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1.
Int J Mol Sci ; 22(11)2021 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-34063925

RESUMO

Today, the use of polymer electrolyte membranes (PEMs) possessing ionic liquids (ILs) in middle and high temperature polymer electrolyte membrane fuel cells (MT-PEMFCs and HT-PEMFCs) have been increased. ILs are the organic salts, and they are typically liquid at the temperature lower than 100 °C with high conductivity and thermal stability. The membranes containing ILs can conduct protons through the PEMs at elevated temperatures (more than 80 °C), unlike the Nafion-based membranes. A wide range of ILs have been identified, including chiral ILs, bio-ILs, basic ILs, energetic ILs, metallic ILs, and neutral ILs, that, from among them, functionalized ionic liquids (FILs) include a lot of ion exchange groups in their structure that improve and accelerate proton conduction through the polymeric membrane. In spite of positive features of using ILs, the leaching of ILs from the membranes during the operation of fuel cell is the main downside of these organic salts, which leads to reducing the performance of the membranes; however, there are some ways to diminish leaching from the membranes. The aim of this review is to provide an overview of these issues by evaluating key studies that have been undertaken in the last years in order to present objective and comprehensive updated information that presents the progress that has been made in this field. Significant information regarding the utilization of ILs in MT-PEMFCs and HT-PEMFCs, ILs structure, properties, and synthesis is given. Moreover, leaching of ILs as a challenging demerit and the possible methods to tackle this problem are approached in this paper. The present review will be of interest to chemists, electrochemists, environmentalists, and any other researchers working on sustainable energy production field.


Assuntos
Eletrólitos/química , Líquidos Iônicos/química , Polímeros/química , Animais , Condutividade Elétrica , Temperatura Alta , Humanos , Membranas Artificiais , Prótons
2.
Int J Mol Sci ; 22(9)2021 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-34067069

RESUMO

Banana (Musa spp.), one of the most important fruits worldwide, is generally cold sensitive. In this study, by using the cold-sensitive banana variety Tianbaojiao (Musa acuminate) as the study material, we investigated the effects of Piriformospora indica on banana cold resistance. Seedlings with and without fungus colonization were subjected to 4 °C cold treatment. The changes in plant phenotypes, some physiological and biochemical parameters, chlorophyll fluorescence parameters, and the expression of eight cold-responsive genes in banana leaves before and after cold treatment were measured. Results demonstrated that P. indica colonization reduced the contents of malondialdehyde (MDA) and hydrogen peroxide (H2O2) but increased the activities of superoxide dismutase (SOD) and catalase (CAT) and the contents of soluble sugar (SS) and proline. Noteworthily, the CAT activity and SS content in the leaves of P. indica-colonized banana were significant (p < 0.05). After 24 h cold treatment, the decline in maximum photochemistry efficiency of photosystem II (Fv/Fm), photochemical quenching coefficient (qP), efficient quantum yield [Y(II)], and photosynthetic electron transport rate (ETR) in the leaves of P. indica-colonized banana was found to be lower than in the non-inoculated controls (p < 0.05). Moreover, although the difference was not significant, P. indica colonization increased the photochemical conversion efficiency and electron transport rate and alleviated the damage to the photosynthetic reaction center of banana leaves under cold treatment to some extent. Additionally, the expression of the most cold-responsive genes in banana leaves was significantly induced by P. indica during cold stress (p < 0.05). It was concluded that P. indica confers banana with enhanced cold resistance by stimulating antioxidant capacity, SS accumulation, and the expression of cold-responsive genes in leaves. The results obtained from this study are helpful for understanding the P. indica-induced cold resistance in banana.


