Daniel Sickert

Validating Alzheimer's disease micro RNAs using next-generation sequencing.

Molecular biomarkers for Alzheimers disease (AD) can support detection and improved care for patients, but novel candidates require verification. We previously reported a 12‐micro RNA (miRNA) blood‐based signature using next‐generation sequencing (NGS) of 54 AD cases and 22 controls.

Influence of Next-Generation Sequencing and Storage Conditions on miRNA Patterns Generated from PAXgene Blood

Whole blood derived miRNA signatures determined by Next-Generation Sequencing (NGS) offer themselves as future minimally invasive biomarkers for various human diseases. The PAXgene system is a commonly used blood storage system for miRNA analysis. Central to all miRNA analyses that aim to identify disease specific miRNA signatures, is the question of stability and variability of the miRNA profiles that are generated by NGS. We characterized the influence of five different conditions on the genome wide miRNA expression pattern of human blood isolated in PAXgene RNA tubes. In detail, we analyzed 15 miRNomes from three individuals. The blood was subjected to different numbers of freeze/thaw cycles and analyzed for the influence of storage at -80 or 8 °C. We also determined the influence of blood collection and NGS preparations on the miRNA pattern isolated from a single individual, which has been sequenced 10 times. Here, five PAXGene tubes were consecutively collected that have been split in two replicates, representing two experimental batches. All samples were analyzed by Illumina NGS. For each sample, approximately 20 million NGS reads have been generated. Hierarchical clustering and Principal Component Analysis (PCA) showed an influence of the different conditions on the miRNA patterns. The effects of the different conditions on miRNA abundance are, however, smaller than the differences that are due to interindividual variability. We also found evidence for an influence of the NGS measurement on the miRNA pattern. Specifically, hsa-miR-1271-5p and hsa-miR-182-5p showed coefficients of variation above 100% indicating a strong influence of the NGS protocol on the abundance of these miRNAs.

Separation and Assembly of DNA‐dispersed Carbon Nanotubes by Dielectrophoresis

Current production methods for single wall carbon nanotubes (SWCNT) yield a mixture of metallic and semiconducting SWCNT, mostly bundled. Recent publications suggested the separation of metallic and semiconducting species by dielectrophoresis (DEP). We demonstrate the enrichment of metallic SWCNT in self‐assembled wires deposited dielectrophoretically from a DNA dispersed suspension by applying resonant Raman spectroscopy. Our modification of the DEP separation process provides compatibility to bionanotechnology assembly approaches by avoiding tensides.

Frequency Response of Thin-Film Bulk Acoustic Resonators to the Deposition of Tungsten, Platinum, Aluminium Oxide and Carbon Nanotube Thin-Films

Thin-film bulk acoustic resonators (FBAR) can be used as mass sensors when the adsorbed mass is linear to the frequency shift caused by the adsorption. This is, however, only the case if the adsorbed layer is thin compared to the thickness of the resonator. In this paper, we investigate the adsorption of films with thicknesses of some nanometres up to few hundreds of nanometres. With this range, we cover films thicknesses being small compared to the resonator and thicknesses in the range of the resonator thickness. The adsorption of materials was simulated for materials with different mass densities and acoustic velocities. Thin films of platinum, aluminium oxide, tungsten and carbon nanotubes were deposited on the FBAR and the results were fitted to the model used in the simulations. The acoustic velocity of the carbon nanotube films was much lower than the other materials investigated in this study. With this interesting property, carbon nanotube thin-films are a promising material for acoustic devices where materials with particularly low acoustic impedance are desired. The paper shows that the FBAR can be a useful tool to characterise mechanical properties of thin films in situ in the micro- and nanoscale within a certain range of parameters.