Protocol for calcium imaging and analysis of hippocampal CA1 activity evoked by non-spatial stimuli.

The hippocampus has a major role in processing spatial information but has been found to encode non-spatial information from multisensory modalities in recent studies. Here, we present a protocol for recording non-spatial stimuli (visual, auditory, and a combination) that evoked calcium activity of hippocampal CA1 neuronal ensembles in C57BL/6 mice using a miniaturized fluorescence microscope. We describe steps for experimental apparatus setup, surgical procedures, software development, and neuronal population activity analysis. For complete details on the use and execution of this protocol, please refer to Sun et al.1.

Dual Extracellular Recordings in the Mouse Hippocampus and Prefrontal Cortex.

The technique of recording local field potentials (LFPs) is an electrophysiological method used to measure the electrical activity of localized neuronal populations. It serves as a crucial tool in cognitive research, particularly in brain regions like the hippocampus and prefrontal cortex. Dual LFP recordings between these areas are of particular interest as they allow the exploration of interregional signal communication. However, methods for performing these recordings are rarely described, and most commercial recording devices are either expensive or lack adaptability to accommodate specific experimental designs. This study presents a comprehensive protocol for performing dual-electrode LFP recordings in the mouse hippocampus and the prefrontal cortex to investigate the effects of antipsychotic drugs and potassium channel modulators on LFP properties in these areas. The technique enables the measurement of LFP properties, including power spectra within each brain region and coherence between the two. Additionally, a low-cost, custom-designed recording device has been developed for these experiments. In summary, this protocol provides a means to record signals with high signal-to-noise ratios in different brain regions, facilitating the investigation of interregional information communication within the brain.

Intermolecular Interactions and Electrochemical Studies on Highly Concentrated Acetate-Based Water-in-Salt and Ionic Liquid Electrolytes.

Water-in-salt electrolytes constitute a new class of materials that have distinct properties relative to lower-concentration solutions. A recent approach to further increase the salt concentration and decrease the water content includes the addition of an ionic liquid to a highly concentrated aqueous solution. However, the physicochemical and electrochemical properties of aqueous lithium acetate-1-ethyl-3-methylimidazolium acetate solutions as well as the molecular interactions between electrolyte species have not been characterized. Here, we investigate these properties by evaluation of the ionic conductivity, viscosity, and thermal properties as well as the electrochemical behavior of various electrodes in these electrolytes. The intermolecular interactions are probed by nuclear magnetic resonance and infrared spectroscopies. We find that the addition of the ionic liquid increases the solubility limit of lithium acetate and that with an increase in both acetate salt and ionic liquid concentration in the electrolyte and decrease in water concentration, a strong acetate-water network is formed. The electrochemical stability window increases upon addition of the ionic liquid and reaches a value larger than 5 V for a set of negative Al and positive Ti electrodes in the highest acetate salt/ionic liquid concentration. Preliminary electrochemical charge storage performance measurements of a symmetric device based on two porous carbon electrodes cycled at a current density of 25 mA g-1 delivered a specific capacitance of 20 F g-1 with a Coulombic efficiency higher than 99% using a 1.8 V voltage window.

Sodium Hexa-Titanate Nanowires Modified with Cobalt Hydroxide Quantum Dots as an Efficient and Cost-Effective Electrocatalyst for Hydrogen Evolution in Alkaline Media.

A novel electrocatalyst with high activity and enhanced durability toward the hydrogen evolution reaction (HER) in alkaline media has been designed and fabricated based on sodium hexa-titanate (Na2Ti6O13) nanowires synthesized by a hydrothermal process and modified with Co(OH)2 quantum dots (QDs) by a facile chemical bath deposition (CBD) method. The current response of the developed Ti/Na2Ti6O13/Co(OH)2 nanocomposite electrode attained 10 mA cm-2 at an overpotential of 159 mV. The nanocomposite electrode exhibited a high stability at an applied current of 100 mA cm-2. The remarkable catalytic behavior was achieved with a loading amount of ca. 0.06 mg cm-2 cobalt hydroxide. This is attributed to the high electrochemically active surface area (EASA) gained by the nanowire-structured substrate and considerable enhancement of electrochemical conductivity with the use of Co(OH)2 quantum dots as an active material. The superior catalytic activity and high stability show that the developed catalyst is a promising candidate for hydrogen production in alkaline media.

