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© 2018 Stephanie Seré et al. Mesoporous silica nanoparticles (MSNPs) are gaining a large interest in the field of medical and biomedical applications due to their biodegradability and high loading capacity as a carrier. In this work, a simple synthesis and functionalization procedure is reported, which allows tuning the nanoparticle properties, functionalization, and biodegradability. Variations in the synthesis procedure are introduced, including temperature, concentration of catalyst, and surface functionalization. These samples are characterized and afterwards degraded in phosphate buffered saline (PBS) to determine their degradation kinetics. The amount of degraded material is colorimetrically determined, using an optimized protocol based on molybdenum blue chemistry. It is shown that the degradability of the nanoparticles increased with decreasing synthesis temperatures, lower amounts of catalyst, and higher concentrations of nanoparticles. Surface functionalization alters the degradation kinetics as well, rendering amino-functionalized nanoparticles the fastest degradation behavior, followed by carboxylated and nonfunctionalized nanoparticles. From these results, it can be concluded that the degradation rate of MSNPs can be varied from a few hours to several days by small changes in the synthesis procedure. Moreover, the degradation behavior is strongly dependent on the nanoparticle growth rate. ispartof: JOURNAL OF NANOMATERIALS vol:2018 status: published

The linear and nonlinear optical properties of metal nanoparticles are highly tunable by variation of parameters such as particle size, shape, composition, and environment. To fully exploit this tunability, however, quantitative information on nonlinear absorption cross sections is required, as well as a sufficient understanding of the physical mechanism underlying these nonlinearities. In this work, we present a detailed and systematic investigation of the wavelength-dependent nonlinear optical properties of Ag nanoparticles embedded in a glass host, in which the most important parameters determining the nonlinear behavior of the system are characterized. This allows a proper quantification of absorption cross sections and elucidation of the excitation mechanism. Based on small-angle X-ray scattering measurements average particle diameters of 3 and 17 nm are estimated for the studied samples. The nonlinear optical properties of the nanoparticle-glass composite are studied in an extended wavelength range with the open aperture z-scan technique. The experiments reveal a strong dependence of the nonlinear optical response on the excitation wavelength. Based on the wavelength-dependent response, excited-state absorption is determined as the excitation mechanism of the nanoparticles. Electromagnetic simulations demonstrate that the contributions from electric field enhancement and plasmonic coupling between the particles in the diluted glasses are limited, which implies that the very high two-photon absorption cross section at 460 nm ((6.9 ± 1.6) × 106 GM for the 3 nm particles and (19.5 ± 2.2) × 109 GM for the 17 nm particles) is an intrinsic property. In addition, irradiance-dependent measurements elucidate the role of saturation of the excited-state absorption process on the observed nonlinearities.

This Algorithm Theoretical Basis Document (ATBD)describes in detail the methodology used to producethe third collection of the 100m Land Cover product, the global annual maps for the period 2015-2019, that was released under the global component of the Copernicus Land Monitoring Service. The methodology covers the retrieval and pre-processing of Earth Observation satellite (PROBA-V) observations, the calculation of metrics, the main classification, the regression forthe versatile cover fraction layers, the time series break detectionand so on. Next to the detailed ATBD, a summary Product User Manual describes the product (methodology, quality, contents and format) and Validation Report(s) provide more details on the validation and quality of the product.

Nanomaterials are being extensively produced and applied in society. Human and environmental exposures are, therefore, inevitable and so increased attention is being given to nanotoxicity. While silica nanoparticles (NP) are one of the top five nanomaterials found in consumer and biomedical products, their toxicity profile is poorly characterized. In this study, we investigated the toxicity of silica nanoparticles with diameters 20, 50 and 80 nm using an in vivo zebrafish platform that analyzes multiple endpoints related to developmental, cardio-, hepato-, and neurotoxicity. Results show that except for an acceleration in hatching time and alterations in the behavior of zebrafish embryos/larvae, silica NPs did not elicit any developmental defects, nor any cardio- and hepatotoxicity. The behavioral alterations were consistent for both embryonic photomotor and larval locomotor response and were dependent on the concentration and the size of silica NPs. As embryos and larvae exhibited a normal touch response and early hatching did not affect larval locomotor response, the behavior changes observed are most likely the consequence of modified neuroactivity. Overall, our results suggest that silica NPs do not cause any developmental, cardio- or hepatotoxicity, but they pose a potential risk for the neurobehavioral system. ispartof: Scientific Reports vol:6 issue:1 ispartof: location:England status: published

Gold nanoparticles functionalized with polyethylene glycol of different chain lengths are used to determine the influence of the capping layer thickness on the radiosensitizing effect of the particles. The size variations in organic coating, built up with polyethylene glycol polymers of molecular weight 1-20 kDa, allow an evaluation of the decrease in dose enhancement percentages caused by the gold nanoparticles at different radial distances from their surface. With localized eradication of malignant cells as a primary focus, radiosensitization is most effective after internalization in the nucleus. For this reason, we performed controlled radiation experiments, with doses up to 20 Gy and particle diameters in a range of 5-30 nm, and studied the relaxation pattern of supercoiled DNA. Subsequent gel electrophoresis of the suspensions was performed to evaluate the molecular damage and consecutively quantify the gold nanoparticle sensitization. In conclusion, on average up to 58.4% of the radiosensitizing efficiency was lost when the radial dimensions of the functionalizing layer were increased from 4.1 to 15.3 nm. These results serve as an experimental supplement for biophysical simulations and demonstrate the influence of an important parameter in the development of nanomaterials for targeted therapies in cancer radiotherapy.

