Karl David Wegner

Karl David Wegner
Bundesanstalt für Materialforschung und -prüfung | BAM · Department of Analytical Chemistry (Dpt.1)

PhD in Physics

About

55
Publications
7,443
Reads
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2,308
Citations
Additional affiliations
July 2018 - July 2019
Bundesanstalt für Materialforschung und -prüfung
Position
  • Fellow

Publications

Publications (55)
Cover Page
Full-text available
Nanocluster in a jewel case: A single, atomically precise gold nanocluster (Au25) has been incorporated inside bovine serum albumin protein. A striking increase in Au25‐BSA NIR‐II photoluminescence was observed as compared to Au25. The results reveal the intricate role of protein rigidification and the involvement of different excited states in the...
Article
Atomically precise gold nanoclusters are a fascinating class of nanomaterials that exhibit molecule‐like properties and have outstanding photoluminescence (PL). Their ultrasmall size, molecular chemistry, and biocompatibility make them extremely appealing for selective biomolecule labeling in investigations of biological mechanisms at the cellular...
Article
The synthesis of two new families of ZnSe magic-sized clusters (MSCs) is achieved using the thiol ligand 1-dodecanethiol in a simple one-pot heat-up approach. The sizes of the MSCs are controlled with the thiol ligand concentration and reaction temperature.
Cover Page
Full-text available
A detailed description of photophysical properties of NIR-II emitting probe and their use for pseudo-3D views of vascular blood vessels.
Article
Light-emitting nanoparticles like semiconductor nanocrystals (termed quantum dots, QDs) are promising candidates for biosensing and bioimaging applications based on their bright and stable photoluminescent properties. As high-quality QDs are often synthesized in organic solvents, strategies needed to be developed to render them water-dispersible wi...
Article
The influence of solvent polarity and surface ligand rigidification on the SWIR emission profile of gold nanoclusters with an anistropic surface was investigated. A strong enhancement of the SWIR emis- sion band at 1200 nm was observed when measuring in different local environments: in solution, in polymer composites, and in solids. SWIR in vivo im...
Article
Full-text available
Most studies about the interaction of nanoparticles (NPs) with cells have focused on how the physicochemical properties of NPs will influence their uptake by cells. However, much less is known about their potential excretion from cells. However, to control and manipulate the number of NPs in a cell, both cellular uptake and excretion must be studie...
Preprint
Full-text available
Atomically precise gold nanoclusters (Au NCs) are a fascinating class of nanomaterials that exhibit molecule-like properties and have outstanding photoluminescence (PL), which is highly dependent on their structure and chemical environment. Their ultrasmall size, molecular chemistry, and biocompatibility make them extremely appealing for selective...
Article
Full-text available
Luminescent solar concentrators (LSC) allow to obtain renewable energy from building integrated photovoltaic systems. As promising efficient and long‐term stable LSC fluorophores semiconductor nanocrystals like quantum dots (QDs) with size and composition tunable optoelectronic properties have recently emerged. The most popular II/VI or IV/VI semic...
Article
Full-text available
Quantum dots (QDs) are colloidal fluorescent semiconductor nanocrystals with exceptional optical properties. Their widespread use, particularly in light-emitting diodes (LEDs), displays, and photovoltaics, is questioning their potential toxicity. The most widely used QDs are CdSe and CdTe QDs, but due to the toxicity of cadmium (Cd), their use in e...
Conference Paper
We present a method of high resolution, non-invasive, in vivo vascular imaging obtained using watersoluble and bright SWIR-emitting gold nanoclusters presenting an anisotropic surface charge combined with SWIR detection and Monte Carlo processing of the images. We applied this approach to quantify vessel complexity in mice presenting vascular disor...
Preprint
Full-text available
Eu$^{2+}$ is used to replace toxic Pb$^{2+}$ in metal halide perovskite nanocrystals (NCs). The synthesis implies injection of cesium oleate into a solution of europium (II) bromide at an experimentally determined optimum temperature of 130C and a reaction time of 60s. Structural analysis indicates the formation of spherical CsEuBr$_3$ nanoparticle...
Article
Full-text available
