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Analysis of single cells via LA-ICP-MS is a technique with great potential, however manual targeting of single cells is laborious and therefore microarraying of cells looks promising. In this work, we investigate the potential of a commercial non-contact piezo dispenser arraying system (S3, Scienion AG, Berlin), equipped with a novel technology for single-cell isolation called CellenONE™ (Cellenion, Lyon). Usually if one aims to create a microarray of single cells via spotting a suitably diluted cell suspension, one will observe a Poisson-distributed cell number per spot. CellenONE™ overcomes this problem by controlling the number of cells optically in the piezo dispense capillary (PDC) via image recognition to obtain true single cell arrays. The figures of merit of the customized and optimized setup will be presented. In a proof of concept experiment we investigated the trace elemental fingerprint of THP-1 cells by LA-ICP-TOF-MS (Analyte G2, Teledyne Cetac; icpTOF, TOFWERK) and quantified two metal cell dyes, mDOTA-Ho (CheMatech, Dijon), and Ir-DNA intercalator (Fluidigm, San Francisco). For that, matrix matched calibration standards after Wang et al. were successfully prepared using the same arraying system. We believe that this novel approach opens new ways for automated quantitative single cell LA-ICP-MS.
The rapid mass calorimeter based on reduced‐size specimens is proposed for accelerated fire
testing and put up for discussion, particularly for flame retarded polymeric materials. A mass loss
calorimeter is combined with a semiautomatic sample changer. Experiments on specimens of
reduced size were conducted on poly(methyl methacrylate), poly(propylene), polyamide 66,
poly(ether ether ketone), and pine sapwood square samples with edge lengths of 100, 75, 50,
25, 20, and 10 mm. Specimens of 20 × 20 mm2 were selected to achieve a crucial reduction in
specimen size and a measuring protocol developed. A total of 71 different polymeric materials
were investigated in the rapid mass calorimeter and cone calorimeter for comparison and several
materials with different heat release rate characteristics in the pyrolysis combustion flow calorimeter to test this additional screening method as well. The important fire properties obtained in the rapid mass calorimeter show reasonable correlation with the cone calorimeter results but also with the oxygen index. All in all, the rapid mass calorimeter produces reliable and meaningful results and, despite acceleration and size reduction, still allows for a certain degree of burning behavior interpretation. Material savings of 96% and time savings of around 60%‐70% are achieved compared to measure cone calorimeter.
The effects of reducing specimen size on the fire behavior of polymeric materials were investigated by means of the rapid mass calorimeter, a high-throughput Screening instrument. Results from the rapid mass calorimeter were compared with those from the cone calorimeter. Correlation coefficients between the different measures of each method and between the two methods are discussed to elucidate the differences and similarities in the two methods. Materials with characteristic heat release rate (HRR) curves in the cone calorimeter were evaluated in detail. The rapid mass calorimeter produces valuable and interpretable results with HRR curve characteristics similar to cone calorimeter results. Compared to cone calorimeter measurements, material savings of 96% are achieved, while maintaining the Advantages of a macroscopic fire test.
Microorganisms accumulate molar concentrations of compatible solutes like ectoine to prevent proteins from denaturation. Direct structural or spectroscopic information on the mechanism and about the hydration shell around ectoine are scarce. We combined surface plasmon resonance (SPR), confocal Raman spectroscopy, molecular dynamics simulations, and density functional theory (DFT) calculations to study the local hydration shell around ectoine and its influence on the binding of a gene-S-protein (G5P) to a single-stranded DNA (dT(25)). Due to the very high hygroscopicity of ectoine, it was possible to analyze the highly stable hydration shell by confocal Raman spectroscopy. Corresponding molecular dynamics simulation results revealed a significant change of the water dielectric constant in the presence of a high molar ectoine concentration as compared to pure water. The SPR data showed that the amount of protein bound to DNA decreases in the presence of ectoine, and hence, the protein-DNA dissociation constant increases in a concentration-dependent manner. Concomitantly, the Raman spectra in terms of the amide I region revealed large changes in the protein secondary structure. Our results indicate that ectoine strongly affects the molecular recognition between the protein and the oligonudeotide, which has important consequences for osmotic regulation mechanisms.