Assuntos
Basidiomycota/fisiologia , Temperatura Baixa , Resistência à Doença , Endófitos/fisiologia , Musa/enzimologia , Basidiomycota/crescimento & desenvolvimento , Catalase/metabolismo , Clorofila/metabolismo , Contagem de Colônia Microbiana , Eletrólitos/metabolismo , Fluorescência , Regulação da Expressão Gênica de Plantas , Musa/genética , Musa/microbiologia , Peroxidase/metabolismo , Fenótipo , Folhas de Planta/enzimologia , Folhas de Planta/microbiologia , Folhas de Planta/fisiologia , Superóxido Dismutase/metabolismo
3.
Biomed Res Int ; 2021: 6667047, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33937408

RESUMO

The novel coronavirus disease 2019 (COVID-19) is the cause of an acute respiratory illness which has spread around the world. The virus infects the host by binding to the angiotensin-converting enzyme 2 (ACE2) receptors. Due to the presence of ACE2 receptors in the kidneys and gastrointestinal (GI) tract, kidneys and GI tract damage arising from the virus can be seen in patients and can cause acute conditions such as acute kidney injury (AKI) and digestive problems for the patient. One of the complications of kidneys and GI involvement in COVID-19 is fluid and electrolyte disturbances. The most common ones of these disorders are hyponatremia, hypernatremia, hypokalemia, hypocalcemia, hypochloremia, hypervolemia, and hypovolemia, which if left untreated, cause many problems for patients and even increase mortality. Fluid and electrolyte disturbances are more common in hospitalized and intensive care patients. Children are also at greater risk for fluid and electrolyte disturbances complications. Therefore, clinicians should pay special attention to the fluid and electrolyte status of patients. Changes in fluid and electrolyte levels can be a good indicator of disease progression.


Assuntos
Líquidos Corporais/metabolismo , COVID-19/etiologia , Eletrólitos/metabolismo , Injúria Renal Aguda/etiologia , COVID-19/complicações , Trato Gastrointestinal/fisiopatologia , Trato Gastrointestinal/virologia , Humanos , Hipocalcemia/etiologia , Hipopotassemia/etiologia , Hiponatremia/etiologia , Rim/fisiopatologia , Rim/virologia
4.
J Pak Med Assoc ; 71(3): 921-924, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-34057949

RESUMO

OBJECTIVE: To assess mothers' knowledge about the quantity of oral rehydration salt and zinc in the management of diarrhoea. METHODS: The cross-sectional study was conducted from May to August 2019 at The Children's Hospital, Lahore, Pakistan, and comprised mothers accompanying children aged <5 years admitted with diarrhoea complaints. Data was collected regarding demographics and mothers' awareness of signs of dehydration in diarrhoea, familiarity with the term oral rehydration salt, its correct preparation and administration and zinc supplementation. Data was analysed using SPSS 20. RESULTS: Of the 334 mothers interviewed, 154(46%) were able to identify the signs of dehydration. Maternal awareness regarding use of oral rehydration salt and zinc in diarrhoea were significantly associated with maternal education and socioeconomic status (p<0.05). CONCLUSIONS: There is a need to generate awareness among mothers about the use of oral rehydration salt and zinc in diarrhoea.


Assuntos
Mães , Zinco , Criança , Estudos Transversais , Diarreia/epidemiologia , Diarreia/terapia , Eletrólitos , Feminino , Humanos , Paquistão , Centros de Atenção Terciária , Zinco/uso terapêutico
5.
Anal Chim Acta ; 1166: 338547, 2021 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-34022999

RESUMO

Studying the role of buffers in impedance spectroscopy is a relatively unexplored area. We demonstrate a special class of biologically relevant buffers known as Good's zwitterionic buffers that show improved performance over standard electrolyte buffers (e.g. PBS) currently widely used in impedance spectroscopy measurements of bacterial suspensions. Our theoretical and experimental comparisons of conductivity of classical and zwitterionic buffers at various different concentrations show that ion-ion interaction effects are significantly higher in zwitterionic buffers as compared to classical buffers at the concentrations at which they are used. This and the fact that zwitterions have larger sizes leads to the lowering of their conductivity which significantly improves their impedance sensing ability. We illustrate through an example of heat-induced ionic release in model S. typhi and S. aureus bacteria that having a low conductivity buffer is indeed beneficial for biological impedance measurements. In fact, the best buffer for impedance studies can be chosen solely based on their electrical properties as long as they are also biologically compatible. This gives Good's zwitterionic buffers an edge over conventional media as they satisfy both these criteria.