Physicochemical and Electrochemical Properties of Water-in-Salt Electrolytes.

Aqueous electrolytes are attractive for applications in electrochemical technologies due to features like being eco-friendly, cost effective, and non-flammable. Very recently, superconcentrated aqueous electrolytes, such as so-called water-in-salt, water-in-bisalt, and hydrate melt, have received a significant attention for electrochemical energy storage due to enhanced stability and much wider electrochemical stability window. This Review focuses on the physicochemical properties of the highly concentrated electrolytes that are derived from several analysis techniques and simulation. A summary of most common features such as ions-water interactions, structure of species present in the electrolyte, conductivity, and viscosity of the electrolytes found in the literature are presented as well. In addition, this Review explains how these characteristics affect the electrochemical behavior of the electrolyte such as double layer structure and electrode/electrolyte interface leading to enhanced electrochemical stability of aqueous electrolytes.

Carbazole-Cyanobenzene Dyes Electrografted to Carbon or Indium-Doped Tin Oxide Supports for Visible Light-Driven Photoanodes and Olefin Isomerizations.

The organic carbazole-cyanobenzene push-pull dye 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene was derivatized and attached to carbon or indium-doped tin oxide (ITO) electrodes by simple diazonium electrografting. The surface-bound dye is active and stable for the visible light photosynthetic isomerization of a wide range of functionalized stilbene and cinnamic acid derivatives. Up to 87,000 net turnovers were obtained for the isomerization of trans-stilbene. The isomerizations can be carried out in air with a 33% reduction in the rate. The ITO photoelectrodes are also active and stable toward photo-oxidations under basic and acidic conditions.

Anti-aging Klotho Protects SH-SY5Y Cells Against Amyloid ß1-42 Neurotoxicity: Involvement of Wnt1/pCREB/Nrf2/HO-1 Signaling.

Alzheimer's disease (AD) is considered a prevalent neurological disorder with a neurodegenerative nature in elderly people. Oxidative stress and neuroinflammation due to amyloid ß (Aß) peptides are strongly involved in AD pathogenesis. Klotho is an anti-aging protein with multiple protective effects that its deficiency is involved in development of age-related disorders. In this study, we investigated the beneficial effect of Klotho pretreatment at different concentrations of 0.5, 1, and 2 nM against Aß1-42 toxicity at a concentration of 20 µM in human SH-SY5Y neuroblastoma cells. Our findings showed that Klotho could significantly and partially restore cell viability and decrease reactive oxygen species (known as ROS) and improve superoxide dismutase activity (SOD) in addition to reduction of caspase 3 activity and DNA fragmentation following Aß1-42 challenge. In addition, exogenous Klotho also reduced inflammatory biomarkers consisting of nuclear factor-kB (NF-kB), interleukin-1ß (IL-1ß), and tumor necrosis factor-α (TNF-α) in Aß-exposed cells. Besides, Klotho caused downregulation of Wnt1 level, upregulation of phosphorylated cyclic AMP response element binding (pCREB), and mRNA levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase 1 (HO-1) with no significant alteration of epsilon isoform of protein kinase C (PKCε) after Aß toxicity. In summary, Klotho could alleviate apoptosis, oxidative stress, and inflammation in human neuroblastoma cells after Aß challenge and its beneficial effect is partially exerted through appropriate modulation of Wnt1/pCREB/Nrf2/HO-1 signaling.

Solid-phase synthesis and photoactivity of Ru-polypyridyl visible light chromophores bonded through carbon to semiconductor surfaces.

