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Quantum dots (QDs) are semiconductor nanocrystals whose optical properties can be tuned by altering their size. By combining QDs with dyes we can make hybrid QD-dye systems exhibiting energy transfer (ET) between QDs and dyes, which is important in sensing and lighting applications. In conventional QDs that need a shell to passivate surface defects, ET usually proceeds through Förster resonance energy transfer (FRET) that requires significant spectral overlap between QD emission and dye absorbance, as well as large oscillator strengths of those transitions. This considerably limits the choice of dyes. In contrast, perovskite QDs do not require passivating shells for bright emission, which makes ET mechanisms beyond FRET accessible. This work explores the design of a CsPbBr 3 QD-dye system to achieve efficient ET from CsPbBr 3 QDs to dyes with dimethyl iminium binding groups where the close binding of dyes to CsPbBr 3 surface facilitates spatial wavefunction overlap. Using steady-state and time-resolved photoluminescence experiments, we demonstrate that efficient ET from CsPbBr 3 to dyes with minimal spectral overlap proceeds via the Dexter exchange-type mechanism, which overcomes the conventional restriction of spectral overlap that severely limits the tunability of these systems. This approach opens new avenues for QD-molecule hybrids for a wide range of applications, such as lighting., (© 2024 Wiley-VCH GmbH.)

Photocatalytic water splitting is a promising approach to generating sustainable hydrogen. However, the transport of photoelectrons to the catalyst sites, usually within ps-to-ns timescales, is much faster than proton delivery (∼μs), which limits the activity. Therefore, the acceleration of abstraction of protons from water molecules towards the catalytic sites to keep up with the electron transfer rate can significantly promote hydrogen production. The photobasic effect that is the increase in proton affinity upon excitation offers means to achieve this objective. Herein, we design photobasic carbon dots and identify that internal pyridinic N sites are intrinsically photobasic. This is supported by steady-state and ultrafast spectroscopic measurements that demonstrate proton abstraction within a few picoseconds of excitation. Furthermore, we show that in water, they form a unique four-level lasing scheme with optical gain and stimulated emission. The latter competes with photocatalysis, revealing a rather unique mechanism for efficiency loss, such that the stimulated emission can act as a toggle for photocatalytic activity. This provides additional means of controlling the photocatalytic process and helps the rational design of photocatalytic materials., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

The ever-increasing demands for data processing and storage will require seamless monolithic co-integration of electronics and photonics. Phase-change materials are uniquely suited to fulfill this function due to their dual electro-optical sensitivity, nonvolatile retention properties, and fast switching dynamics. The extreme size disparity however between CMOS electronics and dielectric photonics inhibits the realization of efficient and compact electrically driven photonic switches, logic and routing elements. Here, the authors achieve an important milestone in harmonizing the two domains by demonstrating an electrically reconfigurable, ultra-compact and nonvolatile memory that is optically accessible. The platform relies on localized heat, generated within a plasmonic structure; this uniquely allows for both optical and electrical readout signals to be interlocked with the material state of the PCM while still ensuring that the writing operation is electrically decoupled. Importantly, by miniaturization and effective thermal engineering, the authors achieve unprecedented energy efficiency, opening up a path towards low-energy optoelectronic hardware for neuromorphic and in-memory computing., (© 2022 The Authors. Advanced Science published by Wiley-VCH GmbH.)

Mn-doping in cesium lead halide perovskite nanoplatelets (NPls) is of particular importance where strong quantum confinement plays a significant role towards the exciton-dopant coupling. In this work, we report an immiscible bi-phasic strategy for post-synthetic Mn-doping of CsPbX 3 (X=Br, Cl) NPls. A systematic study shows that electron-donating oleylamine acts as a shuttle ligand to transport MnX 2 through the water-hexane interface and deliver it to the NPls. The halide anion also plays an essential role in maintaining an appropriate radius of Mn 2+ and thus fulfilling the octahedral factor required for the formation of perovskite crystals. By varying the thickness of parent NPls, we can tune the dopant incorporation and, consequently, the exciton-to-dopant energy transfer process in doped NPls. Time-resolved optical measurements offer a detailed insight into the exciton-to-dopant energy transfer process. This new approach for post-synthetic cation doping paves a way towards exploring the cation exchange process in several other halide perovskites at the polar-nonpolar interface., (© 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