Assuntos
Espectroscopia Dielétrica , Staphylococcus aureus , Tampões (Química) , Condutividade Elétrica , Eletrólitos
6.
Medicine (Baltimore) ; 100(20): e26016, 2021 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-34011103

RESUMO

ABSTRACT: To examine potential risk factors associated with biochemical alterations in renal function in a population diagnosed with HIV/AIDS undergoing antiretroviral treatment.This is an observational, transversal, and relational design study that included 179 HIV-seropositive subjects. Glucose serum, cholesterol, triglycerides, total proteins, albumin, creatine, urea, blood urea nitrogen (BUN), and electrolytes levels were determined for each individual. Renal function was evaluated through the glomerular filtration rate (GFR), using the CKD-EPI equation. Chronic kidney disease (CKD) was defined as estimated glomerular filtration rate  < 60 mL/min/1.73 m2. Univariate model significant variables, with a 95% confidence interval (CI), were included in a multivariate logistic regression analysis.CKD prevalence in patients was 7.3%, with comorbidities of 7.8% for type 2 diabetes mellitus, 7.3% for arterial hypertension, and 35.2% for dyslipidemia. Additionally, both hypernatremia and hypophosphatemia were detected in 57% (n = 102) of the patients. Multivariate logistic regression suggested that CD4+ T cell count < 200 (P = .02; OR 0.2; CI 95% 0.08-0.8) was associated to hyponatremia; similarly, detectable viral load was associated to hypokalemia (P = .02; OR 5.1; CI 95% 1.2-21.3), hypocalcemia (P = .01; OR 4.1; CI 95% 1.3-12.3), and hypermagnesemia (OR 3.9; CI 95% 1.1-13.6). Patient age was associated to both hypophosphatemia (P = .01; OR 2.4; CI 95% 1.1-5.0) and hypermagnesemia (P = .01; OR 2.8; IC 95% 1.1-7.0), and high creatinine levels were associated to nucleoside reverse transcriptase inhibitor treatment (P = .001; OR 42.5; CI 95% 2.2-806.9). Lastly, high BUN levels were associated to age (P = .03; OR 3.8; CI 95% 1.0-14.4), while GFR 60 to 89 mL/min/1.73 m2 was associated to dyslipidemia (P = .02; OR 2.2; CI 95% 1.1-4.5).CD4+ T cell and viral load were the main factors associated with renal biochemical alterations.


Assuntos
Eletrólitos/sangue , Taxa de Filtração Glomerular/fisiologia , Soropositividade para HIV/sangue , Soropositividade para HIV/complicações , Insuficiência Renal Crônica/epidemiologia , Adulto , Idoso , Antirretrovirais/uso terapêutico , Feminino , Soropositividade para HIV/tratamento farmacológico , Humanos , Masculino , México , Pessoa de Meia-Idade , Prevalência , Insuficiência Renal Crônica/diagnóstico , Fatores de Risco , Adulto Jovem
7.
Environ Sci Pollut Res Int ; 28(21): 26269-26279, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33797043

RESUMO

The concept of this paper was to explore the comparative advantage of polymer composite in the formation of a critical part of electrodes, separators, and electrolytes. These parts largely determine the overall performance of new evolving supercapacitors (SC) as against many other existing storage devices. Polymer materials are reputed for their low weight and life-cycle flexibility which makes supercapacitors unique in their functions. In this paper, application and classification of SCs were undertaken to take into consideration the peculiarities of polymer composite suitable for each class of SCs identified in this work. Part of the rationale of this review paper was to bridge the existing gap identified in many storage devices using salient properties inherent in light-weight materials. This paper also discussed the potential threats to SCs, which require further research works. It is expected that this paper would assist other researchers in evolving SCs devoid of low cell voltages, lower energy density, and reduction of production cost.