An optical flux sensor, based on the fluorescence properties of materials and nanoparticles, has been developed to control the deposition rate in thin film deposition systems. Using a simple diode laser and a photomultiplier tube with a light filter, we report the detection of gallium atoms and CdSe-ZnS quantum dots. This setup has a high sensitivity and reproducibility. received: 2015-12-24 accepted: 2016-06-30 published: 2016-07-20 ispartof: Review of Scientific Instruments vol:87 issue:7 ispartof: location:United States status: published

In this work, an unusual silicon chemical vapor deposition precursor is used, which allows the safe deposition of thin silica films in a controlled and reproducible manner at a lower thermal budget with a newly developed direct liquid injection − low pressure chemical vapor deposition system. The deposition is controlled by parameters such as deposition temperature, partial pressure of the gases, and flow rate of the precursor solution. X-ray reflectivity and spectroscopic ellipsometry of the deposited samples show that the thickness of the layers is well controlled by deposition temperature, time, and oxygen flow. A growth rate of 4.5 A min−1 is obtained without the addition of oxygen, which can be increased to 10.2 A min−1 by the addition of oxygen. Atomic force microscopy, Rutherford backscattering spectroscopy, Fourier transform infrared spectroscopy, and drop shape analysis are used to measure roughness, composition, and hydrophobicity. Thin films of silicon dioxide are successfully grown. In addition, this newly developed system can be used for a wide range of films by varying the precursors or by co-injecting nanoparticles suspension mixed with the chemical vapor deposition precursor in the direct liquid injection vaporizer.

In this work, the use of a newly developed direct liquid injection low pressure chemical vapor deposition (DLI-LPCVD) system is described, which allows for the deposition of thin films in a controlled and reproducible manner. The capabilities of this system are described via silica thin films deposited using the precursor tetraethyl orthosilicate (TEOS). The deposition of thin films is controlled by parameters, such as deposition temperature, partial pressure of the gases, and flow rate of the precursor solution. The thickness of the deposited layer is varied simply by changing deposition temperature and time. X-ray reflectivity and spectroscopic ellipsometry of the deposited samples show that the thickness of the layers is well controlled by deposition temperature and time. Auger electron spectroscopy, in addition, motivates our choice to use cyclohexane as a solvent. A growth rate of 12.2 A min−1 is obtained. Atomic force microscopy, Rutherford backscattering spectroscopy, Fourier transform infrared spectroscopy, and drop shape analysis are used to measure roughness, composition, and hydrophobicity. Thin films of silicon dioxide are successfully grown by the newly developed DLI-LPCVD system. This system can be used for a wide range of films by varying the precursors.

Nanoparticles of different materials are already in use for many applications. In some applications, these nanoparticles need to be deposited on a substrate in a fast and reproducible way. We have developed a new direct liquid injection system for nanoparticle deposition by chemical vapor deposition using a liquid nanoparticle precursor. The system was designed to deposit nanoparticles in a controlled and reproducible way by using two direct liquid injectors to deliver nanoparticles to the system. The nanoparticle solution is first evaporated and then the nanoparticles flow onto a substrate inside the vacuum chamber. To allow injection and evaporation of the liquid, a direct liquid injection and vaporization system are mounted on top of the process chamber. The deposition of the nanoparticles is controlled by parameters such as deposition temperature, partial pressure of the gases, and flow rate of the nanoparticle suspension. The concentration of the deposited nanoparticles can be varied simply by changing the flow rate and deposition time. We demonstrate the capabilities of this system using gold nanoparticles. The selected suspension flow rates were varied between 0.25 and 1 g/min. AFM analysis of the deposited samples showed that the aggregation of gold nanoparticles is well controlled by the flow and deposition parameters. ispartof: Review of Scientific Instruments vol:87 issue:2 pages:1-7 ispartof: location:NY, New York status: published

In microelectronics build-up technology interfaces are realized between a polymer and a metal. The peel force is a measure for the quality of the adhesion. To improve adhesion between epoxy and electrochemically deposited copper, the polymer is generally pretreated with wet-chemical sweller and oxidizing treatments. It was shown that peel force is strongly dependent on the pretreatment conditions. This paper concerns different sweller and oxidizer treatment times for the epoxy. Copper is deposited by an electroless/electrogalvanic plating process. Before Cu-deposition and after peel force measurements, the obtained surface of the epoxy and the Cu-strips are studied with XPS. Atomic percentages of O, C, N, Cu, Pd and Sn are measured and the spectra are deconvoluted. Based on these results confirmations are presented for the proposed pore development in epoxy polymers due to wet chemical treatments (sweller and oxidizer). Between the XPS-results, peel force and AFM roughness measurements, correlations are presented.