Boron neutron capture therapy (BNCT) is a radiotherapeutic modality based on the nuclear capture of slow neutrons by stable 10B atoms followed by charged particle emission that inducing extensive damage on a very localized level (<10 μm). To be efficient, a sufficient amount of 10B should accumulate in the tumor area while being almost cleared from...
Article
Full-text available
Time-gated Förster resonance energy transfer (TG-FRET) between Tb complexes and luminescent semiconductor quantum dots (QDs) provides highly advantageous photophysical properties for multiplexed biosensing. Multiplexed Tb-to-QD FRET immunoassays possess a large potential for in vitro diagnostics, but their performance is often insufficient for thei...
Article
Full-text available
A facile hydrothermal method to synthesize water-soluble copper indium sulfide (CIS) nanocrystals (NCs) at 150 °C is presented. The obtained samples exhibited three distinct photoluminescence peaks in the red, green and blue spectral regions, corresponding to three size fractions, which could be separated by means of size-selective precipitation. W...
Article
Full-text available
In the blossoming field of Cd-free semiconductor quantum dots (QDs), ternary I-III-VI QDs have received increasing attention due to the ease of the environmentally friendly synthesis of high-quality materials in water, their high photoluminescence (PL) quantum yields (QYs) in the red and near infrared (NIR) region, and their inherently low toxicity...
Article
A simple NIR-II emitting water-soluble system has been developed and applied in vitro and in vivo. In vitro, the fluorophore quickly accumulated in 2D and 3D cell cultures and rapidly reached the tumor in rodents, showing high NIR-II contrast for up to one week. This very efficient probe possesses all the qualities necessary for translation to the...
Article
We synthesized a generation of water-soluble, atomically precise gold nanoclusters (Au NCs) with anisotropic surface containing short dithiol pegylated chain (AuMHA/TDT). These AuMHA/TDT exhibit a high brightness (QY∼6%) in the shortwave infrared (SWIR) spectrum with a detection above 1250 nm. Furthermore, they show an extended half-life in blood (...
Preprint
Full-text available
We present here a new approach for non-invasive high resolution whole-body vascular imaging in depth by combining water-soluble and bright SWIR-emitting gold nanoclusters revealing an anisotropic surface charge with Monte Carlo image processing of the images. We applied and validated this approach to quantify vessel complexity in transgenic mice pr...
Article
Eu²⁺ is used to replace toxic Pb²⁺ in metal halide perovskite nanocrystals (NCs). The synthesis implies injection of cesium oleate into a solution of europium (ii) bromide at an experimentally determined optimum temperature of 130 °C and a reaction time of 60 s. Structural analysis indicates the formation of spherical CsEuBr3 nanoparticles with a m...
Article
Many attempts have been made to synthesize cadmium-free quantum dots (QDs) using nontoxic materials, while preserving their unique optical properties. Despite impressive advances, gaps in knowledge of their intracellular fate, persistence and excretion from the targeted cell or organism still exist, precluding clinical applications. In this study,...
Article
Full-text available
With the goal to improve their photostability, InP-based QDs are passivated with three types of inorganic shells, namely (i) a gradient ZnSexS1−x shell, (ii) an additional ZnS shell on top of the gradient shell with two different thicknesses (core/shell/shell, CSS), (iii) an alumina coating on top of ZnS. All three systems have photoluminescence qu...
Article
Incorporating anisotropic surface charges on atomically precise gold nanoclusters (Au NCs) led to a strong absorption in the nearinfrared and could generate the formation of self-assembled Au NCs exhibiting an intense absorption band at ~1000 nm. This surface modification showed a striking enhancement of the photoluminescence in the Shortwave Infra...
Article
Due to their unique optical properties, quantum dots (QDs) are used in a number of optoelectronic devices and are forecasted to be used in the near future for biomedical applications. The most popular QD composition consists of cadmium selenide (CdSe) or cadmium telluride (CdTe), which has been shown to pose health risks due to the release of toxic...
Article
With the goal to tune the emission properties of colloidal InP quantum dots, the incorporation of Ga was explored. Unexpectedly, depending on the nature of the gallium precursor the photoluminescence...
Article
