A Correlative Analysis of Gold Nanoparticles Internalized by A549 Cells

Fluorescently labeled nanoparticles are widely used to investigate nanoparticle cell interactions by fluorescence microscopy. Owing to limited lateral and axial resolution, nanostructures (<100 nm) cannot be resolved by conventional light micro­scopy techniques. Especially after uptake into cells, a common fate of the fluorescence label and the particle core cannot be taken for granted. In this study, a correlative approach is presented to image fluorescently labeled gold nanoparticles inside whole cells by correlative light and electron microscopy (CLEM). This approach allows for detection of the fluorescently labeled particle shell as well as for the gold core in one sample. In this setup, A549 cells are exposed to 8 nm Atto 647N‐labeled gold nanoparticles (3.3 × 10⁹ particles mL^?1, 0.02 μg Au mL^?1) for 5 h and are subsequently imaged by confocal laser scanning microscopy (CLSM) and transmission electron microscopy (TEM). Eight fluorescence signals located at different intracellular positions are further analyzed by TEM. Five of the eight fluorescence spots are correlated with isolated or agglomerated gold nanoparticles. Three fluorescence signals could not be related to the presence of gold, indicating a loss of the particle shell.     

Water‐Based Adhesives with Tailored Hydrophobic Association: Dilution Resistance and Improved Setting Behavior

Hydrophobic association and stimuli‐responsiveness is a powerful tool towards water‐based adhesives with strongly improved properties, which is demonstrated based on the example of hydrophobically modified alkali‐soluble latexes (HASE) with modulated association. Their rheological properties are highly tunable due to the hydrophobic domains that act as physical crosslinking sites of adjustable interaction strength. Ethanol, propanol, and butanol are used as water‐soluble model additives with different hydrophobicity in order to specifically target the association sites and impact the viscoelastic properties and stimuli‐responsiveness. The rheological and mechanical property response upon dilution with water can be tailored, and dilution‐resistant or even dilution‐thickening systems are obtained. The investigations are of high importance for water‐based adhesives, as our findings provide insight into general structure–property relationships to improve their setting behavior, especially upon contact with wet substrates.

     

Novel one-pot process for the synthesis of 1,3-thiazoles via organocatalysed epoxidation of nitro-olefins

A facile one-pot two-step process for the synthesis of 1,3-thiazole heterocycles via organocatalytic epoxidation of nitro-olefins with the t-BuOOH/DBU system, and subsequent reaction of α-nitro-epoxides with thioamides under mild conditions has been developed.     

Presence of galactosylated core fucose on N-glycans in the planaria Dugesia japonica

Planarial species are of especial interest to biologists due to the phenomenon of pluripotency and, in comparison to other developmental processes, it can be hypothesised that glycan-lectin interactions may play a role. In order to examine the N-glycans of one of these organisms, Dugesia japonica, peptide:N-glycosidase A was employed and the released glycans were subject to pyridylamination, HPLC and mass spectrometric analysis. A range of oligomannosidic glycans was observed with a trimethylated Man(5) GlcNAc(2) structure being the dominant species. Three glycans were also observed to contain deoxyhexose; in particular, a glycan with the composition Hex(4) HexNAc(2) Fuc(1) Me(2) was revealed by exoglycosidase digestion, in combination with MS/MS, to contain a galactosylated core α1,6-fucose residue, whereas this core modification was found to be capped with a methylhexose residue in the case of a Hex(5) HexNAc(2) Fuc(1) Me(3) structure. This is the first report of these types of structures in a platyhelminth and indicates that the 'GalFuc' modification of N-glycans is not just restricted to molluscs and nematodes.     

