Single-cell calcium monitoring of Caco-2 cell co-cultured with intestinal microbiome through carbon fiber based potentiometric microelectrode.

The Caco-2 cells were used as intestinal epithelial cell model to illustrate the hyperuricemia (HUA) mechanism under the co-culture of the imbalanced intestinal microbiome in this work. The uric acid (UA) concentration in the HUA process was monitored, and could be up to 425 µmol/L at 8 h co-cultured with the imbalanced intestinal microbiome. Single-cell potentiometry based on ion-selective microelectrode was used to study extracellular calcium change, which is hypothesized to play an important role in the UA excretion. The potential signal of the calcium in the extremely limited microenvironment around single Caco-2 cell was recorded through the single-cell analysis platform. The potential signal of sharp decrease and slow increase followed within a few seconds indicates the sudden uptake and gradually excretion process of calcium through the cell membrane. Moreover, the value of the potential decrease increases with the increase of the time co-cultured with the imbalanced intestinal microbiome ranging from 0 to 8 h. The Ca2+ concentration around the cell membrane could decrease from 1.3 mM to 0.4 mM according to the potential decrease of 27.0 mV at the co-culture time of 8 h. The apoptosis ratio of the Caco-2 cells also exhibits time dependent with the co-culture of the imbalanced intestinal microbiome, and was 39.1 ± 3.6 % at the co-culture time of 8 h, which is much higher than the Caco-2 cells without any treatment (3.9 ± 2.9 %). These results firstly provide the links between the UA excretion with the apoptosis of the intestinal epithelial cell under the interaction of the imbalanced intestinal microbiome. Moreover, the apoptosis could be triggered by the calcium signaling.

Pharmacokinetics and Oral Bioavailability of Panax Notoginseng Saponins Administered to Rats Using a Validated UPLC-MS/MS Method.

Panax notoginseng saponins (PNS) are the most important bioactive components of P. Notoginseng. In this paper, an evaluation of the pharmacokinetics and oral absolute bioavailability of PNS was carried out following intravenous and oral administration of PNS to Sprague-Dawley rats. The plasma concentration of 28 PNS was determined using a validated UPLC-MS/MS system. The results demonstrated that Rb1(32.8%), Rg1(41.4%), R1(9.4%), Re(4.5%), and Rd(3.5%) are the five main ingredients of PNS for administration. After oral administration, it was found that the area under the curve (AUC0-72 h) for these five major saponins was significantly different. AUC0-72 h of Rb1 and Rd accounted for about 60% of all PNS exposure, while AUC0-72 h of Rg1 and R1 only accounted for 0.7%, and Re was undetectable in plasma. Also, PPD, PPT, and CK were detected as the major PNS metabolites in vivo. Furthermore, it was shown that the total oral bioavailability of PNS was only 1.2%.

Design, synthesis, and biological evaluation of triazole-pyrimidine-methylbenzonitrile derivatives as dual A2A/A2B adenosine receptor antagonists.

A series of novel dual A2A/A2B AR antagonists based on the triazole-pyrimidine-methylbenzonitrile core were designed and synthesised. The A2A AR antagonist cAMP functional assay results were encouraging for most target compounds containing quinoline or its open-ring bioisosteres. In addition, compound 7i displayed better inhibitory activity on A2B AR (IC50 14.12 nM) and higher potency in IL-2 production than AB928. Moreover, molecular docking studies were carried out to explain the rationality of molecular design and the activity of compound 7i. Further studies on 7f and 7i revealed good liver microsomes stabilities and acceptable in vivo PK profiles. This study provides insight into the future development of dual A2A/A2B AR antagonists for cancer immunotherapy.

Enhanced Intramuscular Bioavailability of Cannabidiol Using Nanocrystals: Formulation, In Vitro Appraisal, and Pharmacokinetics.

Cannabidiol (CBD) has poor water solubility and is subjected to extensive first-pass metabolism. These absorption obstacles are responsible for low and variable oral bioavailability of CBD. This study endeavored to improve CBD bioavailability by intramuscular (IM) injection of CBD nanocrystals (CBD-NC). The nanocrystals were prepared by antisolvent precipitation method and were characterized in terms of the particle size, polydispersity index (PDI), zeta potential, morphology, and crystalline status. CBD-NC displayed a particle size of 141.7±1.5 nm, a PDI of 0.18±0.01, and a zeta potential of -25.73 mV. CBD-NC freeze-dried powder using bovine serum albumin (BSA) as cryoprotectant had good redispersibility, and the average particle size was 139.1±1.4 nm after reconstitution. Moreover, these freeze-dried powders were characterized for drug loading and pH and were evaluated for in vitro dissolution and in vivo studies in a rat model. The in vivo results showed that AUC0-24 h and Cmax of CBD by IM injection of CBD nanocrystals increased significantly compared with that of oral (P.O) administration of CBD nanocrystals and CBD oil solution. This underlines the nano-sized CBD could be suggested as a practical and simple nanosystem for IM delivery with improved bioavailability. More importantly, these results pave the way for future development of CBD-NC retentive dosage forms. Graphical abstract.

