescent labels.
Unter dem Motto „Innovation und Qualitätssicherung in der (Bio)Analytik“ werden in der Arbeitsgruppe Fluoreszenzspektroskopie der BAM, Bundesanstalt für Materialforschung und -prüfung, funktionelle Chromophor-Systeme, einfache Signalverstärkungs- und Multiplexingstrategien sowie innovative Validierungs- und rückführbare Standardisierungskonzepte für verschiedene fluorometrische Messgrößen und Methoden entwickelt. Im Mittelpunkt stehen dabei molekulare Fluorophore, Nanokristalle mit größenabhängigen optischen Eigenschaften (sogenannte Quantenpunkte, QDs) und fluoreszierende Partikel variabler Größe sowie Sonden und Sensormoleküle für neutrale und ionische Analyte und für die Charakterisierung von funktionellen Gruppen. Dabei erfolgen auch methodische Entwicklungen für die Fluoreszenzspektroskopie, die Fluoreszenzmikroskopie, die Milcrofluorometrie, die Sensorik und die Mikroarraytechnologie. Ziele sind u. a. das Design und die Untersuchung von multiplexfähigen selektiven und sensitiven Sonden für die Biomarkeranalytik, die Entwicklung von Methoden zur Charakterisierung der signalrelevanten Eigenschaften dieser Chromophor-Systeme und zur Charakterisierung von funktionellen Gruppen an Oberflächen und ihre Validierung sowie die Entwicklung und Bereitstellung von formatadaptierbaren, flexibel ersetzbaren
Standards für die fluoreszenzbasierte Multiparameteranalytik.
Increasing the information content from bioassays which requires robust and efficient strategies for the detection of multiple analytes or targets in a single measurement is an important field of research, especially in the context of meeting current security and health concerns. An attractive alternative to spectral multiplexing, which relies on fluorescent labels excitable at the same wavelength, yet sufficiently differing in their emission spectra or color presents lifetime multiplexing. For this purpose, we recently introduced a new strategy based on 'pattern-matching' in the lifetime domain, which was exemplary exploited for the discrimination between organic dyes and quantum dot labels revealing multi-exponential decay kinetics and allowed quantification of these labels. Meanwhile, we have succeeded in extending this lifetime multiplexing approach to nanometer-sized particle labels and probes absorbing and emitting in the visible (vis) and near-infrared (NIR) spectral region. Here, we present a first proof-of-principle of this approach for a pair of NIR-fluorescent particles. Each particle is loaded with a single organic dye chosen to display very similar absorption and emission spectra, yet different fluorescence decay kinetics. Examples for the lifetime-based distinction between pairs of these fluorescent nanoparticles in solution and in cells are presented. The results underline the potential of fluorescenc lifetime multiplexing in life science and bioanalysis.
The widespread use and acceptance of fluorescence techniques especially in regulated areas like medical diagnostics is closely linked to standardization concepts that guarantee and improve the comparability and reliability of fluorescence measurements. At the core of such concepts are dependable fluorescence standards that are preferably certified. The ever rising interest in fluorescence measurements in the near-infrared (NIR) spectral region renders the availability of spectral and intensity standards for this wavelength region increasingly important. This encouraged us to develop approaches to solid NIR standards based upon dye-doped polymers and assess their applicationrelevant properties in comparison to metal ion-doped glasses. The overall goal is here to provide inexpensive, easily fabricated, and robust internal and external calibration tools for a broad variety of fluorescence instruments ranging e.g. from spectrofluorometers over fluorescence microscopes to miniaturized fluorescence sensors.