Matthias I. J. Stich

Luminescent Europium(III) Nanoparticles for Sensing and Imaging of Temperature in the Physiological Range

Europium(III) Nanoparticles are fabricated for sensing and imaging of physiological temperatures (see image). The material shows visible-light excitation, line-like emission, inertness to external perturbers (such as oxygen in air), and a dynamic range that covers temperatures encountered in medicine and (cellular) biology. The resolution is ±0.3 °C. The nanoparticles may also be incorporated into a (conceivably sprayable) sensor film.

Red- and Green-Emitting Iridium(III) Complexes for a Dual Barometric and Temperature-Sensitive Paint

A new dual luminescent sensitive paint for barometric pressure and temperature (T) is presented. The green-emitting iridium(III) complex [Ir(ppy)(2)(carbac)] (ppy=2-phenylpyridine; carbac=1-(9H-carbazol-9-yl)-5,5-dimethylhexane-2,4-dione) was applied as a novel probe for T along with the red-emitting complex [Ir(btpy)(3)], (btpy=2-(benzo[b]thiophene-2-yl)pyridine) which functions as a barometric (in fact oxygen-sensitive) probe. Both iridium complexes were dissolved in different polymer materials to achieve optimal responses. The probe [Ir(ppy)(2)(carbac)] was dispersed in gas-blocking poly(acrylonitrile) microparticles in order to suppress any quenching of its luminescence by oxygen. The barometric probe [Ir(btpy)(3)], in turn, was incorporated in a cellulose acetate butyrate film which exhibits good permeability for oxygen. The effects of temperature on the response of the oxygen probe can be corrected by simultaneous optical determination of T, as the poly(acrylonitrile) microparticles containing the temperature indicator are incorporated into the film. The phosphorescent signals of the probes for T and barometric pressure, respectively, can be separated by optical filters due to the approximately 75 nm difference in their emission maxima. The dual sensor is applicable to luminescence lifetime imaging of T and barometric pressure. It is the first luminescent dual sensor material for barometric pressure/T based exclusively on the use of Ir(III) complexes in combination with luminescence lifetime imaging.

Luminescent terbium and europium probes for lifetime based sensing of temperature between 0 and 70 °C

Organic europium (III) and terbium (III) complexes (refered to as Eu1, Eu2, and Tb-L1, Tb-L2, respectively) have been synthesized that display bright emission and small bandwidth. Tb-L1 and Tb-L2 show lifetimes in the order of almost 1 ms at room temperature, good color purity, and high relative photoluminescence quantum yields. This makes them excellent probes for sensing temperature via measurement of luminescence lifetime. Probes Eu1, Eu2, Tb-L1 and Tb-L2 were incorporated into various polymer matrices to give sensor films for use as temperature-sensitive paints (TSPs). Eu (III) complexes have the advantage of being effectively excited by purple light-emitting diodes with their peak wavelengths of 405 nm. All TSPs based on these europium and terbium probes display good sensitivities to temperature, in particular, TSP based on Tb-L1 and Tb-L2 can show temperature-lifetime sensitivities of −13.8 μs per °C and − 9.2 μs per °C, respectively. Assuming a precision of ± 1 μs in the determination of lifetime, this will enable temperature to be determined with a precision of around ± 0.1 °C. This temperature dependence is the highest one reported so far for lanthanide complexes.

Method for simultaneous luminescence sensing of two species using optical probes of different decay time, and its application to an enzymatic reaction at varying temperature

AbstractChemical sensing, imaging and microscopy based on the use of fluorescent probes has so far been limited almost exclusively to the detection of a single parameter at a time. We present a scheme that can overcome this limitation by enabling optical sensing of two parameter simultaneously and even at identical excitation and emission wavelengths of two probes provided (a) their decay times are different enough to enable two time windows to be recorded, and (b) the emission of the shorter-lived probe decays to below the detectable limit while that of the other still can be measured. We refer to this new scheme as the dual lifetime determination (DLD) method and show that it can be widely varied by appropriate choice of probes and experimental settings. DLD is demonstrated to work by sensing oxygen and temperature independently from each other by making use of two probes, one for oxygen (a platinum porphyrin dissolved in polystyrene), and one for temperature [a europium complex dissolved in poly(vinyl methylketone)]. DLD was applied to monitor the consumption of oxygen in the glucose oxidase-catalyzed oxidation of glucose at varying temperatures. The scheme is expected to have further applications in cellular assays and biophysical imaging. FigurePrinciple behind the dual lifetime determination (DLD) method

Fluorescence Sensing and Imaging Using Pressure-Sensitive Paints and Temperature-Sensitive Paints

Pressure-sensitive paints (PSPs) and temperature-sensitive paints (TSPs) are widely used in aerodynamic research and wind tunnel testing. Both systems are based on the incorporation of the respective indicators into a matrix polymer (often referred to as the “binder”) to be cast on the area of interest. Spatially resolved distributions of oxygen partial pressure (pO2) and temperature can be instantly visualized by making use of respective paints and appropriate techniques of fluorescence imaging.

New Plastic Microparticles and Nanoparticles for Fluorescent Sensing and Encoding

We report on the progress that has been made in the area of luminescence sensing and encoding by makinguse of microparticles and nanoparticles prepared from plastic materials. These are quite different fromparticles built up from metal sulfides (such as the so-called quantum dots, “Q-dots”; see Michaletet al., Science 307:538, 2005), other semiconductor materials, metalnanoparticles (mainly gold) (see DL Feldheim, CA Foss (eds) Metal Nanoparticles:Synthesis, Characterization, and Applications, p 338, Marcel Dekker, 2002), or glass andits modifications including certain sol–gels. Plastic nanoparticles may contain magnetic beads inorder to facilitate separation from the sample solution. All the particles described here are doped withfluorescent dyes, which is in contrast to particles where the material itself displays intrinsic luminescence.Unlike the case of Q-dots, the color of plastic beads can be varied to a wide extent irrespective oftheir size, as can be the decay times and even anisotropy. This, in fact, is a most attractive featureof such beads and makes them superior in many cases despite the undisputed utility of other types of particlesin certain fields.