Optically addressable spin defects in silicon carbide (SiC) are an emerging platform for quantum information processing compatible with nanofabrication processes and device control used by the ...semiconductor industry. System scalability towards large-scale quantum networks demands integration into nanophotonic structures with efficient spin-photon interfaces. However, degradation of the spin-optical coherence after integration in nanophotonic structures has hindered the potential of most colour centre platforms. Here, we demonstrate the implantation of silicon vacancy centres (V
) in SiC without deterioration of their intrinsic spin-optical properties. In particular, we show nearly lifetime-limited photon emission and high spin-coherence times for single defects implanted in bulk as well as in nanophotonic waveguides created by reactive ion etching. Furthermore, we take advantage of the high spin-optical coherences of V
centres in waveguides to demonstrate controlled operations on nearby nuclear spin qubits, which is a crucial step towards fault-tolerant quantum information distribution based on cavity quantum electrodynamics.
We investigate the magnetic field-dependent fluorescence lifetime of microdiamond powder containing a high density of nitrogen-vacancy centers. This constitutes a non-intensity quantity for robust, ...all-optical magnetic field sensing. We propose a fiber-based setup in which the excitation intensity is modulated in a frequency range up to 100MHz. The change in magnitude and phase of the fluorescence relative to B=0 is recorded where the phase shows a maximum in magnetic contrast of 5.8∘ at 13MHz. A lock-in amplifier-based setup utilizing the change in phase at this frequency shows a 100 times higher immunity to fluctuations in the optical path compared to the intensity-based approach. A noise floor of 20μT/Hz and a shot-noise-limited sensitivity of 0.95μT/Hz were determined.
Novel strategies to mimic mammalian extracellular matrix (ECM) in vitro are desirable to study cell behavior, diseases and new agents in drug delivery. Even though collagen represents the major ...constituent of mammalian ECM, artificial collagen hydrogels with characteristic tissue properties such as network size and stiffness are difficult to design without application of chemicals which might be even cytotoxic. In our study we investigate how high energy electron induced crosslinking can be utilized to precisely tune collagen properties for ECM model systems. Constituting a minimally invasive approach, collagen residues remain intact in the course of high energy electron treatment. Quantification of the 3D pore size of the collagen network as a function of irradiation dose shows an increase in density leading to decreased pore size. Rheological measurements indicate elevated storage and loss moduli correlating with an increase in crosslinking density. In addition, cell tests show well maintained viability of NIH 3T3 cells for irradiated collagen gels indicating excellent cellular acceptance. With this, our investigations demonstrate that electron beam crosslinked collagen matrices have a high potential as precisely tunable ECM-mimetic systems with excellent cytocompatibility.
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•Collagen hydrogels can be effectively tuned by reagent-free electron treatment to develop biomimetic ECM systems.•Properties of collagen hydrogels can be tuned by electron treatment influencing pore size and elastic behavior.•Electron beam treatment excellently maintains chemical integrity of collagen hydrogels.•Fibroblasts show high cytocompatibility with electron beam treated collagen hydrogels.
The rapid development of 3D printing using visible light as an irradiation source requires efficient visible light photoinitiators to realize a fast and reliable 3D printing process. Based on the ...photocleavage concept, a series of symmetric bifunctional photoinitiators comprising oxime‐ester moieties as latent initiation functionalities and conjugated carbazole as chromophores was synthesized. The impact of substitution position and the types of radicals on photophysical and photochemical behavior was investigated via experimental tests combined with quantum‐chemical calculations. The conjugated carbazole‐based oxime esters exhibit broad absorption bands from 250 to 400 nm and an interesting photobleaching property was observed during photolysis. Under 405 nm LED irradiation, the photoinitiation efficiency of the novel photoinitiators is comparable to that of the commercial visible light photoinitiator TPO. A vertical resolution of 50 μm was obtained when using oxime esters as photoinitiators in DLP 3D printing to fabricate delicate objects. The A‐π‐D‐π‐A core structures impart sufficient two‐photon cross sections (102–136 GM) to the oxime esters, enabling the construction of complex 3D microstructures of nanometer spatial resolution with two‐photon 3D printing technology. Notably, the threshold energy of the formulation containing 4d is lower than that of the commercial two‐photon resists IP−L. Also, the thermal stability of the PIs (>160 °C) is sufficient for daily storage.
Let′s go! Conjugated bifunctional carbazole‐based oxime esters can be used as efficient photoinitiators for 3D printing based on one‐ and two‐photon polymerization.