Modelling and Simulation of Food Foams

The rheological behaviour of protein solutions containing bubbles at rest, but particularly during fluid mechanical transport is not sufficiently investigated yet. Protein foams have a great importance in food production because of their special sensory properties. A suspension that contains bubbles in a Newtonian liquid exhibits inherently a complex rheological behaviour, such as elastic effects, a shear- and time-dependent viscosity and normal stress differences. The deformation state of the bubbles in a suspension subjected to a steady shear is a function of the gas volume fraction ϕ and the capillary number N_Ca. In the present article, material equations for protein solutions with gas volume fractions ϕ ≤ 0.75 and small bubble deformations, i. e. N_Ca ≪ 1, are analysed and further developed. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

On the Stability of Liquid Nanodroplets in Polymerizable Miniemulsions

Liquid nanodroplets within a size range of 50 to 500 nm can easily be prepared by shearing a system containing oil, water and a surfactant. The growth of the nanodroplets can effectively be suppressed by using a strong hydrophobe as an additivie to the oil and an effective surfactant. The hydrophobe acts as an osmotic agent which stabilizes the system against Ostwald ripening. The growth of the droplets by collision is controlled by the density of the surfactant layer. Freshly prepared miniemulsions are “critically stabilized” and show a slow, but pronounced growth, whereas a miniemulsion in “equilibrium” exhibits constant droplet size on longer time scales. Polymerization of the oil droplets of such miniemulsions turns out to be very promising and extends the possibilities of classical emulsion polymerization. Since each droplet can be considered a small reactor in which polymerization reactions take place, the process allows one to create new particle structures, e.g. polyaddition reactions can take advantage of unusual monomers, the incorporation of materials which are not soluble in the continuous phase, and the formation of nanocapsules.     

Degradation products of proguanil — 4-chloroaniline and related components with regard to genotoxicity

In the event of genotoxic impurities in drug products, knowledge of the origin and fate of these components is of particular importance. In the present study, commercially available proguanil tablets (Paludrine®) were investigated in respect of formation of the main degradation product, 4-chloroaniline (PCA), which is known to be genotoxic. The investigations made use of high performance liquid chromatography coupled with fluorescence detection (HPLC-FLD) and gas chromatography coupled with flame ionisation detection (GC-FID) systems. In addition, proposals for the structure of further proguanil degradation products were developed based on results obtained by mass spectroscopy (HPLC-MS). Database analysis using DEREK, MCASE, and Vitic was performed to obtain an initial toxicological evaluation of the proposed chemical structures. Finally, the absence of the newly established structures in stored proguanil tablets was verified.     

Artificial Multi‐Enzyme Networks for the Asymmetric Amination of sec‐Alcohols

Various artificial network designs that involve biocatalysts were tested for the asymmetric amination of sec‐alcohols to the corresponding α‐chiral primary amines. The artificial systems tested involved three to five redox enzymes and were exemplary of a range of different sec‐alcohol substrates. Alcohols were oxidised to the corresponding ketone by an alcohol dehydrogenase. The ketones were subsequently aminated by employing a ω‐transaminase. Of special interest were redox‐neutral designs in which the hydride abstracted in the oxidation step was reused in the amination step of the cascade. Under optimised conditions up to 91 % conversion of an alcohol to the amine was achieved.     

Raman Spectroscopic Imaging for the Real‐Time Detection of Chemical Changes Associated with Docetaxel Exposure

There is an urgent need for methods allowing for a fast, non‐invasive, sensitive and selective monitoring of the effectiveness of anticancer drugs during the course of a chemotherapeutic treatment of cancer patients. The possibility of predicting and controlling the efficiency of chemotherapeutic agents for every patient individually enables a personalized therapy with largely improved success rates. The results presented herein demonstrate that Raman microspectroscopy is perfectly suited to monitor the impact of chemotherapeutic agents on living cells. The influence of the clinically well‐established chemotherapeutic docetaxel on both the morphology and also biochemistry of living colon cancer cells (HT‐29) has been studied by means of Raman spectroscopy in combination with modern chemometric approaches. The work presented paves the way for establishing Raman spectroscopy as a monitoring tool of the effectiveness of a chemotherapy treatment and can therefore be seen as a step towards personalized therapy.