Nanocrystalline SnO2 Functionalized with Ag(I) Organometallic Complexes as Materials for Low Temperature H2S Detection

This paper presents a comparative analysis of H2S sensor properties of nanocrystalline SnO2 modified with Ag nanoparticles (AgNPs) as reference sample or Ag organic complexes (AgL1 and AgL2). New hybrid materials based on SnO2 and Ag(I) organometallic complexes were obtained. The microstructure, compositional characteristics and thermal stability of the composites were thoroughly studied by X-ray diffraction (XRD), X-ray fluorescent spectroscopy (XRF), Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and Thermogravimetric analysis (TGA). Gas sensor properties to 2 ppm H2S demonstrated high sensitivity, selectivity toward other reducing gases (H2 (20 ppm), NH3 (20 ppm) and CO (20 ppm)) and good reproducibility of the composites in H2S detection at low operating temperatures. The composite materials also showed a linear detection range in the concentration range of 0.12–2.00 ppm H2S even at room temperature. It was concluded that the predominant factors influencing the sensor properties and selectivity toward H2S in low temperature region are the structure of the modifier and the chemical state of silver. Thus, in the case of SnO2/AgNPs reference sample the chemical sensitization mechanism is more possible, while for SnO2/AgL1 and SnO2/AgL2 composites the electronic sensitization mechanism contributes more in gas sensor properties. The obtained results show that composites based on nanocrystalline SnO2 and Ag(I) organic complexes can enhance the selective detection of H2S.

Synthesis and Characterization of a Nano (CdO)0.94:(In2O3) 0.06 / Si gas Sensor

In this work, a (CdO)0.94:(In2O3)0.06 film was developed on a glass substrate using Q- switching pulse laser beam (Nd:YAG; wavelength 1064 nm). The quantitative elemental analysis of the (CdO)0.94:(In2O3)0.06 thin film was achieved using energy dispersive X- ray diffraction (EDX). The topological and morphological properties of the deposited thin film were investigated using atomic force microscope (AFM) and field emission scan electron microscopy (FESEM). The I-V characteristic and Hall effect of (CdO)0.94 :(In2O3)0.06 thin films were used to study the electrical properties. The gas sensor properties of the film prepared on n-Si were investigated for oxidization and reduction gases.

Solvent Effect in Imidazole-Based Poly(Ionic Liquid) Membranes: Energy Storage and Sensing

Polymerized ionic liquids (PILs) are interesting new materials in sustainable technologies for energy storage and for gas sensor devices, and they provide high ion conductivity as solid polymer electrolytes in batteries. We introduce here the effect of polar protic (aqueous) and polar aprotic (propylene carbonate, PC) electrolytes, with the same concentration of lithium bis(trifluoromethane) sulfonimide (LiTFSI) on hydrophobic PIL films. Cyclic voltammetry, scanning ionic conductance microscopy and square wave voltammetry were performed, revealing that the PIL films had better electroactivity in the aqueous electrolyte and three times higher ion conductivity was obtained from electrochemical impedance spectroscopy measurements. Their energy storage capability was investigated with chronopotentiometric measurements, and it revealed 1.6 times higher specific capacitance in the aqueous electrolyte as well as novel sensor properties regarding the applied solvents. The PIL films were characterized with scanning electron microscopy, energy dispersive X-ray, FTIR and solid state nuclear magnetic resonance spectroscopy.

Structures, Bonding and Sensor Properties of Some Alkaline o-Phthalatocuprates

Comprehensive study of the structure and bonding of disodium, dipotassium and diammonium di-o-phthalatocuprates(II) dihydrates has been undertaken. The crystal structure of ammonium o-phthalatocuprate has been determined. The identity of structures of phthalatocuprate chains in potassium and ammonium salts has been revealed. Vibrational spectra of all three compounds have been recorded, and the assignment of vibrational bands has been made. Force field calculations have shown a minor effect of outer-sphere cations (Na+, K+, NH4+) on both intraligand (C-O) and metal–ligand bond strengths. Synthesized compounds have been tested as electrochemical sensors on D-glucose, dopamine and paracetamol. Their sensitivity to analytes varied in the order of Na+ > K+ > NH4+. This effect has been explained by the more pronounced steric hindrance of copper ions in potassium and ammonium salts.

Multimodal Detection of Dopamine by Sniffer Cells Expressing Genetically Encoded Fluorescence Sensors

Dopamine serves an important role in supporting both locomotor control and higher brain functions such as motivation and learning. Dopaminergic dysfunction is implicated in an equally multidimensional spectrum of neurological and neuropsychiatric diseases. Extracellular dopamine levels are known to be tightly controlled by presynaptic dopamine transporters (DAT), which is also a main target of psychostimulants. Still, detailed data on dopamine dynamics in space and time is needed to fully understand how dopamine signals are encoded and translated into cellular and behavioral responses, and to uncover the pathological effects of dopamine-related diseases. The recently developed genetically encoded fluorescent dopamine sensors enable unprecedented monitoring of dopamine dynamics and have changed the field of in vivo dopamine recording. However, the potential of these sensors to be used for in vitro and ex vivo assays remains unexplored. Here, we demonstrate a generalizable blueprint for making dopamine 'sniffer' cells for multimodal detection of dopamine in vitro and ex vivo. We generated sniffer cell lines with inducible expression of six different dopamine sensors and performed a head-to-head comparison of sensor properties to guide users in sensor selection. In proof-of-principle experiments, we show how the sniffer cells can be applied to measure release of endogenous dopamine from cultured neurons and striatal slices, and for determining total dopamine content in striatal tissue. Furthermore, we use the sniffer cells to quantify DAT-mediated dopamine uptake, and AMPH-induced and constitutive dopamine efflux as a radiotracer free, high-throughput alternative to electrochemical- and radiotracer-based assays. Importantly, the sniffer cells framework can readily be applied to other transmitter systems for which the list of genetically encoded fluorescent sensors is rapidly growing.

Metal Derivatives of Sulfonated Polyphenylquinoxaline

The polymer-analogous transformations of an aromatic ionogenic polymer, namely, sulfonated polyphenylquinoxaline afford a range of polymer salts bearing alkali (Li+, Na+, K+), alkaline earth (Mg2+, Са2+, Ba 2+), and transition di- (Cu2+, Ni2+, Zn2+) and trivalent (La3+, In3+) metal ions. The resulting polymers are characterized by elemental and thermogravimetric analyses. The solubility and rheological properties of their dilute and concentrated solutions as well as sensor properties of the coatings based on these polymer salts are explored.