The purpose of our research was the development of Amphotericin B-loaded
gelling nanofibers for the treatment of keratomycosis. Different formulation strategies were applied to increase the drug load ...of the sparingly water-soluble Amphotericin B in electrospun Gellan Gum/Pullulan fibers. These include bile salt addition, encapsulation in poly(lactic-co-glycolic acid) (PLGA) nanoparticles and formation of a polymeric Amphotericin B polyelectrolyte complex. The Amphotericin B polyelectrolyte complex (AmpB-Eu L) performed best and was very effective against the fungal strain
. The complex was characterized in detail by attenuated total reflection infrared spectroscopy, X-ray powder diffraction, and differential scanning calorimetry. A heat induced stress test was carried out to ensure the stability of the polyelectrolyte complex. To gain information about the cellular tolerance of the developed polyelectrolyte complex a new, innovative multilayered-stratified human cornea cell model was used for determination of the cellular toxicity
. For a safe therapy, the applied ophthalmic drug delivery system has to be sterile. Sterilization by electron irradiation caused not degradation of pure Amphotericin B and also for the bile salt complex. Furthermore, the developed Amphotericin B polyelectrolyte complex was not degraded by the irradiation process. In conclusion, a new polyelectrolyte Amphotericin B complex has been found which retains the antifungal activity of the drug with sufficient stability against irradiation-sterilization induced drug degradation. Furthermore, in comparison with the conventional used eye drop formulation, the new AmpB-complex loaded nanofibers were less toxic to cornea cells
. Electrospinning of the Amphotericin B polyelectrolyte complex with Gellan Gum/ Pullulan leads to the formation of nanofibers with
gelling properties, which is a new and promising option for the treatment of keratomycosis.
Radiation-induced graft immobilization (RIGI) is a novel method for the covalent binding of substances on polymeric materials without the use of additional chemicals. In contrast to the well-known ...radiation-induced graft polymerization (RIGP), RIGI can use non-vinyl compounds such as small and large functional molecules, hydrophilic polymers, or even enzymes. In a one-step electron-beam-based process, immobilization can be performed in a clean, fast, and continuous operation mode, as required for industrial applications. This study proposes a reaction mechanism using polyvinylidene fluoride (PVDF) and two small model molecules, glycine and taurine, in aqueous solution. Covalent coupling of single molecules is achieved by radical recombination and alkene addition reactions, with water radiolysis playing a crucial role in the formation of reactive solute species. Hydroxyl radicals contribute mainly to the immobilization, while solvated electrons and hydrogen radicals play a minor role. Release of fluoride is mainly induced by direct ionization of the polymer and supported by water. Hydrophobic chains attached to cations appear to enhance the covalent attachment of solutes to the polymer surface. Computational work is complemented by experimental studies, including X-ray photoelectron spectroscopy (XPS) and fluoride high-performance ion chromatography (HPIC).
Abstract Colour centres in silicon carbide emerge as a promising semiconductor quantum technology platform with excellent spin-optical coherences. However, recent efforts towards maximising the ...photonic efficiency via integration into nanophotonic structures proved to be challenging due to reduced spectral stabilities. Here, we provide a large-scale systematic investigation on silicon vacancy centres in thin silicon carbide membranes with thicknesses down to 0.25 μm. Our membrane fabrication process involves a combination of chemical mechanical polishing, reactive ion etching, and subsequent annealing. This leads to highly reproducible membranes with roughness values of 3–4 Å, as well as negligible surface fluorescence. We find that silicon vacancy centres show close-to lifetime limited optical linewidths with almost no signs of spectral wandering down to membrane thicknesses of ~0.7 μm. For silicon vacancy centres in thinner membranes down to 0.25 μm, we observe spectral wandering, however, optical linewidths remain below 200 MHz, which is compatible with spin-selective excitation schemes. Our work clearly shows that silicon vacancy centres can be integrated into sub-micron silicon carbide membranes, which opens the avenue towards obtaining the necessary improvements in photon extraction efficiency based on nanophotonic structuring.
Abstract
The family of room temperature atomic scale magnetometers is currently limited to nitrogen-vacancy centers in diamond. However, nitrogen-vacancy centers are insensitive to strong off-axis ...magnetic fields. In this work, we show that the well-known TR12 radiative defect in diamond, exhibits strong optically detected magnetic resonance (ODMR) signal under optical saturation. We also demonstrate that the spin system responsible for the magnetic resonance is an excited triplet state that can be coherently controlled at room temperature on a single defect level. The high optically detected magnetic resonance contrast, which is maintained even for strong off-axis magnetic fields, suggests that TR12 centers can be used for vector magnetometry even at high field.
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