A bacterial cellulose (BC) nanofibril network is modified with an electrically conductive polyvinylaniline/polyaniline (PVAN/PANI) bilayer for construction of potential electrochemical biosensors. ...This is accomplished through surface-initiated atom transfer radical polymerization of 4-vinylaniline, followed by in situ chemical oxidative polymerization of aniline. A uniform coverage of the BC nanofiber with 1D supramolecular PANI nanostructures is confirmed by Fourier transform infrared, X-ray diffractogram, and CHN elemental analysis. Cyclic voltammograms evince the switching in the electrochemical behavior of BC/PVAN/PANI nanocomposites from the redox peaks at 0.74 V, in the positive scan and at −0.70 V, in the reverse scan, (at 100 mV·s–1 scan rate). From these redox peaks, PANI is the emeraldine form with the maximal electrical performance recorded, showing charge-transfer resistance as low as 21 Ω and capacitance as high as 39 μF. The voltage-sensible nanocomposites can interact with neural stem cells isolated from the subventricular zone (SVZ) of the brain, through stimulation and characterization of differentiated SVZ cells into specialized and mature neurons with long neurites measuring up to 115 ± 24 μm length after 7 days of culture without visible signs of cytotoxic effects. The findings pave the path to the new effective nanobiosensor technologies for nerve regenerative medicine, which demands both electroactivity and biocompatibility.
Growing evidence suggests an increasing significance for the extent of gastrointestinal tract (GIT) dysfunction in Parkinson's disease (PD). Most patients suffer from GIT symptoms, including ...dysphagia, sialorrhea, bloating, nausea, vomiting, gastroparesis, and constipation during the disease course. The underlying pathomechanisms of this α-synucleinopathy play an important role in disease development and progression, i.e., early accumulation of Lewy pathology in the enteric and central nervous systems is implicated in pharyngeal discoordination, esophageal and gastric motility/peristalsis impairment, chronic pain, altered intestinal permeability and autonomic dysfunction of the colon, with subsequent constipation. Severe complications, including malnutrition, dehydration, insufficient drug effects, aspiration pneumonia, intestinal obstruction, and megacolon, frequently result in hospitalization. Sophisticated diagnostic tools are now available that permit more detailed examination of specific GIT impairment patterns. Furthermore, novel treatment approaches have been evaluated, although high-level evidence trials are often missing. Finally, the burgeoning literature devoted to the GIT microbiome reveals its importance for neurologists. We review current knowledge about GIT pathoanatomy, pathophysiology, diagnosis, and treatment in PD and provide recommendations for management in daily practice.
Recently, chemoselective methods for the hydrogenation of fluorinated, silylated, and borylated arenes have been developed providing direct access to previously unattainable, valuable products. ...Herein, a comprehensive study on the employed rhodium-cyclic (alkyl)(amino)carbene (CAAC) catalyst precursor is disclosed. Mechanistic experiments, kinetic studies, and surface-spectroscopic methods revealed supported rhodium(0) nanoparticles (NP) as the active catalytic species. Further studies suggest that CAAC-derived modifiers play a key role in determining the chemoselectivity of the hydrogenation of fluorinated arenes, thus offering an avenue for further tuning of the catalytic properties.
Superficial success: A chiral N‐heterocyclic carbene (NHC*) is used to modify Fe3O4/Pd nanoparticles, which then catalyze asymmetric α‐arylations. This successful synthesis of a heterogeneous ...catalyst and its appliation in asymmetric catalysis is in stark contrast to the simple immobilization of an established chiral homogeneous catalyst.
N‐Heterocyclic carbenes (NHCs), which react with the surface of Au electrodes, have been successfully applied in pentacene transistors. With the application of NHCs, the charge‐carrier mobility of ...pentacene transistors increased by five times, while the contact resistance at the pentacene–Au interface was reduced by 85 %. Even after annealing the NHC–Au electrodes at 200 °C for 2 h before pentacene deposition, the charge‐carrier mobility of the pentacene transistors did not decrease. The distinguished performance makes NHCs as excellent alternatives to thiols as metal modifiers for the application in organic field‐effect transistors (OFETs).