1,10-Phenanthroline (phen) was grafted to either indium tin oxide (ITO), fluorine-doped tin oxide (FTO), or titanium dioxide (TiO2) semiconductors (SC's) by electrochemical reduction of 5-diazo-phen. The phen ligand is bonded to the semiconductor at C5, and it can be handled in air. The semiconductor-phen (SC-phen) complexes displace both CH3CN ligands from either cis-[Ru(Mebipy)2(CH3CN)2]2+ (Mebipy = 4,4'-methyl-2,2'-bipyridine), cis-[Ru(tBubipy)2(CH3CN)2]2+ (tBubipy = 4,4'-tert-butyl-2,2'-bipyridine), or cis-[Ru(pheno)(bipy)(CH3CN)2]2+ (bipy = 2,2'-bipyridine; pheno = 1,10-phenanthroline-5,6-dione) dissolved in DCM/THF (4 h, 70 °C) to form the corresponding surface-bound SC-[(phen)Ru(bipyridyl)2]2+ chromophores. The identities of the SC-[(phen)Ru(Mebipy)2]2+, SC-[(phen)Ru(tBubipy)2]2+, and SC-[(phen)Ru(pheno)(bipy)]2+ (SC = ITO, FTO or TiO2) chromophores were confirmed by X-ray photoelectron spectroscopy (XPS); inductively coupled plasma mass spectrometry (ICP-MS); UV-vis and reflectance infrared spectroscopies; and cyclic voltammetry (CV). The data were compared to analogous Ru-polypyridyl control compounds dissolved in solution. A facile ketone-amine condensation solid-phase synthesis reaction between SC-[(phen)Ru(pheno)(bipy)]2+ and [Ru(1,10-phenthroline-5,6-diamine)(bipy)2]2+ in ethanol (80 °C, 1 h) formed the dinuclear, bound chromophore SC-[(phen)(bipy)Ru(tpphz)Ru(bipy)2]4+ (tpphz = tetrapyrido[3,2-a:2',3'-c:3'',2''-h:2''',3'''-j]phenazine). Photoelectrochemical oxidation of hydroquinone and triethylamine under acidic, neutral, or basic conditions showed that the SC-chromophore photoanodes are active, and that TiO2-[(phen)Ru(Mebipy)2]2+ is the most active and stable under basic- and neutral conditions. The dinuclear chromophore SC-[(phen)(bipy)Ru(tpphz)Ru(bipy)2]4+ was most active and stable under potentiostatic conditions in acid.

Modular Construction of Photoanodes with Covalently Bonded Ru- and Ir-Polypyridyl Visible Light Chromophores.

1,10-phenanthroline is grafted to indium tin oxide (ITO) and titanium dioxide nanoparticle (TiO2) semiconductors by electroreduction of 5-diazo-1,10-phenanthroline in 0.1 M H2SO4. The lower and upper potential limits (-0.20 and 0.15 VSCE, respectively) were set to avoid reduction and oxidation of the 1,10-phenanthroline (phen) covalently grafted at C5 to the semiconductor. The resulting semiconductor-phen ligand (ITO-phen or TiO2-phen) was air stable, and was bonded to Ru- or Ir- by reaction with cis-[Ru(bpy)2(CH3CN)2]2+ (bpy = 2,2'-bipyridine) or cis-[Ir(ppy)2(CH3CN)2]+ (ppy = ortho-Cphenyl metalated 2-phenylpyridine) in CH2Cl2 and THF solvent at 50 °C. Cyclic voltammetry, X-ray photoelectron spectroscopy, solid-state UV-vis, and inductively coupled plasma-mass spectrometry all confirmed that the chromophores SC-[(phen)Ru(bpy)2]2+ and SC-[(phen)Ir(ppy)2]+ (SC = ITO or TiO2) formed in near quantitative yields by these reactions. The resulting photoanodes were active and relatively stable to photoelectrochemical oxidation of hydroquinone and triethylamine under neutral and basic conditions.

Protective Effects of Fibroblast Growth Factor 21 Against Amyloid-Beta1-42-Induced Toxicity in SH-SY5Y Cells.