It usually requires high temperature and high pressure to reform methanol with water to hydrogen with high turnover frequency (TOF). Here we show that hydrogen can be produced from alkaline methanol on a light-triggered multi-layer system with a very high hydrogen evolution rate up to ca. 1 μmol s -1 under the illumination of a standard Pt-decorated carbon nitride. The system can achieve a remarkable TOF up to 1.8×10 6  moles of hydrogen per mole of Pt per hour under mild conditions. The total turnover number (TTN) of 470 000 measured over 38 hours is among the highest reported. The system does not lead to any CO x emissions, hence it could feed clean hydrogen to fuel cells. In contrast to a slurry system, the proposed multi-layer system avoids particle aggregation and effectively uses light and Pt active sites. The performance is also attributed to the light-triggered reforming of alkaline methanol. This notable performance is a promising step toward practical light-driven hydrogen generation., (© 2021 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Perovskite nanocrystals (NCs) have revolutionized optoelectronic devices because of their versatile optical properties. However, controlling and extending these functionalities often requires a light-management strategy involving additional processing steps. Herein, we introduce a simple approach to shape perovskite nanocrystals (NC) into photonic architectures that provide light management by directly shaping the active material. Pre-patterned polydimethylsiloxane (PDMS) templates are used for the template-induced self-assembly of 10 nm CsPbBr 3 perovskite NC colloids into large area (1 cm 2 ) 2D photonic crystals with tunable lattice spacing, ranging from 400 nm up to several microns. The photonic crystal arrangement facilitates efficient light coupling to the nanocrystal layer, thereby increasing the electric field intensity within the perovskite film. As a result, CsPbBr 3 2D photonic crystals show amplified spontaneous emission (ASE) under lower optical excitation fluences in the near-IR, in contrast to equivalent flat NC films prepared using the same colloidal ink. This improvement is attributed to the enhanced multi-photon absorption caused by light trapping in the photonic crystal., (© 2020 The Authors. Published by Wiley-VCH GmbH.)

The concept of doping Mn 2+ ions into II-VI semiconductor nanocrystals (NCs) was recently extended to perovskite NCs. To date, most studies on Mn 2+ doped NCs focus on enhancing the emission related to the Mn 2+ dopant via an energy transfer mechanism. Herein, we found that the doping of Mn 2+ ions into CsPbCl 3 NCs not only results in a Mn 2+ -related orange emission, but also strongly influences the excitonic properties of the host NCs. We observe for the first time that Mn 2+ doping leads to the formation of Ruddlesden-Popper (R.P.) defects and thus induces quantum confinement within the host NCs. We find that a slight doping with Mn 2+ ions improves the size distribution of the NCs, which results in a prominent excitonic peak. However, with increasing the Mn 2+ concentration, the number of R.P. planes increases leading to smaller single-crystal domains. The thus enhanced confinement and crystal inhomogeneity cause a gradual blue shift and broadening of the excitonic transition, respectively., (© 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)

The growing demand for perovskite nanocrystals (NCs) for various applications has stimulated the development of facile synthetic methods. Perovskite NCs have often been synthesized by either ligand-assisted reprecipitation (LARP) at room temperature or by hot-injection at high temperatures and inert atmosphere. However, the use of polar solvents in LARP affects their stability. Herein, we report on the spontaneous crystallization of perovskite NCs in nonpolar organic media at ambient conditions by simple mixing of precursor-ligand complexes without application of any external stimuli. The shape of the NCs can be controlled from nanocubes to nanoplatelets by varying the ratio of monovalent (e.g. formamidinium + (FA + ) and Cs + ) to divalent (Pb 2+ ) cation-ligand complexes. The precursor-ligand complexes are stable for months, and thus perovskite NCs can be readily prepared prior to use. Moreover, we show that this versatile synthetic process is scalable and generally applicable for perovskite NCs of different compositions., (© 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)

