Development of a polystyrene sulfonate/silver nanocomposite with self-healing properties for biomaterial applications

A silver polystyrene sulfonate polyelectrolyte was synthesized, showing a spontaneous reduction of silver ions to silver nanoparticles over a period of approximately 1 month. A follow-up of the nanoparticle formation via scanning electron microscopy (SEM) reveals migration of the nanoparticles towards the cracks of the polymer over time, leading to a self-healing process of the nanocomposite. Antibacterial tests show excellent antibacterial activity of our compound, which allows us to use this compound e.g. for external medical applications.     

LP99: Discovery and Synthesis of the First Selective BRD7/9 Bromodomain Inhibitor

The bromodomain‐containing proteins BRD9 and BRD7 are part of the human SWI/SNF chromatin‐remodeling complexes BAF and PBAF. To date, no selective inhibitor for BRD7/9 has been reported despite its potential value as a biological tool or as a lead for future therapeutics. The quinolone‐fused lactam LP99 is now reported as the first potent and selective inhibitor of the BRD7 and BRD9 bromodomains. Development of LP99 from a fragment hit was expedited through balancing structure‐based inhibitor design and biophysical characterization against tractable chemical synthesis: Complexity‐building nitro‐Mannich/lactamization cascade processes allowed for early structure–activity relationship studies whereas an enantioselective organocatalytic nitro‐Mannich reaction enabled the synthesis of the lead scaffold in enantioenriched form and on scale. This epigenetic probe was shown to inhibit the association of BRD7 and BRD9 to acetylated histones in vitro and in cells. Moreover, LP99 was used to demonstrate that BRD7/9 plays a role in regulating pro‐inflammatory cytokine secretion.     

Simultaneous small‐ and wide‐angle scattering at high X‐ray energies

Combined small‐ and wide‐angle X‐ray scattering (SAXS/WAXS) is a powerful technique for the study of materials at length scales ranging from atomic/molecular sizes (a few angstroms) to the mesoscopic regime (～1 nm to ～1 µm). A set‐up to apply this technique at high X‐ray energies (E > 50 keV) has been developed. Hard X‐rays permit the execution of at least three classes of investigations that are significantly more difficult to perform at standard X‐ray energies (8–20 keV): (i) in situ strain analysis revealing anisotropic strain behaviour both at the atomic (WAXS) as well as at the mesoscopic (SAXS) length scales, (ii) acquisition of WAXS patterns to very large q (>20 Å^?1) thus allowing atomic pair distribution function analysis (SAXS/PDF) of micro‐ and nano‐structured materials, and (iii) utilization of complex sample environments involving thick X‐ray windows and/or samples that can be penetrated only by high‐energy X‐rays. Using the reported set‐up a time resolution of approximately two seconds was demonstrated. It is planned to further improve this time resolution in the near future.     

Investigation of the magnetic properties of ferritin by AFM imaging with magnetic sample modulation

Individual ferritin molecules can be sensitively detected using magnetic sample modulation (MSM) combined with contact mode atomic force microscopy (AFM). To generate an oscillating magnetic field, an alternating current (AC) was applied to a solenoid placed within the base of the AFM sample stage. When a modulated electromagnetic field is applied to samples, ferromagnetic and paramagnetic nanomaterials are induced to vibrate. The flux of the AC electromagnetic field causes the ferritin samples to vibrate with corresponding rhythm and periodicity of the applied field. This motion can be detected and mapped using contact mode AFM with a soft, nonmagnetic cantilever. Changes in the phase and amplitude of the periodic motion of the sample are sensed by the tip to selectively map vibrating magnetic nanomaterials. Particle lithography was used to create nanopatterned test platforms of ferritin for MSM measurements. Regularly spaced structures of proteins provide precise reproducible dimensions for multiple successive surface measurements at dimensions of tens of nanometers. Figure Ring patterns of ferritin were used as nanoscale test platforms to characterize magnetic properties at the level of individual proteins with AFM imaging

A validated method for the determination of traces of UV filters in fish using LC–MS/MS

An analytical method for the determination of UV filter substances in fish tissue has been developed and validated using benzophenone-3, 3-(4-methylbenzylidene)-camphor, 2-ethylhexyl-2-cyano-3,3-diphenyl-2-propenoate and 2-ethylhexyl 3-(methoxyphenyl)-2-propenoate as target analytes. The fish fillets were homogenised and extracted by Soxhlet extraction. The extracts were run through a clean-up process including gel permeation chromatography followed by solid-phase extraction. Quantification of the compounds was performed using liquid chromatography with tandem mass spectrometric detection. Blank fish as well as spiked blank fish were analysed to validate the analytical method. The analytical method developed has the multiple advantages of enabling separation, simultaneous identification and quantification of each of the four selected compounds in a single run. Contamination of blank samples and abnormally high concentrations in spiked samples were avoided by taking extensive precautions during the fish preparation procedure. The method was validated in accordance with internationally accepted criteria, such as specificity, accuracy and repeatability. The combination of LC with tandem mass spectrometry ensures a high level of specificity. The accuracy of the method was reported as the mean recovery rate for the analytes in the sample matrix. Mean recoveries were in the range 86–108%. The precision is expressed as the relative standard deviation, and in all but one of the cases was 20% or below. The accuracy of the method allows residue analyses to be performed on biological matrices at ng/g levels. The determined limit of quantification for each analyte was 8 ng/g fish. For all spiking levels ≥8 ng/g, relative standard deviations were ≤ 20%.