Mato Knez

Enhanced Catalytic Activity for Methanol Electro‐oxidation of Uniformly Dispersed Nickel Oxide Nanoparticles—Carbon Nanotube Hybrid Materials

Highy crystalline NiO nanoparticles are uniformly grown on the walls of carbon nanotubes (CNTs) by atomic layer deposition (ALD) at moderate temperature.Their size and stoichiometry are controlled by the ALD process parameters. The obtained NiO/CNT hybrids exhibit excellent performance in the electro-oxidation of methanol.

Nanoporous Nitrogen‐Doped Titanium Dioxide with Excellent Photocatalytic Activity under Visible Light Irradiation Produced by Molecular Layer Deposition

cone, [13, 14] have been grown through MLD and those were mainly based on reactions between metal alkyl/chloride and glycol/glycerol. Given the great promise of MLD, it is highly demanded to develop new processing strategies for MLD. One important aspect for producing a larger range of organic–inorganic mixtures is the variability of compositions of the constituting organic and inorganic fractions of the resulting films. A limitation to rather short organic spacers, such as glycol, between the metal ions is a bottleneck for the synthesis of films with a broader range of organic–inorganic

Efficient focusing of 8 keV X-rays with multilayer Fresnel zone plates fabricated by atomic layer deposition and focused ion beam milling

The fabrication and performance of multilayer Al2O3/Ta2O5 Fresnel zone plates in the hard X-ray range and a discussion of possible future developments considering available materials are reported.

Ferritin-mediated siRNA delivery and gene silencing in human tumor and primary cells

We demonstrate a straightforward method to encapsulate siRNA into naturally available and unmodified human apoferritin. The encapsulation into apoferritin is independent of the sequence of the siRNA and provides superior protection for those sensitive molecules. High efficiency in transfection can be achieved in human tumorigenic cells, human primary mesenchymal stem cells (hMSC) and peripheral blood mononuclear cells (PBMCs). In contrast to Lipofectamine, highly effective gene silencing can be achieved with ferritin as the delivery agent in both tumor cells and PBMCs at low siRNA concentrations (10xa0nM). As an endogenous delivery agent, apoferritin does not induce immune activation of T- and B-cells in human PBMCs. Apoferritin shows intrinsic anti-inflammatory effects and apoferritin-mediated delivery shows a preference for immune-activated T- and B-cells, a natural selectivity which may turn useful for drug delivery in case of infections or inflammatory diseases.

Multilayer Fresnel zone plates for high energy radiation resolve 21 nm features at 1.2 keV

X-ray microscopy is a successful technique with applications in several key fields. Fresnel zone plates (FZPs) have been the optical elements driving its success, especially in the soft X-ray range. However, focusing of hard X-rays via FZPs remains a challenge. It is demonstrated here, that two multilayer type FZPs, delivered from the same multilayer deposit, focus both hard and soft X-rays with high fidelity. The results prove that these lenses can achieve at least 21 nm half-pitch resolution at 1.2 keV demonstrated by direct imaging, and sub-30 nm FWHM (full-pitch) resolution at 7.9 keV, deduced from autocorrelation analysis. Reported FZPs had more than 10% diffraction efficiency near 1.5 keV.

Efficient and controllable vapor to solid doping of the polythiophene P3HT by low temperature vapor phase infiltration

Efficient doping of organic semiconductors is an important prerequisite for the fabrication of high performance organic electronic devices. In this work, we describe a novel single precursor low-temperature (70 °C) vapor phase infiltration (VPI) process to dope poly(3-hexyl)thiophene (P3HT). The infiltration is performed with the metal containing atomic layer deposition (ALD) precursor MoCl5. The conductivities of the polymer are assessed with four-point probe measurements and showed significant enhancement by up to 5 orders of magnitude, confirming the efficiency of the VPI process. The chemical changes resulting from the infiltration of P3HT are characterized by applying UV-Vis-NIR, Raman spectroscopy, and FTIR. The crystalline state of the material is analyzed by X-ray diffraction (XRD). SEM micrographs and AFM images show that the morphologies of the samples before and after the MoCl5 infiltration process do not seriously change. TEM images of cross-sections of the thin film clearly show that the vapor phase infiltration process results in the incorporation of Mo into the bulk of the polymer.

Comparison of two endogenous delivery agents in cancer therapy: Exosomes and ferritin

Exosomes and ferritin: Two biomacromolecules from our human bodies both draw increasing interest for advanced drug delivery due to their endogenous origin and their morphology, the cage-like structures. They possess perfect naturally designed structures for loading and shielding of cargo. Their intrinsic biological functions enable a natural delivery of the load and specific targeting. More and more evidences point towards the evolution of a new era of drug delivery strategies with exosomes and ferritin, even for potential personalized therapy. This review focuses on the advantages as well as limits of exosomes and ferritin as endogenous carriers for cancer therapy. We compare their structure-specific cargo loading and their intrinsic cancer-related biological functions. Remaining challenges and promising perspectives for future development to use these two endogenous agents are discussed.

Semi-artificial and bioactive ferroxidase with nanoparticles as the active sites

Light-chain apoferritin lacks ferroxidase activity, which can be supplemented with Pt-nanoparticles. The hybrid bioinorganic nanoparticle outperforms its heavy-chain pendant in terms of ferroxidase activity, mineralization ability and inhibition resistance. Being active in a cellular environment it regulates the iron homeostasis.

Highly reflective polymeric substrates functionalized utilizing atomic layer deposition

Reflective surfaces are one of the key elements of solar plants to concentrate energy in the receivers of solar thermal electricity plants. Polymeric substrates are being considered as an alternative to the widely used glass mirrors due to their intrinsic and processing advantages, but optimizing both the reflectance and the physical stability of polymeric mirrors still poses technological difficulties. In this work, polymeric surfaces have been functionalized with ceramic thin-films by atomic layer deposition. The characterization and optimization of the parameters involved in the process resulted in surfaces with a reflection index of 97%, turning polymers into a real alternative to glass substrates. The solution we present here can be easily applied in further technological areas where seemingly incompatible combinations of polymeric substrates and ceramic coatings occur.

High-resolution high-efficiency multilayer Fresnel zone plates for soft and hard x-rays

X-ray microscopy enables high spatial resolutions, high penetration depths and characterization of a broad range of materials. Calculations show that nanometer range resolution is achievable in the hard X-ray regime by using Fresnel zone plates (FZPs) if certain conditions are satisfied. However, this requires, among other things, aspect ratios of several thousands. The multilayer (ML) type FZPs, having virtually unlimited aspect ratios, are strong candidates to achieve single nanometer resolutions. Our research is focused on the fabrication of ML-FZPs which encompasses deposition of multilayers over a glass fiber via the atomic layer deposition (ALD), which is subsequently sliced in the optimum thickness for the X-ray energy by a focused ion beam (FIB). We recently achieved aberration free imaging by resolving 21 nm features with an efficiency of up to 12.5 %, the highest imaging resolution achieved by an ML-FZP. We also showed efficient focusing of 7.9 keV X-rays down to 30 nm focal spot size (FWHM). For resolutions below ~10 nm, efficiencies would decrease significantly due to wave coupling effects. To compensate this effect high efficiency, low stress materials have to be researched, as lower intrinsic stresses will allow fabrication of larger FZPs with higher number of zones, leading to high light intensity at the focus. As a first step we fabricated an ML-FZP with a diameter of 62 μm, an outermost zone width of 12 nm and 452 active zones. Further strategies for fabrication of high resolution high efficiency multilayer FZPs will also be discussed.