We demonstrate that cadmium-free core–shell CuInS2/ZnS quantum dots (QDs) are very efficient and robust visible-light absorbing photosensitizers for photocatalytic hydrogen production in a fully aqueous solution when associated with a molecular catalyst, a cobalt tetraazamacrocyclic complex. In the presence of ascorbate as a sacrificial electron do...
Article
Colloidal chalcopyrite-type nanocrystals M+M3+E2 (M+ = Cu, Ag; M3+ = In, Fe; E = S, Se) are an emerging class of materials used in energy conversion systems, owing to their high absorption coefficients, non-toxicity and appropriate band gaps. Their properties can be tuned by varying their size and composition, and they are characterized by peculiar...
Article
Full-text available
Compact and functional nanoparticle-antibody conjugates are of paramount importance for the development of quantum dot (QD)-based immunoassays. Here, we present a simple strategy to directly conjugate IgG, F(ab')2, and Fab antibodies via their endogenous disulfide groups directly to the inorganic ZnS shell of compact penicillamine-coated QDs. The f...
Article
Biosensors based on the combination of semiconductor quantum dots (QDs) and Förster resonance energy transfer (FRET) have demonstrated many advantages for simple, fast, sensitive, and multiplexed diagnostics. However, the implementation of QDs as functional standard materials into homogeneous (single-step) FRET immunoassays has not yet been accompl...
Article
A novel two-step approach for quantum dot (QD) functionalization and bioconjugation is presented, which yields ultra-compact, stable, and highly luminescent antibody-QD conjugates suitable for use in FRET immunoassays. Hydrophobic InPZnS/ZnSe/ZnS (emission wavelength: 530 nm), CdSe/ZnS (605 nm), and CdSeTe/ZnS (705 nm) QDs were surface functionaliz...
Article
Full-text available
The integration of semiconductor quantum dots (QDs) into homogeneous Förster resonance energy transfer (FRET) immunoassay kits for clinical diagnostics can provide significant advantages concerning multiplexing and sensitivity. Here we present a facile and functional QD-antibody conjugation method using three commercially available QDs with differe...
Article
Full-text available
The importance of microRNA (miRNA) dysregulation for the development and progression of diseases and the discovery of stable miRNAs in peripheral blood have made these short-sequence nucleic acids next-generation biomarkers. Here we present a fully homogeneous multiplexed miRNA FRET assay that combines careful biophotonic design with various RNA hy...
Article
Der einfache, empfindliche und selektive Nachweis von kurzsequenziellen MicroRNAs ist sehr anspruchsvoll. In ihrer Zuschrift (DOI: 10.1002/ange.201504887) präsentieren N. Hildebrandt und Mitarbeiter einen Einzelschritt-FRET-Assay für den Multiplex-Nachweis verschiedener MicroRNAs. Der Micro-RNA-Test für die klinische Diagnostik kombiniert sorgfälti...
Thesis
Förster resonance energy transfer (FRET) is a non-radiative energy transfer from a donor to an acceptor in close proximity. Due to its extremely sensitive distance dependence in the 1 – 20 nm range, FRET plays an important role in nanobiotechnology. Thereby FRET can be used as signal transduction system but also for the distance estimation between...
Article
Full-text available
Semiconductor quantum dots (QDs) have become important fluorescent probes for in vitro and in vivo bioimaging research. Their nanoparticle surfaces for versatile bioconjugation, their adaptable photophysical properties for multiplexed detection, and their superior stability for longer investigation times are the main advantages of QDs compared to o...
Article
Both upconverting nanoparticles (UCNPs) and semiconductor quantum dots (QDs) have revolutionized optical biosensing because of their unique photophysical properties. However, their outstanding photostability, near-infrared (NIR) excitability, and colour tunability have never been combined for homogeneous mix-and-measure FRET (Förster resonance ener...
Article
Full-text available
Fluorescence imaging of cells and subcellular compartments is an essential tool to investigate biological processes and to evaluate the development and progression of diseases. In particular, protein-protein interactions can be monitored by Förster resonance energy transfer (FRET) between two proximal fluorophores that are attached to specific reco...
Article
Optical quantification of several biomarkers at very low concentrations and nanometric distances has become an important requirement for many biosensing applications. Förster resonance energy transfer (FRET) and, in particular, luminescent terbium complex (LTC)-based FRET, is a valuable tool for sensitive and versatile multiplexed FRET. Here, we re...
Article
