Rapid and sensitive HPLC-MS/MS method for the quantification of dopamine, GABA, serotonin, glutamine and glutamate in rat brain regions after exposure to tobacco cigarettes

Square-shaped Cu2MoS4 loaded on three-dimensional flower-like AgBiS2 to form S-scheme heterojunction as a light-driven photoelectrochemical sensor for efficient detection of serotonin in biological samples

Serotonin (5-HT) is a crucial neurotransmitter in the body, with its levels being particularly significant for life safety. Here, we designed the AgBiS2/Cu2MoS4 S-scheme heterojunction by uniformly immobilizing lamellar Cu2MoS4 on the surface of three-dimensional (3D) flower-like AgBiS2 using a simple physical mixing technique. In this case, AgBiS2 and Cu2MoS4 are bonded together by electrostatic attraction to form an active surface with a large specific surface area. Subsequently, the detector 5-HT bound to AgBiS2/Cu2MoS4/GCE undergoes hole oxidation and the photocurrent signal increases significantly. Meanwhile, the reaction mechanism of AgBiS2/Cu2MoS4 composite material was investigated through density functional theory calculations. The AgBiS2/Cu2MoS4/GCE sensor demonstrates a low detection limit of 0.046 nM and a wide linear range (0.0001-8 μM). Furthermore, by comparing UV-Vis spectrophotometry and fluorescence spectroscopy for the detection of 5-HT in human serum, it was proved that the sensor has an impressive recovery rate.

Revealing the optimal traditional processing methods and its protective effects against febrile seizures of Arisaema cum bile

Arisaema cum bile (known as Dan Nanxing in Chinese, DNX) is a herbal medicine used for treating febrile seizure (FS), which commonly prepared by using Arisaematis Rhizoma and animal bile. This study was designed to explore the optimal processing time of DNX and its potential mechanism on the anti-FS effect. A total of 17 volatile organic compounds (VOCs) were the characteristic ones to distinguish different fermentation stages of DNX by using gas chromatography-ion mobility spectrometry (GC-IMS), such as 2-heptanone monomer, and heptanal monomer. DNX with fermentation for 3 months had an obvious pattern of VOCs with others, which could be regarded as the optimal fermentation time. The Enterococcus and Staphylococcus might be the core bacteria on the production of VOCs. Additionally, DNX (2.8 g/kg, p.o.) reversed hot water bath-induced FSs of rats, as indicated by increased seizure latency and decreased seizure duration time. It also prevented hippocampal neuronal loss, increased GABAAR, and decreased GRIA1 expression. At the genus level, relative abundance of Enterococcus and Akkermansia were enriched after DNX treatment. These findings suggested that fermentation for 3 months might be the optimal process time for DNX, and DNX possess an anti-FS effect through regulating neurotransmitter disorder and gut microbiota.

SERS detection of dopamine using metal-chelated Ag nanoshell

As the concentrations of different neurotransmitters can indicate the presence of certain disorders affecting brain functions, quantitative analyses of neurotransmitters have attracted increasing attention in various fields. Surface-enhanced Raman scattering (SERS) spectroscopy is an outstanding spectroscopic analytical tool that enables detection at the single molecule level with high specificity. As local field enhancement of surface plasmon is effective within nanometers, active interaction between SERS-active noble metals (gold and silver) and analyte molecules enhances the molecular detection capacity of SERS. However, neurotransmitters and noble metal nanoparticles are often not affinitive, because neurotransmitters generally have a hydroxyl group rather than a thiol group. As a result, the interaction between the two typically remains inactive, which makes detection more difficult. To overcome this limitation, in the present work we utilized metal-chelation to attract dopamine, a neurotransmitter molecule, close to the surface of silver nanoparticles. AgNS was capped with poly(vinyl alcohol) (PVA) and sequentially integrated with copper ion to bind dopamine in the form of chelate bonding between dopamine and copper. The PVA linked AgNS and metal ions through a coordinate bond between hydroxyl groups and metal ions. This metal-chelation-functionalized nanoprobe allowed us to stably detect dopamine in aqueous solution at a concentration of less than 10-6 M. Therefore, this method provides a convenient and easy-to-prepare option for the effective detection of dopamine, thus meaning it has the potential to be applied to other neurotransmitters.

New insight into interference-free and highly sensitive dopamine electroanalysis

Early diagnosis of Parkinson's disease and hyperprolactinemia based on electrochemical dopamine (DA) sensing appears as an efficient and promising practical diagnostic method. However, the coexistence of DA in real samples with ascorbic acid (AA) and uric acid (UA), which oxidize at potentials close to its own, prevents the accurate electrochemical DA sensing and therefore, hinders the effective diagnosis of these diseases. In this work, we successfully combined the electrostatic proprieties of GO, the electron transfer properties of an AuNPs@MWCNTs nanocomposite and the ability of thiol group of the amino acid l-cysteine to react chemically with carbonyl groups of UA, to develop a novel approach that enabled complete suppression of interference from AA and UA and hence, accurate DA electroanalysis in the conditions close to those of human blood serum. The chemical reaction between l-cysteine and UA was evidenced by monitoring the DPV responses of UA under different conditions. XRD, Raman spectroscopy, XPS and FE-SEM revealed the successful synthesis of GO and AuNPs@MWCNTs. The study of the electrode material (GO-AuNPs@MWCNTs) morphology via FE-SEM and HR-TEM showed that AuNPs@MWCNTs are distributed throughout the exfoliated GO layers. The fabricated sensor was calibrated in the concentration range of 0.5-5 μM, in the presence of the highest blood concentrations of AA and UA for healthy individuals. A linear relationship was observed and the LOD was found to be 1.31 nM (S/N = 3). Furthermore, the sensor showed good electron transfer kinetics, good repeatability and reproducibility, satisfactory long-term stability, and recoveries in human blood serum.

Effect of Cigarette Smoke Exposure and Aspirin Treatment on Neurotransmitters’ Tissue Content in Rats’ Hippocampus and Amygdala

Cigarette smoke withdrawal can cause anxiety-like behavior and modulate neurotransmitter-related proteins in the brain. We examined the effects of cigarette smoke with and without aspirin treatment on the concentrations of neurotransmitters, including dopamine, serotonin, glutamate, glutamine, and GABA in the amygdala and hippocampus. Sprague-Dawley rats were randomly assigned to four different groups: (1) control group exposed only to standard room air, (2) cigarette smoke exposed group treated with saline vehicle, (3) cigarette smoke exposed group treated with aspirin (30 mg/kg), and (4) control group treated only with aspirin (30 mg/kg). Cigarette smoke exposure was performed for 2 h/day, 5 days/week, for 31 days. Behavioral testing was carried out weekly, 24 h after cigarette smoke exposure, during acute withdrawal. At the end of week 4, rats were given either distilled water (1 mL) or aspirin 45 min before cigarette exposure for 11 days. Dopamine, serotonin, glutamate, glutamine, and GABA were extracted from both the amygdala and hippocampus and were separated and quantified using a developed and validated HPLC-MS/MS method. Cigarette smoke withdrawal induced anxiety behaviors, and aspirin treatment reduced this effect. Cigarette smoke exposure increased tissue content of dopamine, serotonin, glutamate, glutamine, and GABA, and aspirin treatment reversed this effect. Cigarette smoke caused an increase in tissue content of several neurotransmitters as well as anxiety-like behavior, and these effects were normalized by aspirin treatment.