Apart from its vital function as a redox cofactor, nicotinamide adenine dinucleotide (NAD + ) has emerged as a crucial substrate for NAD + -consuming enzymes, including poly(ADP-ribosyl)transferase 1 (PARP1) and CD38/CD157. Their association with severe diseases, such as cancer, Alzheimer's disease, and depressions, necessitates the development of new analytical tools based on traceable NAD + surrogates. Here, the synthesis, photophysics and biochemical utilization of an emissive, thieno[3,4-d]pyrimidine-based NAD + surrogate, termed N th AD + , are described. Its preparation was accomplished by enzymatic conversion of synthetic th ATP by nicotinamide mononucleotide adenylyltransferase 1 (NMNAT1). The new NAD + analogue possesses useful photophysical features including redshifted absorption and emission maxima as well as a relatively high quantum yield. Serving as a versatile substrate, N th AD + was reduced by alcohol dehydrogenase (ADH) to N th ADH and afforded th ADP-ribose ( th ADPr) upon hydrolysis by NAD + -nucleosidase (NADase). Furthermore, N th AD + was engaged in cholera toxin A (CTA)-catalyzed mono( th ADP-ribosyl)ation, but was found incapable in promoting PARP1-mediated poly( th ADP-ribosyl)ation. Due to its high photophysical responsiveness, N th AD + is suited for spectroscopic real-time monitoring. Intriguingly, and as an N7-lacking NAD + surrogate, the thieno-based cofactor showed reduced compatibility (i.e., functional similarity compared to native NAD + ) relative to its isothiazolo-based analogue. The distinct tolerance, displayed by diverse NAD + producing and consuming enzymes, suggests unique biological recognition features and dependency on the purine N7 moiety, which is found to be of importance, if not essential, for PARP1-mediated reactions., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Post-synthetic shape-transformation processes provide access to colloidal nanocrystal morphologies that are unattainable by direct synthetic routes. Herein, we report our finding about the ligand-induced fragmentation of CsPbBr 3 perovskite nanowires (NWs) into low aspect-ratio CsPbX 3 (X=Cl, Br and I) nanorods (NRs) during halide ion exchange reaction with PbX 2 -ligand solution. The shape transformation of NWs-to-NRs resulted in an increase of photoluminescence efficiency owing to a decrease of nonradiative decay rates. Importantly, we found that the perovskite NRs exhibit single photon emission as revealed by photon antibunching measurements, while it is not detected in parent NWs. This work not only reports on the quantum light emission of low aspect ratio perovskite NRs, but also expands our current understanding of shape-dependent optical properties of perovskite nanocrystals., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Self-assembly of nanoscale building blocks into ordered nanoarchitectures has emerged as a simple and powerful approach for tailoring the nanoscale properties and the opportunities of using these properties for the development of novel optoelectronic nanodevices. Here, the one-pot synthesis of CsPbBr 3 perovskite supercrystals (SCs) in a colloidal dispersion by ultrasonication is reported. The growth of the SCs occurs through the spontaneous self-assembly of individual nanocrystals (NCs), which form in highly concentrated solutions of precursor powders. The SCs retain the high photoluminescence (PL) efficiency of their NC subunits, however also exhibit a redshifted emission wavelength compared to that of the individual nanocubes due to interparticle electronic coupling. This redshift makes the SCs pure green emitters with PL maxima at ≈530-535 nm, while the individual nanocubes emit a cyan-green color (≈512 nm). The SCs can be used as an emissive layer in the fabrication of pure green light-emitting devices on rigid or flexible substrates. Moreover, the PL emission color is tunable across the visible range by employing a well-established halide ion exchange reaction on the obtained CsPbBr 3 SCs. These results highlight the promise of perovskite SCs for light emitting applications, while providing insight into their collective optical properties., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The colloidal synthesis and assembly of semiconductor nanowires continues to attract a great deal of interest. Herein, we describe the single-step ligand-mediated synthesis of single-crystalline CsPbBr 3 perovskite nanowires (NWs) directly from the precursor powders. Studies of the reaction process and the morphological evolution revealed that the initially formed CsPbBr 3 nanocubes are transformed into NWs through an oriented-attachment mechanism. The optical properties of the NWs can be tuned across the entire visible range by varying the halide (Cl, Br, and I) composition through subsequent halide ion exchange. Single-particle studies showed that these NWs exhibit strongly polarized emission with a polarization anisotropy of 0.36. More importantly, the NWs can self-assemble in a quasi-oriented fashion at an air/liquid interface. This process should also be easily applicable to perovskite nanocrystals of different morphologies for their integration into nanoscale optoelectronic devices., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

High-quality hybrid halide perovskite nanocrystals are fabricated through a simple, versatile, and efficient two-step process involving a dry step followed by a ligand-assisted liquid-phase exfoliation step. The emission wavelength of the resulting nanocrystals can be tuned either through composition by varying the halide content or by reducing their thickness., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We describe the simple, scalable, single-step, and polar-solvent-free synthesis of high-quality colloidal CsPbX 3 (X=Cl, Br, and I) perovskite nanocrystals (NCs) with tunable halide ion composition and thickness by direct ultrasonication of the corresponding precursor solutions in the presence of organic capping molecules. High angle annular dark field scanning transmission electron microscopy (HAADF-STEM) revealed the cubic crystal structure and surface termination of the NCs with atomic resolution. The NCs exhibit high photoluminescence quantum yields, narrow emission line widths, and considerable air stability. Furthermore, we investigated the quantum size effects in CsPbBr 3 and CsPbI 3 nanoplatelets by tuning their thickness down to only three to six monolayers. The high quality of the prepared NCs (CsPbBr 3 ) was confirmed by amplified spontaneous emission with low thresholds. The versatility of this synthesis approach was demonstrated by synthesizing different perovskite NCs., (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Red blood cells are "shaken" with a holographic optical tweezer array. The flow generated around cells due to the periodic optical forcing is measured with an optically trapped "detector" particle located in the cell vicinity. A signal-processing model that describes the cell's physical properties as an analog filter illustrates how cells can be distinguished from each other.