A new class of optoelectronic nanodevices consisting of 0D semiconductor nanocrystals and 2D single graphene layers is attracting much attention. In particular, such a system may be used to investigate and control the transfer of energy and charge in low-dimensional systems. To this end, the fluorescence dynamics of individual colloidal quantum dot...
Article
Luminescent semiconductor quantum dots (QDs) play an important role in optical biosensing and, in particular, in FRET (Förster resonance energy transfer)-based luminescent probes. The QD materials that form the basis for these probes are in actuality quite heterogeneous and consist of different types of QDs with variations in material compositions,...
Article
Luminescent lanthanide labels (LLLs) and semiconductor quantum dots (QDs) are two very special classes of (at least partially) inorganic fluorophores, which provide unique properties for Förster resonance energy transfer (FRET). FRET is an energy-transfer process between an excited donor fluorophore and a ground-state acceptor fluorophore in close...
Article
Semiconductor quantum dot nanocrystals (QDs) for optical biosensing applications often contain thick polyethylene glycol (PEG)-based coatings in order to retain the advantageous QD properties in biological media such as blood, serum or plasma. On the other hand, the application of QDs in Förster resonance energy transfer (FRET) immunoassays, one of...
Article
A myriad of quantum dot (QD) biosensor examples have emerged from the literature over the last decade, but despite their photophysical advantages QDs have yet to find acceptance as standard fluorescent reagents in clinical diagnostics. Lack of reproducible, stable and robust immunoassays using easily-prepared QD-antibody conjugates has historically...
Article
Full-text available
The first example of an activated phosphonated trifunctional chelate (TFC) is presented, which combines a non-macrocyclic coordination site for lanthanide coordination based on two aminobis-methylphosphonate coordinating arms, a central bispyrazolylpyridyl antenna and an N-hydroxysuccinimide ester in para position of the central pyridine as an acti...
Conference Paper
Full-text available
Figure 5-The black line is the reference luminescence decay curve for the pure Tb decay curve without any influence of QD655. After adding different amounts of QD655 the donor decay curves (Ch D) show a systematic decrease in intensity and lifetime with increasing acceptor concentration. This is a result of donor fluorescence quenching by FRET. The...
Article
In clinical diagnostics, homogeneous time-resolved (TR) FRET immunoassays are used for fast and highly sensitive detection of biomarkers in serum samples. The most common immunoassay format is based on europium chelate or cryptate donors and allophycocyanin acceptors. Replacing europium donors with terbium complexes and the acceptors with QDs offer...
Article
The unique photophysical properties of semiconductor quantum dot (QD) bioconjugates offer many advantages for active sensing, imaging, and optical diagnostics. In particular, QDs have been widely adopted as either donors or acceptors in Förster resonance energy transfer (FRET)-based assays and biosensors. Here, we expand their utility by demonstrat...
Article
Semiconductor nanocrystals (quantum dots - QDs) possess unique photophysical properties that make them highly interesting for many biochemical applications. Besides their common use as fluorophores in conventional spectroscopy and microscopy, QDs are well-suited for studying Förster resonance energy transfer (FRET). Size-dependent broadband absorpt...

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Projects (3)
Project
In this Special Issue, manuscripts are invited, which are devoted to the application of FRET for designing various types of sensors. Both reviews and original research articles will be published. Reviews should provide a critical overview of the current state-of-the-art in a particular application field, such as in vitro diagnostics, food safety and quality control or environmental pollution. Critical overviews about the use of a specific fluorophores, such as semiconductor nanocrystals or other nanoparticles in FRET-based biosensing applications, are also of interest. Original research papers that present new FRET-based sensor designs and/or fundamental studies with potential relevance to biosensing are also welcome. Dr. Karl David Wegner Guest Editor Link: http://www.mdpi.com/journal/biosensors/special_issues/FRET_biosensors
Project
I am interested in all sorts of energy transfer based diagnostic assay development. currently my group is developing BRET and TR-FRET and smFRET based biosensor for food safety and in vitro diagnostics purposes