The data of an all-solid-state acupuncture needle based potentiometric microelectrode for in vivo monitoring of calcium ions in rat cerebrospinal fluid.

These data contain the details of the fabrication of the calcium ion-selective microelectrode (Ca2+-ISµEs) modified with poly(3,4-ethylenedioxythiophene)-poly(sodium 4-styrenesulfonate) (PEDOT(PSS)) as solid contact. The electrochemical impedance spectroscopy was carried out for the investigation of the resistance of the Ca2+-ISµEs. The thickness of the solid contact and the calcium ion-selective membrane was investigated by SEM. Potential-time curve of the electrodeposition of the PEDOT/PSS film onto the surface of the microelectrodes under the applied current of 0.5 µA for 200 s was recorded. The proposed Ca2+-ISµE was optimized through conditioning in different CaCl2 solutions ranged from 1.0 × 10-6 to 3.1 × 10-3 M for different time before use. The anti-fouling property of the Ca2+-ISµEs against proteins was investigated through taking BSA as the model protein. The developed Ca2+-ISµEs were used for the in vivo monitoring of the calcium ions in rat cerebrospinal fluid under the stimuli of the spinal cord transection in a living animal.

In vivo monitoring of calcium ions in rat cerebrospinal fluid using an all-solid-state acupuncture needle based potentiometric microelectrode.

Acupuncture needles are regarded as ideal materiel for the development of microelectrodes for in vivo sensing. In this work, an all-solid-state ion-selective microelectrode (ISµE) has been developed by coating a calcium ion-selective membrane on an acupuncture needle tip with a diameter of less than 80 µm, which is modified with poly(3,4-ethylenedioxythiophene)-poly(sodium 4-styrenesulfonate) as solid contact. The proposed Ca2+-ISµE shows a Nernstian response toward Ca2+ in the range from 1.0 × 10-6 to 3.1 × 10-3 M with a slope of 30.8 ± 0.9 mV/decade (R2 = 0.999), and the detection limit is 1.2 × 10-7 M. The Ca2+-ISµE has been used for in vivo monitoring of the calcium changes in rat cerebrospinal fluid (CSF) under the injury of spinal cord transection. The results demonstrate that the calcium concentration in CSF increases sharply from the normal level of 20.6 ± 1.72 µM (n = 3) to 133.2 ± 7.63 µM (n = 3) with a severe fluctuation after spinal cord damage. Thus, the proposed Ca2+-ISµE is available for in vivo monitoring of calcium ions with high temporal resolution and flexibility. The detection system can be extended to measure other ions in CSF by changing different ion-selective membranes.

Strepyrazinone, a tricyclic diketopiperazine derivative with cytotoxicity from a marine-derived actinobacterium.

Strepyrazinone (1), a tricyclic diketopiperazine derivative with a carbon skeleton unprecedented in natural products, was isolated from the marine-derived Streptomyces sp. B223. Its structure was elucidated by spectroscopic analyses and electronic circular dichroism calculation. Compound 1 showed cytotoxic activity against HCT-116 cancer cell lines with an IC50 value of 0.34 µM.

Isolation, stereochemical study, and racemization of (±)-pratenone A, the first naturally occurring 3-(1-naphthyl)-2-benzofuran-1(3H)-one polyketide from a marine-derived actinobacterium.

(±)-Pratenone A (1), the first representative of natural 3-(1-naphthyl)-2-benzofuran-1(3H)-one polyketides, was isolated from a marine-derived Streptomyces pratensis strain KCB-132 together with three other new analogues (2-4). Its structure was assigned by spectroscopic analysis, and the absolute configurations of the two enantiomers separated by high-performance liquid chromatography were determined by single-crystal X-ray diffraction and electronic circular dichroism calculations. The solvent-induced racemization of 1 and a proposed biogenetic pathway to 1-4 from the co-isolated angucyclinone precursor, as well as their biological activity, are also discussed.

Determination of the Total Phenolic Content in Wine Samples Using Potentiometric Method Based on Permanganate Ion as an Indicator.