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the progressive loss of cholinergic neurons. Amyloid beta is a misfolded protein that represents one of the key pathological hallmarks of AD. Numerous studies have shown that Aß1-42 induces oxidative damage, neuroinflammation, and apoptosis, leading to cognitive decline in AD. Recently, fibroblast growth factor 21 (FGF21) has been suggested to be a potential regulator of oxidative stress in mammalian cells. FGF21 has been shown to improve insulin sensitivity, reduce hyperglycemia, increase adipose tissue glucose uptake and lipolysis, and decrease body fat and weight loss by enhancing energy expenditure. In this study, we investigated the effect of FGF21 Aß1-42 toxicity in SH-SY5Y neuroblastoma cells. Our data shows that FGF21 significantly decreased Aß1-42-induced toxic effects and repressed oxidative stress and apoptosis in cells exposed to Aß1-42 peptide. Our investigation also confirmed that FGF21 pretreatment favorably affects HSP90/TLR4/NF-κB signaling pathway. Therefore, FGF21 represents a viable therapeutic strategy to abrogate Aß1-42-induced cellular inflammation and apoptotic death in the SH-SY5Y neuroblastoma cells.

Bacterial protease triggered release of biocides from microspheres with an oily core.

This study deals with controlled release of drugs to a Staphylococcus aureus infected site from microspheres with an oily core and a polymeric shell. The intended use of the microspheres is for chronic wounds and the microspheres may be administered in the form of a wash liquid or incorporated in a gel. Chronic wounds often carry infection, and the use of microspheres with drug release triggered by the bacterial infection is therefore of interest. A lipophilic drug or a model of the drug was dissolved in an oil and the oil phase was dispersed into an o/w emulsion. A nanofilm shell was then assembled around the oil droplets with the layer-by-layer technique using the two biodegradable polypeptides anionic poly-L-glutamic acid (PLGA) and cationic poly-L-lysine (PLL). Since S. aureus exudes proteases such as glutamyl endopeptidase (V8) during colonization and infection, its substrate specificity was key when assembling the nanofilm. Since V8 is known to be substrate specific to the Glu-X bond, PLGA was chosen as the terminating layer of the nanofilm. Crosslinking the nanofilm after assembly lead to increased stability of the microspheres. It was shown that in a non-infectious environment, i.e. when a human wound enzyme, HNE (human neutrophile elastase), was present, the microspheres remained intact. The staphylococcal protease V8, on the other hand, readily catalyzed degradation of the microspheres, thus releasing the drug when triggered by the infectious environment.

Au nanoparticle/graphene nanocomposite as a platform for the sensitive detection of NADH in human urine.

Here we report on a facile, rapid, sensitive, selective and highly stable electrochemical sensing platform for ß-nicotinamide adenine dinucleotide (NADH) based on uncapped Au nanoparticle/reduced graphene oxide (rGO) nanocomposites without the aid of any redox mediators and enzymes. The Au nanoparticle/rGO composite sensing platform was directly formed on a glassy carbon electrode through an in situ electrochemical reduction of GO and Au(3+) with a 100% usage of the precursors. The as-prepared Au nanoparticle/rGO composites demonstrated excellent direct electrocatalytic oxidation toward NADH, providing a large electrochemical active surface area as well as a favorable environment for electron transfer from NADH to the electrode via the enhanced mobility of charge carriers. The Au nanoparticle/rGO composites offered a ~2.3 times higher electrocatalytic current density with a negative shift of 112mV, in comparison to Au nanoparticles. The sensor developed in this study displayed a high sensitivity of 0.916µA/µMcm(2) and a wide linear range of from 50nM to 500µM with a limit of detection of 1.13nM (S/N=3). The interferences from the common interferents such as glutathione, glucose, ascorbic acid and quanine were negligible. The prepared sensor was further tested for the determination of NADH in human urine samples, showing the Au nanoparticle/rGO nanocomposites simultaneously formed by one-step electrochemical reduction have promising biomedical applications.