Assuntos
Carbono , Polímeros , Capacitância Elétrica , Eletrodos , Eletrólitos
8.
J Extra Corpor Technol ; 53(1): 62-67, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33814608

RESUMO

Allogenic blood is a scarce, precious, and expensive resource that is not always available on demand. After termination of cardiopulmonary bypass, a large amount of residual pump blood remains in the extracorporeal circuit. The cell saver washes and concentrates this blood with .9% normal saline (NS), making autologous blood available and reducing the demand for allogenic blood. To quantify the quality of residual pump blood it was washed with either NS or a bicarbonate-buffered solution (Balsol). A qualitative in vitro analysis was conducted. Residual cardiopulmonary bypass blood from forty bypass circuits was processed with a cell saver device, using NS or Balsol solution. Measurements made compared the pH, electrolytes, metabolites, hematocrit, hemoglobin, osmolality, albumin, total protein, and strong ion difference. There were significant differences between the NS and Balsol groups. In the Balsol group, osmolality, electrolytes, and strong ion difference were similar to the constitution of Balsol solution after washing, but not with the normal saline group. Washing residual cardiopulmonary bypass pump blood with Balsol solution results in a resuspended red cell concentrate with a superior electrolyte profile and a strong ion difference similar to that of residual pump blood.


Assuntos
Transfusão de Sangue Autóloga , Ponte Cardiopulmonar , Eletrólitos , Hematócrito , Hemoglobinas/análise
9.
Biosens Bioelectron ; 182: 113144, 2021 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-33799026

RESUMO

We report a dual gate/common channel organic transistor architecture designed for quantifying the concentration of one of the strands of miRNA-21 in solution. The device allows one to measure the differential response between two gate electrodes, viz. one sensing and one reference, both immersed in the electrolyte above the transistor channel. Hybridization with oligonucleotide in the picomolar regime induces a sizable reduction of the current flowing through the transistor channel. The device signal is reported at various gate voltages, showing maximum sensitivity in the sublinear regime, with a limit of detection as low as 35 pM. We describe the dose curves with an analytical function derived from a thermodynamic model of the reaction equilibria relevant in our experiment and device configuration, and we show that the apparent Hill dependence on analyte concentration, whose exponent lies between 0.5 and 1, emerges from the interplay of the different equilibria. The binding free energy characteristic of the hybridization on the device surface is found to be approximately 20% lower with respect to the reaction in solution, hinting to partially inhibiting effect of the surface and presence of competing reactions. Impedance spectroscopy and surface plasmon resonance (SPR) performed on the same oligonucleotide pair were correlated to the electronic current transduced by the EGOFET, and confirmed the selectivity of the biorecognition probe covalently bound on the gold surface.


Assuntos
Técnicas Biossensoriais , MicroRNAs , Eletrodos , Eletrólitos , Transistores Eletrônicos
10.
ACS Sens ; 6(4): 1636-1642, 2021 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-33832225

RESUMO

Here, we describe a new photoelectrochemical imaging method termed light-addressable square wave voltammetry (LASWV). It measures local SWV currents at an unstructured electrolyte/insulator/semiconductor (EIS) field-effect substrate by illuminating and addressing the substrate with an intensity-constant laser. Due to the continuous generation of charge carriers in the light-irradiated semiconductor, the drift and diffusion of photoinjected carriers within the semiconductor bulk would slow down the equilibrium processes of charge and discharge in one potential pulse cycle. Therefore, even though SWV is sampled at the end of the direct and reverse pulses to reject capacitive currents, in our approach, photoinduced capacitive current can still be detected as an effective sensory signal. The obtained current-potential (I-V) curve shows a typical shape corresponding to the accumulation, depletion, and inversion regions of field-effect devices. We demonstrated that LASWV can be used as a field-effect chemical sensor to measure the solution pH and monitor enzymatic reactions. More importantly, since the charge carriers are only generated in the illuminated area, the laser spot in the device can be used as a virtual probe to record local electrochemical properties such as impedance with microresolution.


