Scientific publications

In this study, two different synthetic methods in aqueous solution are presented to tune the optical properties of CdTe and CdSe semiconductor nanoparticles. Additionally, the influence of different temperatures, pressures, precursor ratios, surface ligands, bases, and core components in the synthesis was investigated with regard to the particle sizes and optical properties. As a result, a red shift of the emission and absorption maxima with increasing reaction temperature (100 to 220°C), pressure (1 to 25 bar), and different ratios of core components of alloyed semiconductor nanoparticles could be observed without a change of the particle size. An increase in particle size from 2.5 to 5 nm was only achieved by variation of the mercaptocarboxylic acid ligands in combination with the reaction time and used base. To get a first hint on the cytotoxic effects and cell uptake of the synthesized quantum dots, in vitro tests mesenchymal stem cells (MSCs) were carried out.

Controlled fragrance release at the right time, in the right place, depending on the context remains a technological challenge in the areas of psychophysiology, biochemistry and the entertainment industry. In this study, we demonstrate how bulk poly(dimethylsiloxane) (PDMS) templates may effectively take up and retain volatile organic compounds of essential orange oil in the original form without significantly shifting the scent profile. This is done depending on the sampling approach that follows a controllable and slow fragrance release maintaining a constant ratio of volatile compounds in a template-thickness, temperature and time-dependent manner. Thus, the increase in temperature up to 80 [degree]C enhances the intensity of the fragrance release almost 13 fold without a significant shift in the chemical profile for 6 consecutive "ON/OFF" cycles. We believe that the concept demonstrated here towards fragrance storage via bulk PDMS templates can be used as a model case for the future use of scents.

This work introduces for the first time titanium disulfide (TiS2)/carbon nanotube (CNT) electrodes for desalination of high molarity saline water. Capitalizing on the two-dimensional layered structure of TiS2, cations can be effectively removed from a feedwater stream by intercalation. The TiS2–CNT hybrid electrode is paired in an asymmetric cell with microporous activated carbon cloth without an ion exchange membrane. By electrochemical analysis, the correlation between the state of charge and the stability of TiS2 was investigated. By using post-mortem X-ray diffraction, the sodium-ion intercalation mechanism gives an insight into how the state of charge affects the structure and cyclic stability. Our system showed stable desalination performance over 70 cycles at high molar concentration (600 mM), with a cell salt removal capacity of 14 mg/g (equivalent to a sodium removal capacity of 35.8 mg/g normalized to the mass of TiS2–CNT). This novel approach of membrane-free hybrid Faradaic capacitive deionization paves the way toward energy-efficient desalination of seawater.

In recent years, there has been increasing interest in studying listening effort. Research on listening effort intersects with the development of active theories of speech perception and contributes to the broader endeavor of understanding speech perception within the context of neuroscientific theories of perception, attention, and effort. Due to the multidisciplinary nature of the problem, researchers vary widely in their precise conceptualization of the catch-all term listening effort. Very recent consensus work stresses the relationship between listening effort and the allocation of cognitive resources, providing a conceptual link to current cognitive neuropsychological theories associating effort with the allocation of selective attention. By linking listening effort to attentional effort, we enable the application of a taxonomy of external and internal attention to the characterization of effortful listening. More specifically, we use a vectorial model to decompose the demand causing listening effort into its mutually orthogonal external and internal components and map the relationship between demanded and exerted effort by means of a resource-limiting term that can represent the influence of motivation as well as vigilance and arousal. Due to its quantitative nature and easy graphical interpretation, this model can be applied to a broad range of problems dealing with listening effort. As such, we conclude that the model provides a good starting point for further research on effortful listening within a more differentiated neuropsychological framework.

3D bioprinting is a booming method to obtain scaffolds of different materials with predesigned and customized morphologies and geometries. In this review we focus on the experimental strategies and recent achievements in the bioprinting of major structural proteins (collagen, silk, fibrin), as a particularly interesting technology to reconstruct the biochemical and biophysical composition and hierarchical morphology of natural scaffolds. The flexibility in molecular design offered by structural proteins, combined with the flexibility in mixing, deposition, and mechanical processing inherent to bioprinting technologies, enables the fabrication of highly functional scaffolds and tissue mimics with a degree of complexity and organization which has only just started to be explored. Here we describe the printing parameters and physical (mechanical) properties of bioinks based on structural proteins, including the biological function of the printed scaffolds. We describe applied printing techniques and cross-linking methods, highlighting the modifications implemented to improve scaffold properties. The used cell types, cell viability, and possible construct applications are also reported. We envision that the application of printing technologies to structural proteins will enable unprecedented control over their supramolecular organization, conferring printed scaffolds biological properties and functions close to natural systems.