A Au-silica Janus particle is elevated along the laser beam axis in an optical trap. The propulsion mechanism is based on the local temperature gradient created around the particle due to the photothermal conversion of the gold-coated hemisphere. The height of the particle and its motion-direction are tuned by the nature and the concentration of the electrolytes in the medium., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Pyrite nanocrystals are currently considered as a promising material for large scale photovoltaic applications due to their non-toxicity and large abundance. While scalable synthetic routes for phase-pure and shape controlled colloidal pyrite nanocrystals have been reported, their use in solar cells has been hampered by the detrimental effects of their surface defects. Here, we report a systematic study of optical and electronic properties of pyrite nanocrystal thin films employing a series of different ligands varying both the anchor and bridging group. The effect of the ligands on the optical and electronic properties is investigated by UV-vis/NIR absorption spectroscopy, current voltage characteristic measurements and surface photovoltage spectroscopy. We find that the optical absorption is mainly determined by the anchor group. The absorption onset in the thin films shifts up to ∼100 meV to the red. This is attributed to changes in the dielectric environment induced by different anchors. The conductivity and photoconductivity, on the other hand, are determined by combined effects of anchor and bridging group, which modify the effective hopping barrier. Employing different ligands, the differential conductance varies over four orders of magnitude. The largest redshift and differential conductance are observed for ammonium sulfides and thiolated aromatic linkers. Pyridine and long chain amines, on the other hand, lead to smaller modifications. Our findings highlight the importance of surface functionalization and interparticle electronic coupling in the use of pyrite nanocrystals for photovoltaic devices., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Scope: Cardiovascular health is strongly influenced by diet. Zinc has antioxidant and anti-inflammatory properties but its long-term influence on vascular health at dietary intake levels relevant to the human population in developed countries has not been studied. We investigated the influence of suboptimal zinc intake in a Western-type diet on the development of vascular inflammation and arterial plaque in apoE knock-out (AEKO) mice., Methods and Results: Weanling AEKO and wild-type (WT) controls were given high saturated fat (21% w/w) and high cholesterol (0.15%) semi-synthetic diets containing 3 or 35 mg Zn/kg (AEKO and WT) or 8 mg Zn/kg (AEKO only) for over 6 months. AEKO mice on zinc intakes of 3 and 8 mg Zn/kg (suboptimal zinc) developed significantly (p < 0.05) more aortic plaque than AEKO mice consuming 35 mg Zn/kg (adequate zinc). Circulating levels of interleukin-1β, interleukin-6 and soluble vascular adhesion molecule-1 were significantly (p < 0.05) raised at the lowest zinc intake in AEKO mice, as compared to zinc-adequate controls. Plasma total cholesterol and total protein were also significantly (p < 0.05) increased at the lowest zinc intake., Conclusion: We propose that suboptimal dietary zinc intake raises circulating pro-atherogenic lipoprotein levels that promote vascular inflammation and enhance arterial plaque formation., (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Noble-metal-decorated colloidal semiconductor nanocrystals are currently receiving significant attention for photocatalytic hydrogen generation. A detailed knowledge of the charge-carrier dynamics in these hybrid systems under hydrogen generation conditions is crucial for improving their performance. Here, a transient absorption spectroscopy study is conducted on colloidal, Pt-decorated CdS nanorods addressing this issue. Surprisingly, under hydrogen generation conditions (i.e., in the presence of the hole-scavenger sodium sulfite), photoelectron transfer to the catalytically active Pt is slower than without the hole scavenger, where no significant hydrogen generation occurs. This unexpected behavior can be explained by different degrees of localization of the electron wavefunction in the presence and absence of holes on the nanorods, which modify the electron transfer rates to the Pt. The results show that solely optimizing charge transfer rates in photocatalytic nanosystems is no guarantee of improved performance. Instead, the collective Coulomb interaction-mediated electron-hole dynamics need to be considered., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Microfluidic jetting is a promising method to produce giant unilamellar phospholipid vesicles for mimicking living cells in biomedical studies. We have investigated the chemical composition of membranes of vesicles prepared using this approach by means of Raman scattering spectroscopy. The membranes of all jetted vesicles are found to contain residuals of the organic solvent decane used in the preparation of the initial planar membrane. The decane inclusions are randomly distributed over the vesicle surface area and vary in thickness from a few to several tens of nanometers. Our findings point out that the membrane properties of jetted vesicles may differ considerably from those of vesicles prepared by other methods and from those of living cells., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Scope: Zinc is implicated as an activator for bone formation, however, its influence on bone calcification has not been reported. This study examined how zinc regulates the bone matrix calcification in osteoblasts., Methods and Results: Two osteoblastic MC3T3-E1 cell subclones (SC 4 and SC 24 as high and low osteogenic differentiation, respectively) were cultured in normal osteogenic (OSM), Zinc deficient (Zn-, 1 μM), or adequate (Zn+, 15 μM) media up to 20 days. Cells (SC 4) were also supplemented with (50 μg/mL) or no ascorbic acid (AA) in combination with Zinc treatment. Zn- decreased collagen synthesis and matrix accumulation. Although AA is essential for collagen formation, its supplementation could not compensate for Zinc deficiency-induced detrimental effects on extracellular matrix mineralization. Zn- also decreased the medium and cell layer alkaline phosphatase ALP activity. This decreased ALP activity might cause the decrease of Pi accumulation in response to Zn-, as measured by von Kossa staining. Ca deposition in cell layers, measured by Alizarin red S staining, was also decreased by Zn(-) ., Conclusion: Our findings suggest that zinc deprivation inhibits extracellular matrix calcification in osteoblasts by decreasing the synthesis and activity of matrix proteins, type I collagen and ALP, and decreasing Ca and Pi accumulation. Therefore zinc deficiency can be considered as risk factor for poor extracellular matrix calcification., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Multispiked gold nanoparticles are required in large quantities for many fundamental studies and applications like (bio)sensing, but their preparation in high yield by the bottom-up chemical synthetic method is challenging. A water-based, non-'seed-mediated', straightforward method for the synthesis of gold nanoparticles with well-developed surface spikes is reported here. The yield of multispiked gold particles is very high (>90%). The method allows the tuning of the number and size of the spikes and the overall size of the particles, and hence the localized surface plasmon resonances of the particles over the broad spectral range in the visible and near-infrared. A mechanism for the evolution of twinned, sharp-tipped surface protrusions has been proposed based on systematic spectrophotometric and transmission electron microscopic studies, which were employed to elucidate the morphological features, structure, chemical composition, and optical properties of the multispiked gold nanoparticles., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Nanoparticles of noble metals belong to the most extensively studied colloidal systems in the field of nanoscience and nanotechnology. Due to continuing progress in the synthesis of nanoparticles with controlled morphologies, the exploration of unique morphology-dependent properties has gained momentum. Anisotropic features in nonspherical nanoparticles make them ideal candidates for enhanced chemical, catalytic, and local field related applications. Nonspherical plasmon resonant nanoparticles offer favorable properties for their use as analytical tools, or as diagnostic and therapeutic agents. This Review highlights morphology-dependent properties of nonspherical noble metal nanoparticles with a focus on localized surface plasmon resonance and local field enhancement, as well as their applications in various fields including Raman spectroscopy, fluorescence enhancement, analytics and sensing, photothermal therapy, (bio-)diagnostics, and imaging.

