Integrating advanced functionality in a microfabricated high-throughput fluorescent-activated cell sorter

The integration of complete analyses systems "on chip" is one of the great potentials of microfabricated devices. In this study we present a new pressure-driven microfabricated fluorescent-activated cell sorter chip with advanced functional integration. Using this sorter, fluorescent latex beads are sorted from chicken red blood cells, achieving substantial enrichments at a sample throughput of 12000 cells s(-1). As a part of the sorter chip, we have developed a monolithically integrated single step coaxial flow compound for hydrodynamic focusing of samples in flow cytometry and cell sorting. The structure is simple, and can easily be microfabricated and integrated with other microfluidic components. We have designed an integrated chamber on the chip for holding and culturing of the sorted cells. By integrating this chamber, the risk of losing cells during cell handling processes is eliminated. Furthermore, we have also developed integrated optics for cell detection. Our new design contributes to the ongoing efforts for building a fully integrated micro cell sorting and analysing system.     

Low Molecular Weight Norbornadiene Derivatives for Molecular Solar‐Thermal Energy Storage

Molecular solar‐thermal energy storage systems are based on molecular switches that reversibly convert solar energy into chemical energy. Herein, we report the synthesis, characterization, and computational evaluation of a series of low molecular weight (193–260 g mol^?1) norbornadiene–quadricyclane systems. The molecules feature cyano acceptor and ethynyl‐substituted aromatic donor groups, leading to a good match with solar irradiation, quantitative photo‐thermal conversion between the norbornadiene and quadricyclane, as well as high energy storage densities (396–629 kJ kg^?1). The spectroscopic properties and energy storage capability have been further evaluated through density functional theory calculations, which indicate that the ethynyl moiety plays a critical role in obtaining the high oscillator strengths seen for these molecules.     

Phase separation and crystallinity in proton conducting membranes of styrene grafted and sulfonated poly(vinylidene fluoride)

A series of proton exchange membranes have been prepared by the preirradiation grafting method. Styrene was grafted onto a matrix of poly(vinylidene fluoride) (PVDF) after electron beam irradiation. Part of the samples was crosslinked with divinylbenzene (DVB) or bis(vinylphenyl)ethane (BVPE). Subsequent sulfonation gave membranes grafted with poly(styrene sulfonic acid) and marked PVDF‐g‐PSSA. It was found that the intrinsic crystallinity of the matrix decreased in both the grafting and the sulfonation reaction in all the membranes. The graft penetration and the ion conductivity are influenced strongly by the crosslinker. The ion conductivity is considerably lower in crosslinked membranes than in noncrosslinked ones. Generally, the mechanical strength decreases with crosslinking. The membranes show a regular phase separated structure in which the sulfonated grafts are incorporated in the amorphous parts of the matrix polymer. The phase separated domains are small, of the order of magnitude of 100–250 nm. These were resolved on transmission electron micrographs and on atomic force images but could not be resolved with microprobe Raman spectroscopy. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1741–1753, 1999     

A Double-Edged Sword: Thioxanthenes Act on Both the Mind and the Microbiome

The rising tide of antibacterial drug resistance has given rise to the virtual elimination of numerous erstwhile antibiotics, intensifying the urgent demand for novel agents. A number of drugs have been found to possess potent antimicrobial action during the past several years and have the potential to supplement or even replace the antibiotics. Many of these ‘non-antibiotics’, as they are referred to, belong to the widely used class of neuroleptics, the phenothiazines. Another chemically and pharmacologically related class is the thioxanthenes, differing in that the aromatic N of the central phenothiazine ring has been replaced by a C atom. Such “carbon-analogues” were primarily synthesized with the hope that these would be devoid of some of the toxic effects of phenothiazines. Intensive studies on syntheses, as well as chemical and pharmacological properties of thioxanthenes, were initiated in the late 1950s. Although a rather close parallelism with respect to structure activity relationships could be observed between phenothiazines and thioxanthenes; several thioxanthenes were synthesized in pharmaceutical industries and applied for human use as neuroleptics. Antibacterial activities of thioxanthenes came to be recognized in the early 1980s in Europe. During the following years, many of these drugs were found not only to be antibacterial agents but also to possess anti-mycobacterial, antiviral (including anti-HIV and anti-SARS-CoV-2) and anti-parasitic properties. Thus, this group of drugs, which has an inhibitory effect on the growth of a wide variety of microorganisms, needs to be explored for syntheses of novel antimicrobial agents. The purpose of this review is to summarize the neuroleptic and antimicrobial properties of this exciting group of bioactive molecules with a goal of identifying potential structures worthy of future exploration.     

Influence of Heterogeneity on the Ultrafast Photoisomerization Dynamics of Pfr in Cph1 Phytochrome

Photoisomerization of a protein‐bound chromophore is the basis of light sensing and signaling in many photoreceptors. Phytochrome photoreceptors can be photoconverted reversibly between the Pr and Pfr states through photoisomerization of the methine bridge between rings C and D. Ground‐state heterogeneity of the chromophore has been reported for both Pr and Pfr. Here, we report ultrafast visible (Vis) pump–probe and femtosecond polarization‐resolved Vis pump–infrared (IR) probe studies of the Pfr photoreaction in native and ¹³C/¹⁵N‐labeled Cph1 phytochrome with unlabeled PCB chromophore, demonstrating different S₀ substates, Pfr‐I and Pfr‐II, with distinct IR absorptions, orientations and dynamics of the carbonyl vibration of ring D. We derived time constants of 0.24 ps, 0.7 ps and 6 ps, describing the complete initial photoreaction. We identified an isomerizing pathway with 0.7 ps for Pfr‐I, and silent dynamics with 6 ps for Pfr‐II. We discuss different origins of the Pfr substates, and favor different facial orientations of ring D. The model provides a quantum yield for Pfr‐I of 38%, in line with ~35% ring D rotation in the electronic excited state. We tentatively assign the silent form Pfr‐II to a dark‐adapted state that can convert to Pfr‐I upon light absorption.     

