OMNY PIN-A versatile sample holder for tomographic measurements at room and cryogenic temperatures

Nowadays ptychographic tomography in the hard x-ray regime, i.e., at energies above about 2 keV, is a well-established measurement technique. At the Paul Scherrer Institut, currently two instruments are available: one is measuring at room temperature and atmospheric pressure, and the other, the socalled OMNY (tOMography Nano crYo) instrument, is operating at ultra-high vacuum and offering cryogenic sample temperatures down to 10 K. In this manuscript, we present the sample mounts that were developed for these instruments. Aside from excellent mechanical stability and thermal conductivity, they also offer highly reproducible mounting. Various types were developed for different kinds of samples and are presented in detail, including examples of how specimens can be mounted on these holders. We also show the first hard x-ray ptychographic tomography measurements of high-pressure frozen biological samples, in the present case Chlamydomonas cells, the related sample pins and preparation steps. For completeness, we present accessories such as transportation containers for both room temperature and cryogenic samples and a gripper mechanism for automatic sample changing. The sample mounts are not limited to x-ray tomography or hard x-ray energies, and we believe that they can be very useful for other instrumentation projects. (C) 2017 Author(s)

OMNY-A tOMography Nano crYo stage

For many scientific questions gaining three-dimensional insight into a specimen can provide valuable information. We here present an instrument called "tOMography Nano crYo (OMNY)," dedicated to high resolution 3D scanning x-ray microscopy at cryogenic conditions via hard X-ray ptychography. Ptychography is a lens-less imaging method requiring accurate sample positioning. In OMNY, this in achieved via dedicated laser interferometry and closed-loop position control reaching sub-10 nm positioning accuracy. Cryogenic sample conditions are maintained via conductive cooling. 90 K can be reached when using liquid nitrogen as coolant, and 10 K is possible with liquid helium. A cryogenic sample-change mechanism permits measurements of cryogenically fixed specimens. We compare images obtained with OMNY with older measurements performed using a nitrogen gas cryo-jet of stained, epoxy-embedded retina tissue and of frozen-hydrated Chlamydomonas cells. (C) 2018 Author(s)

Live-fibroblast IR imaging of a cytoprotective PhotoCORM Activated with Visible Light

Carbon monoxide releasing molecules (CORMs) are an emerging class of pharmaceutical compounds currently evaluated in several preclinical disease models. There is general consensus that the therapeutic effects elicited by the molecules may be directly ascribed to the biological function of the released CO. It remains unclear, however, if cellular internalization of CORMs is a critical event in their therapeutic action. To address the problem of cellular delivery, we have devised a general strategy which entails conjugation of a CO-releasing molecule (here a photoactivated CORM) to the 5'-OH ribose group of vitamin B12. Cyanocobalamin (B12) functions as the biocompatible water-soluble scaffold which actively transports the CORM against a concentration gradient into the cells. The uptake and cellular distribution of this B12-photoCORM conjugate is demonstrated via synchrotron FTIR spectromicroscopy measurements on living cells. Intracellular photoinduced CO release prevents fibroblasts from dying under conditions of hypoxia and metabolic depletion, conditions that may occur in vivo during insufficient blood supply to oxygen-sensitive tissues such as the heart or brain