A rapid and accurate determination method for total phenolic content is of great importance for controlling the quality of wine samples. A promising potentiometric detection approach, based on permanganate ion fluxes across ion-selective electrode membranes, is fabricated for measuring the total phenolic content of wine. The results show that the presence of phenols, such as gallic acid, leads to a potential increase for the potentiometric sensor. Additionally, the present sensor exhibits a linear potential response with the concentration range from 0.05 to 3.0 g/L with a detection limit of 6.6 mg/L calculated using gallic acid. These sensors also exhibit a fast response time, an acceptable reproducibility and long-term stability. These results indicate that the proposed potentiometric sensor can be a promising and reliable tool for the rapid determination of total phenolic content in wine samples.

[Determination of tetrabromobisphenol A and bisphenol A in environmental water using carboxylated multiwalled carbon nanotubes as sorbent for solid-phase extraction combined with liquid chromatography-tandem mass spectrometry].

A method for the determination of tetrabromobisphenol A and bisphenol A in environmental water using carboxyl-functionalized multiwalled carbon nanotubes as solid-phase extraction sorbent and liquid chromatography-tandem mass spectrometry was established. Comparison of three nanomaterials including multiwalled carbon nanotubes, C60 and carboxyl-functionalized multiwalled carbon nanotubes used as solid-phase extraction sorbents was made. After preconcentration by solid-phase extraction, tetrabromobisphenol A and bisphenol A were separated on a Thermo Scientific Hypersil C18 column (150 mm x 4. 6 mm, 3 µm) and then detected by tandem mass spectrometry in negative electrospray ionization (ESI) mode. The results showed a good linear response in the concentration range of 0. 02-1. 0 mg/L for tetrabromobisphenol A and bisphenol A, and the limits of detection (S/N= 3) were 0. 04 pg/L and 0. 2 µg/L for tetrabromobisphenol A and bisphenol A, respectively. The application of the proposed approach has been carried out for the determination of tetrabromobisphenol A and bisphenol A in spiked lake water and sea water samples. The recoveries varied from 82% to 99% with the relative standard deviations below 5. 0%. The proposed method can be used for the determination of tetrabromobisphe- nol A and bisphenol A at trace level in complex environmental samples.

A potentiometric flow biosensor based on ammonia-oxidizing bacteria for the detection of toxicity in water.

A flow biosensor for the detection of toxicity in water using the ammonia-oxidizing bacterium (AOB) Nitrosomonas europaea as a bioreceptor and a polymeric membrane ammonium-selective electrode as a transducer is described. The system is based on the inhibition effects of toxicants on the activity of AOB, which can be evaluated by measuring the ammonium consumption rates with the ammonium-selective membrane electrode. The AOB cells are immobilized on polyethersulfone membranes packed in a holder, while the membrane electrode is placed downstream in the flow cell. Two specific inhibitors of the ammonia oxidation-allylthiourea and thioacetamide-have been tested. The IC50 values defined as the concentration of an inhibitor causing a 50% reduction in the ammonia oxidation activity have been measured as 0.17 µM and 0.46 µM for allylthiourea and thioacetamide, respectively. The proposed sensor offers advantages of simplicity, speed and high sensitivity for measuring toxicity in water.

Potentiometric sensor for determination of neutral bisphenol A using a molecularly imprinted polymer as a receptor.

The aim of this paper is to develop a potentiometric sensing methodology for sensitive and selective determination of neutral phenols by using a molecularly imprinted polymer as a receptor. Bisphenol A (BPA), a significant environmental contaminant, is employed as the model target. The BPA-imprinted polymer is synthesized by the semi-covalent technique and incorporated into a plasticized poly(vinyl chloride) membrane doped with the tridodecylmethylammonium salt. The present electrode shows a linear anionic potential response over the concentration range from 0.1 to 1 µM with a detection limit of 0.02 µM, and exhibits an excellent selectivity over other phenols. The proposed approach has been successfully applied to the determination of BPA released from real plastic samples. It offers promising potential in development of potentiometric sensors for measuring neutral phenols at trace levels.

[Matrix solid-phase dispersion and gas chromatography/mass spectrometry for the determination of phthalic acid esters in vegetables].

A method based on matrix solid-phase dispersion (MSPD) and gas chromatography/mass spectrometry (GC/MS) to determine dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), butylbenzyl phthalate (BBP) and di-2-ethylhexyl phthalate (DEHP) in vegetables was developed. The method, which required Florisil as solid dispersion sorbent, graphitized carbon black as purificant and ethyl acetate as eluting solvent, is simple, fast and suitable for the preparation of a large number of samples. The results showed that linearity of response over the five phthalic acid esters was good from 0.05 to 10.00 mg/kg. The recoveries of spiked samples ranging from 76% to 90% and the relative standard deviations ranging from 2% to 7% were obtained. The limits of detection for the method were from 0.01 to 0.024 mg/kg.