Assuntos
Técnicas Biossensoriais , Impedância Elétrica , Eletrólitos , Luz , Semicondutores
11.
Biosensors (Basel) ; 11(4)2021 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-33917075

RESUMO

This study aimed to develop simple electrochemical electrodes for the fast detection of chloride, sodium and potassium ions in human serum. A flat thin-film gold electrode was used as the detection electrode for chloride ions; a single-piece type membrane based solid-state ion-selective electrode (ISE), which was formed by covering a flat thin-film gold electrode with a mixture of 7,7,8,8-tetracyanoquinodimethane (TCNQ) and ion-selective membrane (ISM), was developed for sodium and potassium ions detection. Through cyclic voltammetry (CV) and square-wave voltammetry (SWV), the detection data can be obtained within two minutes. The linear detection ranges in the standard samples of chloride, sodium, and potassium ions were 25-200 mM, 50-200 mM, and 2-10 mM, with the average relative standard deviation (RSD) of 0.79%, 1.65%, and 0.47% and the average recovery rates of 101%, 100% and 96%, respectively. Interference experiments with Na+, K+, Cl-, Ca2+, and Mg2+ ions demonstrated that the proposed detection electrodes have good selectivity. Moreover, the proposed detection electrodes have characteristics such as the ability to be prepared under relatively simple process conditions, excellent detection sensitivity, and low RSD, and the detection linear range is suitable for the Cl-, Na+ and K+ concentrations in human serum.


Assuntos
Técnicas Eletroquímicas , Eletrólitos/análise , Eletrodos , Ouro , Humanos , Eletrodos Íon-Seletivos , Íons , Potássio
12.
J Chromatogr A ; 1645: 462091, 2021 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-33845250

RESUMO

In this study, a background electrolyte capable to separate and quantify inorganic cations in high ionic strength samples by UV-absorption indirect detection was designed. In this regard, the four most abundant monovalent and divalent cations in earth crust (K+, Na+, Ca+2, Mg+2) were selected as model compounds. A group of small carboxylic acids and, several toluidines and pyridines were evaluated as mild strength complexing agents and chromophoric probes, respectively. The optimized background electrolyte was composed of 200 mM 2,4,6-trimethylpyridine as the chromophoric probe, 250 mM lactic acid as the weak complexing agent and pH buffering reagent (adjusted to pH 4.5), and 5% v/v methanol as organic solvent modifier. Based on a minimum number of components, it provided outstanding separation performance in less than 4 min in a wide linear dynamic range (10 - 2500 µg·mL-1). Performances were contrasted against a reference method based on conductometric detection. Furthermore, studies of separation efficiency and peak shape were carried out at different analyte concentrations in high electric conductivity solutions. The herein developed method demonstrated exceptional features in terms of limits of detection (~10 µg·mL-1), resolution, speed of analysis, sensitivity and peak capacity in high electric conductivity samples. Moreover, the method was successfully applied to high ionic strength samples such as rock digest, sea water, soy sauce and isotonic drinks.


Assuntos
Cátions/análise , Eletrólitos/química , Eletroforese Capilar/métodos , Espectrofotometria Ultravioleta/métodos , Ácido Láctico/química , Limite de Detecção , Metanol/química , Concentração Osmolar , Piridinas/química
13.
Biosensors (Basel) ; 11(3)2021 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-33809382