Stable isotope labels as a tool to determine the iron absorption by Peruvian school children from a breakfast meal

Fractional iron absorption from a breakfast meal was determined in Peruvian children employing stable iron isotopes as labels. Iron isotopic analysis was performed by the recently developed negative thermal ionization technique for high-precision iron isotope ratio measurements using FeF₄ ^– ions. By increasing the ascorbic acid content of the standard breakfast meal as served within the Peruvian school-breakfast program from 27 mg to 70 mg, it was possible to increase the geometric mean fractional iron absorption significantly from 5.1% (range 1.6–13.5%) to 8.2% (range 3.1–25.8%). Fractional iron absorption was calculated according to isotope dilution principles and by considering the non-monoisotopic character of the used spikes.     

The Glitazone Class of Drugs as Carbonic Anhydrase Inhibitors—A Spin-Off Discovery from Fragment Screening

The approved drugs that target carbonic anhydrases (CA, EC 4.2.1.1), a family of zinc metalloenzymes, comprise almost exclusively of primary sulfonamides (R-SO₂NH₂) as the zinc binding chemotype. New clinical applications for CA inhibitors, particularly for hard-to-treat cancers, has driven a growing interest in the development of novel CA inhibitors. We recently discovered that the thiazolidinedione heterocycle, where the ring nitrogen carries no substituent, is a new zinc binding group and an alternate CA inhibitor chemotype. This heterocycle is curiously also a substructure of the glitazone class of drugs used in the treatment options for type 2 diabetes. Herein, we investigate and characterise three glitazone drugs (troglitazone 11, rosiglitazone 12 and pioglitazone 13) for binding to CA using native mass spectrometry, protein X-ray crystallography and hydrogen–deuterium exchange (HDX) mass spectrometry, followed by CA enzyme inhibition studies. The glitazone drugs all displayed appreciable binding to and inhibition of CA isozymes. Given that thiazolidinediones are not credited as a zinc binding group nor known as CA inhibitors, our findings indicate that CA may be an off-target of these compounds when used clinically. Furthermore, thiazolidinediones may represent a new opportunity for the development of novel CA inhibitors as future drugs.     

Prodigiosin Sensitizes Sensitive and Resistant Urothelial Carcinoma Cells to Cisplatin Treatment

Cisplatin-based treatment is the standard of care therapy for urothelial carcinomas. However, complex cisplatin resistance mechanisms limit the success of this approach. Both apoptosis and autophagy have been shown to contribute to this resistance. Prodigiosin, a secondary metabolite from various bacteria, exerts different biological activities including the modulation of these two cellular stress response pathways. We analyzed the effect of prodigiosin on protein levels of different autophagy- and apoptosis-related proteins in cisplatin-sensitive and -resistant urothelial carcinoma cells (UCCs). Furthermore, we investigated the effect on cell viability of prodigiosin alone or in combination with cisplatin. We made use of four different pairs of cisplatin-sensitive and -resistant UCCs. We found that prodigiosin blocked autophagy in UCCs and re-sensitized cisplatin-resistant cells to apoptotic cell death. Furthermore, we found that prodigiosin is a potent anticancer agent with nanomolar IC₅₀ values in all tested UCCs. In combination studies, we observed that prodigiosin sensitized both cisplatin-sensitive and -resistant urothelial carcinoma cell lines to cisplatin treatment with synergistic effects in most tested cell lines. These effects of prodigiosin are at least partially mediated by altering lysosomal function, since we detected reduced activities of cathepsin B and L. We propose that prodigiosin is a promising candidate for the therapy of cisplatin-resistant urothelial carcinomas, either as a single agent or in combinatory therapeutic approaches.     

Chemical imaging of glucose by CARS microscopy

Glucose is one of the most fundamental molecules within life and bioengineering sciences. Present understanding of its role in cellular and bioengineering processes relies primarily on invasive, large‐scale biochemical analysis, providing no spatial information on glucose pools or fluxes. This work identifies an emerging microscopy technique based on coherent anti‐Stokes Raman scattering (CARS), which fulfills the need of quantitative imaging of glucose at the single‐cell level with submicrometer resolution. No sample preparation with reporter molecules is required, ensuring that the low‐weight metabolite is studied under natural conditions. The potential of CARS microscopy is illustrated by quantitatively mapping glucose fluxes and distributions in a microfluidic bioreactor and in lipid‐bilayer vesicles, the latter as a model for glucose transmembrane transport. Furthermore, the metabolic response to a glucose pulse was monitored in living yeast cells. This study signifies a new era within CARS microscopy for its use of monitoring carbohydrates, in particular glucose which is one of the most abundant molecules in nature. Copyright © 2010 John Wiley & Sons, Ltd.