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Hepburn W.G.,University of Oxford | Batchelor-Mcauley C.,University of Oxford | Tschulik K.,University of Oxford | Kachoosangi R.T.,University of Oxford | And 4 more authors.
Sensors and Actuators, B: Chemical | Year: 2014

The electrochemical detection of organic capped CdSe nanoparticles is achieved down to the highly dilute concentration of 15 pM. Herein, electrode modification is undertaken either via a simple and fast adsorption methodology, or by direct dropcasting of the material. Importantly, the adsorption of the CdSe nanoparticles is evidenced at higher surface coverages by the direct measurement of the cadmium reduction signal. A lower analytical detection limit for the CdSe nanoparticles is enabled by the enhancement of the diffusional borax reduction signal on a gold electrode modified with the quantum dots. The presence of a non-electroactive layer on an electrode has been shown to alter the apparent electrochemical rate constant via modifying the solubility and mass-transport of an electroactive species adjacent to the electrochemical interface. In the present case the origin of the enhanced rate of reduction for borax is ascribed as being due to the presence of the non-electroactive organic capping agent. Hence, due to the ubiquitous nature of capping agents within the field of nano-chemistry, the methodology represents a facile and generally applicable detection route. © 2014 Elsevier B.V.


News Article | December 2, 2015
Site: phys.org

Distribution of the ceramic particles in the plastic visualized by electron microscopy. Credit: INM Digital X-ray systems have become a vital part of health care. The analog X-ray film of the past has been replaced by digital flat panel detectors. Today's detectors are sensitive but quite expensive and have limited resolution. Now, scientists collaborating in project HOP-X have succeeded in developing new materials for detectors: they embedded ceramic particles in a conductive plastic. The components of these "composite detectors" can be stirred into a solvent and then applied like paint by spraying. This means that, in future, it might be possible to manufacture X-ray detectors inexpensively and on a large scale with greater image resolution. These results were recently published in the magazine Nature Photonics. X-ray detectors consist of a scintillator layer and a photodiode. The scintillator layer converts X-rays into visible light which the photodiode absorbs. Such detectors are difficult to manufacture and expensive. Their resolution is limited because the signals received can interfere with each other. In order to manufacture X-ray detectors at lower cost, scientists from Siemens Healthcare GmbH, the INM –Leibniz Institute for New Materials, the CAN GmbH, the Universities of Erlangen and further partners took a new approach in the project HOP-X: they used materials developed for flexible solar cells and adapted them to the X-rays. For this purpose, the scientists at INM manufactured ceramic particles which light up when X-rays hit them. They embedded these in a conductive plastic. It converts the light into an electric current which is registered by the X-ray apparatus. The researchers investigated the composite material formed by the particles and the plastic. "We examined the samples with electron microscopy using thin layers cut out of the composite with ion beams," explains Tobias Kraus, Division Head for Structure Formation at INM. "The images we got show how the particles arrange inside the plastic at different mixing ratios. This enabled our partners to select the mixing ratios to make the most sensitive of X-ray detectors." The optimized materials yield high-resolution X-ray images already at a low radiation dosage. The results show that X-ray detectors made of new composite materials can fulfill the strict requirements of medical technology. The researchers are currently working on process techniques to allow the manufacture of larger detectors. More information: Patric Büchele et al. X-ray imaging with scintillator-sensitized hybrid organic photodetectors, Nature Photonics (2015). DOI: 10.1038/nphoton.2015.216


Sokolova N.V.,Moscow State University | Schotten T.,CAN GmbH | Berthold H.J.,Atotech Deutschland Gmbh | Thiem J.,University of Hamburg | Nenajdenko V.G.,Moscow State University
Synthesis (Germany) | Year: 2013

A series of novel, highly symmetrical phthalocyanines bearing eight peptide residues has been prepared by microwave-assisted Cu(I)-catalyzed 1,3-dipolar cycloaddition ('click' reaction). Water-soluble conjugates were obtained after straightforward deprotection of the amine and amide functionalities. The phthalocyanine conjugates were found to be nontoxic along the whole concentration range, which makes them promising photosensitizers for therapeutic use.


Berthold H.J.,University of Hamburg | Schotten T.,CAN GmbH | Hoffmann F.,University of Hamburg | Thiem J.,University of Hamburg
Synthesis | Year: 2010

The TBDPS protecting group was conveniently employed for the convergent synthesis of a highly soluble, fully protected octa-peripheral (op) substituted phthalocyanine (Pc). After facile deprotection, ex post modification of this full-fledged Pc scaffold by various linkers was successfully achieved. This strategy overcomes the downsides of widely established linear convergent approaches under harsh conditions, which are not only destructive to chemically sensitive substituents, but also detrimental to rapid diversification towards Pc libraries. © Georg Thieme Verlag Stuttgart.


Berthold H.J.,University of Hamburg | Thiem J.,University of Hamburg | Zaliani A.,ZBH Zentrum fur Bioinformatik | Schotten T.,CAN GmbH
Synthesis | Year: 2010

The de novo synthesis of an aromatic system via [2+2+2] alkyne cyclotrimerization provided access to a fluorenyl spiro-annelated-phthalic anhydride derivative. Its exceptional rigidity - originating from the orthogonally attached fluorenyl moiety - was confirmed by single-crystal X-ray analysis. The anhydride was used successfully as a precursor for the synthesis of a novel class of orthogonal spiro-annelated Zn-phthalocyanine, which has the potential to be used as a core for molecular architecture. © Georg Thieme Verlag Stuttgart.


Walczak R.,Wroclaw University of Technology | Werner K.,CAN GmbH | Niehaus J.,CAN GmbH
Procedia Engineering | Year: 2014

In this paper, for the first time results of works on novel miniature instrumentation for quantum rods (QR) fluorescence excitation and detection will be described. Presented solutions were developed to co-work with lab-on-a-chip (LOC) applications of QR fluorochromes in multichannel high sensitive fluorescence detection. © 2014 The Authors. Published by Elsevier Ltd.

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