RESUMO

Immunostaining has been widely used in cancer prognosis for the quantitative detection of cancer cells present in the bloodstream. However, conventional detection methods based on the target membrane protein expression exhibit the risk of missing cancer cells owing to variable protein expressions. In this study, the resistive pulse method (RPM) was employed to discriminate between cultured cancer cells (NCI-H1650) and T lymphoblastoid leukemia cells (CCRF-CEM) by measuring the ionic current response of cells flowing through a micro-space. The height and shape of a pulse signal were used for the simultaneous measurement of size, deformability, and surface charge of individual cells. An accurate discrimination of cancer cells could not be obtained using 1.0 × phosphate-buffered saline (PBS) as an electrolyte solution to compare the size measurements by a microscopic observation. However, an accurate discrimination of cancer cells with a discrimination error rate of 4.5 ± 0.5% was achieved using 0.5 × PBS containing 2.77% glucose as the electrolyte solution. The potential application of RPM for the accurate discrimination of cancer cells from leukocytes was demonstrated through the measurement of the individual cell size, deformability, and surface charge in a solution with a low electrolyte concentration.


Assuntos
Eletrólitos/análise , Proteínas de Membrana/análise , Técnicas Biossensoriais , Linhagem Celular Tumoral , Humanos , Neoplasias/diagnóstico
14.
Int J Mol Sci ; 22(4)2021 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-33671243

RESUMO

Brown alga Ectocarpus sp. belongs to Phaeophyceae, a class of macroalgae that evolved complex multicellularity. Ectocarpus sp. is a dominant seaweed in temperate regions, abundant mostly in the intertidal zones, an environment with high levels of abiotic stresses. Previous transcriptomic analysis of Ectocarpus sp. revealed several genes consistently induced by various abiotic stresses; one of these genes is Esi0017_0056, which encodes a protein with unknown function. Bioinformatics analyses indicated that the protein encoded by Esi0017_0056 is soluble and monomeric. The protein was successfully expressed in Escherichia coli,Arabidopsis thaliana and Nicotiana benthamiana. In A. thaliana the gene was expressed under constitutive and stress inducible promoters which led to improved tolerance to high salinity and temperature stresses. The expression of several key abiotic stress-related genes was studied in transgenic and wild type A. thaliana by qPCR. Expression analysis revealed that genes involved in ABA-induced abiotic stress tolerance, K+ homeostasis, and chaperon activities were significantly up-regulated in the transgenic line. This study is the first report in which an unknown function Ectocarpus sp. gene, highly responsive to abiotic stresses, was successfully expressed in A. thaliana, leading to improved tolerance to salt and temperature stress.


Assuntos
Adaptação Fisiológica , Proteínas de Algas/metabolismo , Arabidopsis/genética , Arabidopsis/fisiologia , Temperatura Alta , Feófitas/metabolismo , Salinidade , Estresse Fisiológico , Adaptação Fisiológica/genética , Proteínas de Algas/química , Proteínas de Algas/genética , Arabidopsis/crescimento & desenvolvimento , Eletrólitos/metabolismo , Escherichia coli/metabolismo , Regulação da Expressão Gênica de Plantas , Filogenia , Plantas Geneticamente Modificadas , Regiões Promotoras Genéticas/genética , Plântula/genética , Estresse Fisiológico/genética , Tabaco/metabolismo
15.
Molecules ; 26(4)2021 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-33668491

RESUMO

In this study, a complex consisting of 2-hydroxypropyl-ß-cyclodextrin and 5,10,15,20-tetrakis (4-hydroxyphenyl) porphyrin, (named dual chiral-achiral selector complex) was used for the determination of two novel potential anticancer agents of (I) and (II) aminoalkanol derivatives. This work aimed at developing an effective method that can be utilized for the determination of I (S), I (R), and II (S) and II (R) enantiomers of (I) and (II) compounds through the use of a dual chiral-achiral selector complex consisting of hydroxypropyl-ß-cyclodextrin and 5,10,15,20-tetrakis (4-hydroxyphenyl) porphyrin system by applying capillary electrophoresis. This combination proved to be beneficial in achieving high separation selectivity due to the combined effects of different modes of chiral discrimination. The enantiomers of (I) and (II) compounds were separated within a very short time of 3.6-7.2 min, in pH 2.5 phosphate buffer containing 2-hydroxypropyl-ß-cyclodextrin and 5,10,15,20-tetrakis (4-hydroxyphenyl) porphyrin system at a concentration of 5 and 10 mM, respectively, at 25 °C and +10 kV. The detection wavelength of the detector was set at 200 nm. The LOD for I (S), I (R), II (S), and II (R) was 65.2, 65.6, 65.1, and 65.7 ng/mL, respectively. LOQ for I (S), I (R), II (S), and II (R) was 216.5, 217.8, 217.1, and 218.1 ng/mL, respectively. Recovery was 94.9-99.9%. The repeatability and reproducibility of the method based on the values of the migration time, and the area under the peak was 0.3-2.9% RSD. The stability of the method was determined at 0.1-4.9% RSD. The developed method was used in the pilot studies for determining the enantiomers I (S), I (R), II (S), and II (R) in the blood serum.