Although laser ablation (LA)-ICP-MS has been reported for the determination of metalloproteins separated by gel electrophoretic techniques (GE), systematic studies that define the conditions essential for successful measurements are still scarce. In this paper we present the results of our studies of basic conditions for the effective application of GE-LA-ICP-MS for the separation of metal-binding proteins, focusing on their stability during GE and post-separation gel treatment. The stability of metal-protein complexes (haemoglobin, myoglobin, superoxide dismutase, carbonic anhydrase, transferrin, albumin, cytochrome c) during GE is dependent on the nature of the metal-protein interaction and the principle of separation. We have observed that non-denaturing GE is a suitable separation technique for most metal-protein complexes (e.g. Zn in carbonic anhydrase and Fe in Tf and myoglobin were quantitatively recovered in a spiked liver cytosol), whereas separation by denaturing GE strongly impaired the stability of the complexes. Equally important is the post-separation treatment of the gel to enable successful detection of the metal. LA-ICP-MS requires drying of the gel without loss of protein-bound metal or cracking of the gel. This was successfully achieved using glycerol followed by heating. We demonstrate that staining of the gel prior to LA-ICP-MS using silver or Coomassie blue is not recommended, since most protein-bound metal is lost during the staining procedure. Furthermore it has been shown that only line scanning with a speed of less than 30 microm/s can reliably distinguish between lines 1 mm apart, while raster spot analysis carries the risk of misinterpretation due to contamination in/on inhomogeneous gels.