Coating and functionalization of high density ion track structures by atomic layer deposition

In this study flexible TiO 2 coated porous Kapton membranes are presented having electron multiplication properties. 800 nm crossing pores were fabricated into 50 m thick Kapton membranes using ion track technology and chemical etching. Consecutively, 50 nm TiO 2 films were deposited i nto the pores of the Kapton membranes by atomic layer deposition using Ti( i OPr) 4 and water as precursors at 250 °C. The TiO 2 films and coated membranes were studied by scanning electro n microscopy (SEM), X - ray diffraction (XRD) and X - ray reflectometry (XRR). Au metal electrod e fabrication onto both sides of the coated foils was achieved by electron beam evaporation. The electron multipliers were obtained by joining 3 two coated membranes separated by a conductive spacer. The results show that electron multiplication can be achie ved using ALD - coated flexible ion track polymer foils

TiO2 Photocatalyzed Oxidation of Drugs Studied by Laser Ablation Electrospray Ionization Mass Spectrometry

In drug discovery, it is important to identify phase I metabolic modifications as early as possible to screen for inactivation of drugs and/or activation of prodrugs. As the major class of reactions in phase I metabolism is oxidation reactions, oxidation of drugs with TiO2 photocatalysis can be used as a simple non-biological method to initially eliminate (pro)drug candidates with an undesired phase I oxidation metabolism. Analysis of reaction products is commonly achieved with mass spectrometry coupled to chromatography. However, sample throughput can be substantially increased by eliminating pretreatment steps and exploiting the potential of ambient ionization mass spectrometry (MS). Furthermore, online monitoring of reactions in a time-resolved way would identify sequential modification steps. Here, we introduce a novel (time-resolved) TiO2-photocatalysis laser ablation electrospray ionization (LAESI) MS method for the analysis of drug candidates. This method was proven to be compatible with both TiO2-coated glass slides as well as solutions containing suspended TiO2 nanoparticles, and the results were in excellent agreement with studies on biological oxidation of verapamil, buspirone, testosterone, andarine, and ostarine. Finally, a time-resolved LAESI MS setup was developed and initial results for verapamil showed excellent analytical stability for online photocatalyzed oxidation reactions within the set-up up to at least 1h.Peer reviewe

Intercalation of Lithium Ions from Gaseous Precursors into beta-MnO2 Thin Films Deposited by Atomic Layer Deposition

LiMn2O4 is a promising candidate for a cathode material in lithium-ion batteries because of its ability to intercalate lithium ions reversibly through its three-dimensional manganese oxide network. One of the promising techniques for depositing LiMn2O4 thin-film cathodes is atomic layer deposition (ALD). Because of its unparalleled film thickness control and film conformality, ALD helps to fulfill the industry demands for smaller devices, nanostructured electrodes, and all-solid-state batteries. In this work, the intercalation mechanism of Li+ ions into an ALD-grown beta-MnO2 thin film was studied. Samples were prepared by pulsing (LiOBu)-Bu-t and H2O for different cycle numbers onto about 100 nm thick MnO2 films at 225 degrees C and characterized with X-ray absorption spectroscopy, X-ray diffraction, X-ray reflectivity, time-of-flight elastic recoil detection analysis, and residual stress measurements. It is proposed that forPeer reviewe

Role of ALD Al2O3 Surface Passivation on the Performance of p-Type Cu2O Thin Film Transistors

High-performance p- type oxide thin film transistors (TFTs) have great potential for many semiconductor applications. However, these devices typically suffer from low hole mobility and high off-state currents. We fabricated p-type TFTs with a phase-pure polycrystalline Cu2O semiconductor channel grown by atomic layer deposition (ALD). The TFT switching characteristics were improved by applying a thin ALD Al2O3 passivation layer on the Cu2O channel, followed by vacuum annealing at 300 degrees C. Detailed characterization by transmission electron microscopy-energy dispersive X-ray analysis and X-ray photoelectron spectroscopy shows that the surface of Cu2O is reduced following Al2O3 deposition and indicates the formation of a 1-2 nm thick CuAlO2 interfacial layer. This, together with field-effect passivation caused by the high negative fixed charge of the ALD Al2O3, leads to an improvement in the TFT performance by reducing the density of deep trap states as well as by reducing the accumulation of electrons in the semiconducting layer in the device off-state.Peer reviewe

X-ray ptychographic computed tomography at 16 nm isotropic 3D resolution

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Programming nanostructured soft biological surfaces by atomic layer deposition

Here, we present the first successful attempt to programme the surface properties of nanostructured soft biological tissues by atomic layer deposition (ALD). The nanopatterned surface of lotus leaf was tuned by 3-125 nm TiO2 thin films. The lotus/TiO2 composites were studied by SEM-EDX, XPS, Raman, TG-DTA, XRR, water contact angle and photocatalysis measurements. While we could preserve the superhydrophobic feature of lotus, we managed to add a new property, i.e. photocatalytic activity. We also explored how surface passivation treatments and various ALD precursors affect the stability of the sensitive soft biological tissues. As we were able to gradually change the number of nanopatterns of lotus, we gained new insight into how the hollow organic nanotubes on the surface of lotus influence its superhydrophobic feature

Nanofocusing of hard X-ray free electron laser pulses using diamond based Fresnel zone plates

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Surface Modification of Acetaminophen Particles by Atomic Layer Deposition

Organic solid pharmaceutical powders are used for the preparation of various drug dosage forms. Primary particles in powder form undergo several processing steps first in pharmaceutical formulations followed by pharmaceutical manufacturing to final dosage form of a drug. These unit operations involve both handling of powders in aqueous or solvent solutions and drying. There will be a probable rise for a demand for the different unit operations in the requirements of protecting the active pharmaceutical ingredient or challenges in powder handling. Besides pharmaceutical manufacturing, there are many biological interfaces where control of surface characteristics of pharmaceutical powders can improve the therapeutic response and bioavailability. In this work, we have modified acetaminophen particles with atomic layer deposition (ALD) by conformal nanometer scale coatings in a one-step coating process. According to the results, ALD comprising common chemistries for Al2O3, TiO2 and ZnO is shown to be a promising coating method for solid pharmaceutical powders. Acetaminophen does not undergo degradation during the ALD coating and maintains its stable polymorphic structure. The nanometer scale ALD coating can sustain the drug release. ALD oxide coated acetaminophen particles show different cytocompatibility assessed in in vitro intestinal Caco-2 cells.Peer reviewe