Assuntos
2-Hidroxipropil-beta-Ciclodextrina/química , Aminas/isolamento & purificação , Aminas/farmacologia , Antineoplásicos/farmacologia , Eletroforese Capilar , Porfirinas/química , Antineoplásicos/sangue , Tampões (Química) , Eletrólitos/química , Concentração de Íons de Hidrogênio , Limite de Detecção , Porfirinas/farmacologia , Análise de Regressão , Reprodutibilidade dos Testes , Estereoisomerismo , Temperatura
16.
J Vis Exp ; (168)2021 02 10.
Artigo em Inglês | MEDLINE | ID: mdl-33645554

RESUMO

Scanning electrochemical microscopy (SECM) is used to measure the local electrochemical behavior of liquid/solid, liquid/gas and liquid/liquid interfaces. Atomic force microscopy (AFM) is a versatile tool to characterize micro- and nanostructure in terms of topography and mechanical properties. However, conventional SECM or AFM provides limited laterally resolved information on electrical or electrochemical properties at nanoscale. For instance, the activity of a nanomaterial surface at crystal facet levels is difficult to resolve by conventional electrochemistry methods. This paper reports the application of a combination of AFM and SECM, namely, AFM-SECM, to probe nanoscale surface electrochemical activity while acquiring high-resolution topographical data. Such measurements are critical to understanding the relationship between nanostructure and reaction activity, which is relevant to a wide range of applications in material science, life science and chemical processes. The versatility of the combined AFM-SECM is demonstrated by mapping topographical and electrochemical properties of faceted nanoparticles (NPs) and nanobubbles (NBs), respectively. Compared to previously reported SECM imaging of nanostructures, this AFM-SECM enables quantitative assessment of local surface activity or reactivity with higher resolution of surface mapping.


Assuntos
Eletroquímica/métodos , Microscopia de Força Atômica , Microscopia Eletroquímica de Varredura , Nanoestruturas/ultraestrutura , Cobre/química , Eletrólitos/química , Nanopartículas/química , Nanopartículas/ultraestrutura , Nanoestruturas/química , Oxirredução , Silício/química , Software
18.
J Vis Exp ; (169)2021 03 04.
Artigo em Inglês | MEDLINE | ID: mdl-33749669

RESUMO

Starch from all plant sources are made up of granules in a range of sizes and shapes having different occurrence frequencies, i.e., exhibiting a size and a shape distribution. Starch granule size data determined using several types of particle sizing techniques are often problematic due to poor reproducibility or lack of statistical significance resulting from some insurmountable systematic errors, including sensitivity to granule shapes and limits of granule-sample sizes. We outlined a procedure for reproducible and statistically valid determinations of starch granule size distributions using the electrical sensing zone technique, and for specifying the determined granule lognormal size distributions using an adopted two-parameter multiplicative form with improved accuracy and comparability. It is applicable to all granule sizing analyses of gram-scale starch samples, and, therefore, could facilitate studies on how starch granule sizes are molded by the starch biosynthesis apparatus and mechanisms; and how they impact properties and functionality of starches for food and industrial uses. Representative results are presented from replicate analyses of granule size distributions of sweetpotato starch samples using the outlined procedure. We further discussed several key technical aspects of the procedure, especially, the multiplicative specification of granule lognormal size distributions and some technical means for overcoming frequent aperture blockage by granule aggregates.