Coated gold: N‐Heterocyclic carbenes (NHC) have been successfully applied to modify the surfaces of Au electrodes in organic field‐effect transistors (OFETs). The greatly improved transistor performance and excellent thermal stability in air indicate that NHCs are excellent alternatives to thiols as metal modifiers for application in OFETs.
Using femtosecond time-resolved x-ray diffraction, we directly monitor the coherent lattice dynamics through an ultrafast charge-density-wave-to-metal transition in the prototypical Peierls system ...K(0.3)MoO(3) over a wide range of relevant excitation fluences. While in the low fluence regime we directly follow the structural dynamics associated with the collective amplitude mode; for fluences above the melting threshold of the electronic density modulation we observe a transient recovery of the periodic lattice distortion. We can describe these structural dynamics as a motion along the coordinate of the Peierls distortion triggered by the prompt collapse of electronic order after photoexcitation. The results indicate that the dynamics of a structural symmetry-breaking transition are determined by a high-symmetry excited state potential energy surface distinct from that of the initial low-temperature state.
Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has been established as a powerful technique for the determination of metal and nonmetal distributions within biological ...systems with high sensitivity. An imaging LA-ICP-MS technique for Fe, Cu, Zn, and Mn was developed to produce large series of quantitative element maps in native brain sections of mice subchronically intoxicated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridin (MPTP) as a model of Parkinson's disease. Images were calibrated using matrix-matched laboratory standards. A software solution allowing a precise delineation of anatomical structures was implemented. Coronal brain sections were analyzed crossing the striatum and the substantia nigra, respectively. Animals sacrificed 2 h, 7 d, or 28 d after the last MPTP injection and controls were investigated.
We observed significant decreases of Cu concentrations in the periventricular zone and the fascia dentata at 2 h and 7d and a recovery or overcompensation at 28 d, most pronounced in the rostral periventricular zone (+40%). In the cortex Cu decreased slightly to −10%. Fe increased in the interpeduncular nucleus (+40%) but not in the substantia nigra. This pattern is in line with a differential regulation of periventricular and parenchymal Cu, and with the histochemical localization of Fe, and congruent to regions of preferential MPTP binding described in the rodent brain.
The LA-ICP-MS technique yielded valid and statistically robust results in the present study on 39 slices from 19 animals. Our findings underline the value of routine micro-local analytical techniques in the life sciences and affirm a role of Cu availability in Parkinson's disease.
Quantitation in 18 animals showed a time profile of periventricular Cu paralleling the course of classical dopaminergic markers at 2 h, 7 d, and 28 d.
Insufficient and heterogeneous oxygen (O2) distribution within engineered tissues results in hypoxic conditions. Hypoxia is one of the characteristics of solid tumors. To date, very few studies have ...used an O2-deliverable injectable hydrogel for cancer treatment under hypoxic conditions. In this field, we describe a new O2-carrying nanomaterial and an injectable nanocomposite hydrogel (PMOF and AlgL-PMOF, respectively) that can provide extended oxygen levels for cell survival under hypoxia. Particularly, PMOF and AlgL-PMOF enhance cell viability under hypoxic and normoxic cell culturing conditions. Moreover, sustained oxygen availability in the presence of an anticancer drug within the 3D network of AlgL-PMOF results in a decrease in the viability of malignant and immortal cells, while the viability of healthy cells increases.
•1H NMR fingerprinting allows to discriminate Colombian from all other coffees.•Samples are prepared in non-deuterated methanol.•Spectra are acquired using automatic suppression of solvent peaks.
The ...determination of the origin of coffee beans by NMR fingerprinting has been shown promising and classification has been reported for samples of different countries and continents. Here we show that this technique can be extended and applied to discriminate coffee samples from one country against all others, including its closest neighbors. Very high classification rates are reported using a large number of spectra (>300) acquired over a two-year period. As original aspects it can be highlighted that this study was performed in fully automatic mode and with non-deuterated coffee extracts. This is achieved using a series of experiments to procure a robust suppression of the solvent peaks. As is, the method represents a cost effective opportunity for countries to protect their national productions.
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