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Organisationseinheit der BAM
The molecular dynamics of linear poly(N-isopropylacrylamide) (pNIPAM) in aqueous media at temperatures below and above the lower critical solution temperature (LCST) are investigated using broadband dielectric relaxation spectroscopy in a frequency range from 10–1 to 1011 Hz. Below the LCST, two relaxation processes are observed in the megahertz and gigahertz region assigned to the reorientation of dipoles of the solvated polymer segments (p-process) and water molecules (w-process), respectively. Both relaxation processes are analyzed using the Havriliak–Negami (HN) function, taking special attention to the w-process. Above the LCST, the dielectric spectra of the pNIPAM solutions resemble that of pure water, showing only the high frequency relaxation process of the water molecules with a more or less Debye-type behavior. The non-Debye behavior of the w-process below the LCST is mainly induced by the interactions between water and pNIPAM chains via hydrogen bonding. The relaxation time and strength of the w-process is studied with dependence on the concentration, temperature, and the polymer chain length (molecular weight). The information obtained is useful for a deeper understanding of the dehydration behavior at the phase transition. The suggestion of dehydration of the pNIPAM chains at the LCST is confirmed by calculating a dehydration number.
Biodetection formats, such as DNA and antibody microarrays, are valuable tools in the life sciences, but for some applications, the detection limits are insufficient. A straightforward strategy to obtain signal amplification is the rolling circle amplification (RCA), an easy, isothermal, and enzymatic nucleic acid synthesis that has already been employed successfully to increase the signal yield for several single-analyte and multiplexing assays in conjunction with hybridization probes. Here, we systematically investigated the parameters responsible for the RCA driven signal amplification with fluorescent labels, such as the type of fluorophore chosen, labeling strategy, composition of reaction solution, and number of handling steps. In labeling strategies, post-synthetic labeling via a Cy3-hybridization probe was compared to the direct incorporation of fluorescent Cy3–dUTP and DY-555–dUTP into the nascent strand during synthesis. With our direct labeling protocol, the assay's runtime and handling steps could be reduced while the signal yield was increased. These features are very attractive for many detection formats but especially for point-of-care diagnostic kits that need to be simple enough to be performed by scientifically untrained personnel.
In this in vitro study, we got a first insight of a possible potential of Hypericin for the treatment of pediatric soft tissue sarcoma. By coupling with radioiodine, we developed a novel approach for a combined anti-tumor treatment. The in vitro experiments lay the foundation for further in vivo experiments, which are needed to study the effects of a sequential administration of 131I-HYP and HYP.