Assuntos
Tamanho da Partícula , Amido/química , Eletrólitos/química , Ipomoea batatas/química , Reprodutibilidade dos Testes
19.
Proc Natl Acad Sci U S A ; 118(6)2021 02 09.
Artigo em Inglês | MEDLINE | ID: mdl-33526661

RESUMO

The choroid plexus (CP) is an extensively vascularized neuroepithelial tissue that projects into the brain ventricles. The restriction of transepithelial transport across the CP establishes the blood-cerebrospinal fluid (CSF) barrier that is fundamental to the homeostatic regulation of the central nervous system microenvironment. However, the molecular mechanisms that control this process remain elusive. Here we show that the genetic ablation of Sox9 in the hindbrain CP results in a hyperpermeable blood-CSF barrier that ultimately upsets the CSF electrolyte balance and alters CSF protein composition. Mechanistically, SOX9 is required for the transcriptional up-regulation of Col9a3 in the CP epithelium. The reduction of Col9a3 expression dramatically recapitulates the blood-CSF barrier defects of Sox9 mutants. Loss of collagen IX severely disrupts the structural integrity of the epithelial basement membrane in the CP, leading to progressive loss of extracellular matrix components. Consequently, this perturbs the polarized microtubule dynamics required for correct orientation of apicobasal polarity and thereby impedes tight junction assembly in the CP epithelium. Our findings reveal a pivotal cascade of SOX9-dependent molecular events that is critical for construction of the blood-CSF barrier.


Assuntos
Sangue/metabolismo , Polaridade Celular , Líquido Cefalorraquidiano/metabolismo , Plexo Corióideo/metabolismo , Colágeno Tipo IX/metabolismo , Células Epiteliais/citologia , Fatores de Transcrição SOX9/metabolismo , Animais , Membrana Basal/metabolismo , Colágeno Tipo IX/genética , Eletrólitos/líquido cefalorraquidiano , Células Epiteliais/metabolismo , Epitélio/metabolismo , Matriz Extracelular/metabolismo , Deleção de Genes , Técnicas de Silenciamento de Genes , Camundongos Knockout , Microtúbulos/metabolismo , Junções Íntimas/metabolismo , Transcrição Genética
20.
Lab Chip ; 21(5): 795-820, 2021 03 07.
Artigo em Inglês | MEDLINE | ID: mdl-33565540

RESUMO

Recently, organic bioelectronics has attracted considerable interest in the scientific community. The impressive growth that it has undergone in the last 10 years has allowed the rise of the completely new field of cellular organic bioelectronics, which has now the chance to compete with consolidated approaches based on devices such as micro-electrode arrays and ISFET-based transducers both in in vitro and in vivo experimental practice. This review focuses on cellular interfaces based on organic active devices and has the intent of highlighting the recent advances and the most innovative approaches to the ongoing and everlasting challenge of interfacing living matter to the "external world" in order to unveil the hidden mechanisms governing its behavior. Device-wise, three different organic structures will be considered in this work, namely the organic electrochemical transistor (OECT), the solution-gated organic transistor (SGOFET - which is presented here in two possible different versions according to the employed active material, namely: the electrolyte-gated organic transistor - EGOFET, and the solution gated graphene transistor - gSGFET), and the organic charge modulated field effect transistor (OCMFET). Application-wise, this work will mainly focus on cellular-based biosensors employed in in vitro and in vivo cellular interfaces, with the aim of offering the reader a comprehensive retrospective of the recent past, an overview of the latest innovations, and a glance at the future prospects of this challenging, yet exciting and still mostly unexplored scientific field.


Assuntos
Técnicas Biossensoriais , Grafite , Eletrodos , Eletrólitos , Estudos Retrospectivos , Transistores Eletrônicos
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