This work reports an in vivo approach for identifying the function of biomineralization-related proteins. Synthetic sequences of n16N, OC-17 and perlucin with signal peptides are produced in a novel Gateway expression system for Dictyostelium under the control of the [ecmB] promoter. A fast and easy scanning electron microscopic screening method was used to differentiate on the colony level between interplay effects of the proteins expressed in the extracellular matrix (ECM). Transformed Dictyostelium, which migrated as multicellular colonies on calcite crystals and left their ECM remnants on the surface were investigated by scanning electron microscopy. Calcium minerals with and without phosphorous accumulated very frequently within the matrix of the Dictyostelium colonies when grown on calcite. Magnesium containing phosphorous granules were observed when colonies were exposed on silica. The absence of calcium EDX signals in these cases suggests that the external calcite crystals but not living cells represent the major source of calcium in the ECM. Several features of the system provide first evidence that each protein influences the properties of the matrix in a characteristic mode. Colonies transformed with perlucin produced a matrix with cracks on the length scale of a few microns throughout the matrix patch. For colonies with OC-17, almost no cracks were observed, regardless of the length scale. The non-transformed Dictyostelium (Ax3-Orf+) produced larger cracks. The strategy presented here develops the first step towards an efficient eukaryotic screening system for the combinatorial functionalization of materials by bioengineering in close analogy to natural biomineralization concepts.

This paper reports a rapid HILIC-ESI–MS assay to quantify dipalmitoylphosphatidylcholine (DPPC) as component of lung surfactant for nanosafety studies. The technique was used to investigate the concentration-dependent sorption of DPPC to two-sizes of amorphous SiO2 nanoparticles (SiO2-NPs) in a MeOH:H2O (50/50 v/v) mixture and in cell culture medium. In MeOH:H2O (50/50 v/v), the sorption of DPPC was positively correlated with the nanoparticles concentration. A substantial affinity of small amorphous SiO2-NPs (25 nm) to DPPC standard solution compared to bigger SiO2-NPs (75 nm) was not confirmed for biological specimens. After dispersion of SiO2-NPs in DPPC containing cell culture medium, the capacity of the SiO2-NPs to bind DPPC was reduced in comparison to a mixture of MeOH:H2O (50/50 v/v) regardless from the nanoparticles size. Furthermore, HILIC-ESI–MS revealed that A549 cells internalized DPPC during growth in serum containing medium complemented with DPPC. This finding was in a good agreement with the potential of alveolar type II cells to recycle surfactant components. Binding of lipids present in the cell culture medium to amorphous SiO2-NPs was supported by means of HILIC-ESI–MS, TEM and ICP-MS independently.

In this study, we report p-coumaric acid as novel and effective response marker for indirectly measuring the levels of hypoxia in normal primary bronchial epithelial cells. We developed a simple and rapid technique based on hydrophilic interaction chromatography-electrospray ionization-mass spectrometry (HILIC-ESI–MS). During 168 h of hypoxia without induction of reactive oxygen species (ROS), an almost linear increase of p-coumaric acid levels was observed. We interpret the increasing p-coumaric acid concentrations during hypoxia as a result of cell damage, triggered by reduced co-enzyme Q10 levels, because the oxidative cascade was not able to supply sufficient energy. The HILIC-ESI–MS assay within p-coumaric acid exhibited a linear dynamic range from 60 to 610 ng/μL with correlation coefficient of 0.9998. The precision of the assay was ≤15% RSD and method accuracies between 97 and 108%.

In this study, a simple, rapid and inexpensive approach for the screening of heavy metals with photometric reagents was developed based on porous, anodic aluminium oxide (AAO) films, with detection limits of 0.45 mg L-1 (Co2+), 0.25 mg L-1 (Pb2+) and 0.59 mg L-1 (Ni2+). Noble metal ions Ag+ and Pd2+, as well as Cu2+, formed nanoparticles within the AAO channels during micro-solid phase extraction driven by galvanic electroless displacement followed by UV detection.

We report a simple fast, practical and effective method for the replication of the complex venation patterns of natural leaves into PDMS with accuracy down to a lateral size of 500 nm. Optimising the amount of crosslinker enabled the replication and sealing of the microvascular structures to yield enclosed microfluidic networks. The use of plant leaves as templates for soft lithography was demonstrated across over ten species and included reticulate, arcuate, pinnate, parallel and palmate venation patterns. SEM imaging revealed replication of the plants microscopic and sub-microscopic topography into the PDMS structures, making this method especially attractive for mimicking biological structures for in vitro assays. Flow analysis revealed that the autonomous liquid transport velocity in 1st-order microchannel was 1.5-2.2 times faster than that in the 2nd-order microchannels across three leaf types, with the sorptivity rule surprisingly preserved during self-powered flow through leaf-inspired vascularity from Carpinus betulus.