RESUMO
An analytical method based on capillary electrophoresis (CE) using capacitively coupled contactless conductivity detection (C4 D) was developed and validated for fast, straightforward, and reliable determination of lactate in artificial and human sweat samples. The background electrolyte was composed of equimolar concentrations (10 mmol/L) of 2-(N-morpholino)ethanesulfonic acid and histidine, with 0.2 mmol/L of cetyltrimethylammonium bromide as electroosmotic flow inverter. The limit of detection and quantification were 3.1 and 10.3 µmol/L, respectively. Recoveries in the 97 to 118% range were obtained using sweat samples spiked with lactate at three concentration levels, indicating an acceptable accuracy. The intraday and interday precisions were 1.49 and 7.08%, respectively. The proposed CE-C4 D method can be a starting point for monitoring lactate concentrations in sweat samples for diagnostics, physiological studies, and sports performance assessment applications.
Assuntos
Ácidos Alcanossulfônicos , Ácido Láctico , Morfolinas , Suor , Humanos , Cetrimônio , Eletroforese Capilar/métodos , Condutividade ElétricaRESUMO
Urinary tract infections (UTIs) are a significant cause of morbidity in healthcare systems and are prominently associated with applying urethral catheters, particularly in surgeries. Polyvinyl chloride (PVC) is extensively utilized in the fabrication of catheters. Biofilms, complex polymeric constructions, provide a protective milieu for cell multiplication and the enhancement of antibiotic resistance. Strategies to counteract biofilm development on medical apparatuses' surfaces incorporate antimicrobial agents such as N,N-dodecyl, and methyl polyethylenimine (DMPEI). This research endeavored to characterize the morphology of PVC and PVC-DMPEI surfaces utilizing Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) and to gauge hydrophobicity through contact angle measurements. Employing Escherichia coli, Staphylococcus aureus, and Candida albicans in adhesion assays enabled the assessment of DMPEI's efficacy in preventing microbial adherence to PVC. Butanol successfully solubilized 2 mg.mL-1 DMPEI without altering the PVC structure. SEM results substantiated the formation of a DMPEI layer on the PVC surface, which led to decreased surface roughness, as validated by AFM, and increased hydrophilicity, as demonstrated by contact angle evaluations. E. coli, S. aureus, and C. albicans exhibited significant adhesion reduction, 89.3%, 94.3%, and 86.6% on PVC-DMPEI surfaces. SEM visualizations confirmed reduced cellular colonization on PVC-DMPEI and highlighted considerable morphological modifications in E. coli. Consequently, DMPEI films effectively minimize the adhesion of E. coli, S. aureus, and C. albicans on PVC surfaces. DMPEI, with its potential as a protective coating for innovative medical devices, promises to inhibit biofilm adherence effectively.
Assuntos
Escherichia coli , Polietilenoimina , Polietilenoimina/farmacologia , Staphylococcus aureus , Catéteres , Biofilmes , Candida albicansRESUMO
In this work, we demonstrate for the first time the design and fabrication of microchip electrophoresis devices containing cross-shaped channels and spiral electrodes around the separation channel for microchip electrophoresis and capacitively coupled contactless conductivity detection. The whole device was prepared in a digital light processing-based 3D printer in poly(ethylene glycol) diacrylate resin. Outstanding X-Y resolution of the customized 3D printer ensured the fabrication of 40-µm cross section channels. The spiral channels were filled with melted gallium to form conductive electrodes around the separation channel. We demonstrate the applicability of the device on the separation of sodium, potassium, and lithium cations by microchip electrophoresis. Graphical abstract.
RESUMO
Arginine (ARG), ascorbic acid (ASC) and aspartic acid (ASP) are very popular and widely consumed active ingredients used for fatigue treatment or improvement of physical performance. For this reason, these compounds are usually available in the same pharmaceutical formulation. In the current paper, we describe for the first-time methods for simultaneous determination of ARG, ASC and ASP using capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C4D) and with UV spectrophotometric detection (CE-UV). The proposed methods are simple, rapid (78 and 23 injections h-1, respectively) and have low environmental impact (minimal waste generation). The separation by CE-C4D was achieved with a background electrolyte (BGE) composed by 20â¯mmolâ¯L-1 N-tris(hydroxymethyl)- methyl]-3-aminopropanesulfonic acid (TAPS) and 10â¯mmolâ¯L-1 of NaOH (pH 8.7). The limits of detection (LOD) were 0.01, 0.02 and 0.04â¯mmolâ¯L-1 for ARG, ASC and ASP, respectively. The proposed CE-UV method was optimized with a BGE composed by 10â¯mmolâ¯L-1 sodium tetraborate (pH 9.4). The limits of detection (LOD) were 0.03, 0.02 and 0.04â¯mmolâ¯L-1 for ARG, ASC and ASP, respectively. No statistically significant differences were observed (95% confidence level) between the results obtained by the developed CE methods and reference procedures (HPLC for ARG, iodometry for ASC and, acid-base titration for ASP).
RESUMO
This study reports the separation of fructose, galactose, glucose, lactose and sucrose on glass microchip electrophoresis (ME) devices using a microfluidic platform adapted with external reservoirs for controlling the electrolysis phenomenon. The connections between external reservoirs and microfluidic platform were performed by saline bridges created using silicone tubing filled with BGE. The separation conditions were optimized and the best results were achieved using a BGE containing 75 mmol/L NaOH and 15 mmol/L trisodium phosphate. Electrophoretic separations were monitored using a capacitively coupled contactless conductivity detection system. The controlled electrolysis has successfully allowed the application of a higher voltage on the separation channel promoting the baseline separation of five carbohydrates within 180 s with great run-to-run repeatability (RSD < 1%). The achieved efficiencies ranged from 45 000 ± 6000 to 70 000 ± 3000 plates/m demonstrating a performance better than ME devices without controlled electrolysis. The proposed system offered good linearity from 1 to 10 mmol/L and LODs between 150 and 740 µmol/L. The use of external tubes for controlling the electrolysis phenomenon on ME devices has solved common problems associated to run-to-run repeatability and analytical reliability required for routine and quantitative analysis.
Assuntos
Eletroforese em Microchip/métodos , Açúcares/análise , Açúcares/isolamento & purificação , Condutividade Elétrica , Concentração de Íons de Hidrogênio , Limite de Detecção , Modelos Lineares , Reprodutibilidade dos Testes , Açúcares/químicaRESUMO
We present an on-line, single step coupling between liquid-liquid extraction and capillary electrophoresis with capacitively coupled contactless conductivity detection, which allows an efficient analysis of complex food matrices with high sodium content. The sodium depletion was demonstrated using an aqueous two-phase system. The aqueous two-phase system enables the electrically driven extraction of the target compounds. The sample was prepared in Dextran-rich phase (8% w/v 500 kDa Dextran, DEX). The background electrolyte (acetic acid 5.0 mol/L) contained 6% w/v of 6 kDa PEG. As proof of applicability, we employed the developed method for glutamic acid quantification on soy sauces. The peak area of glutamic acid presents no significant difference (α = 0.05), while the peak area of the sodium presented a reduction of 11.7 ± 0.2 and 19 ± 3% for premium and low-cost soy sauce samples analyzed. The glutamic acid concentration for premium soy sauce sample was 2.7 ± 0.8 and 4.8 ± 0.4 g/L, and for low-cost soy sauce sample, the concentration was 9.9 ± 0.9 g/L, which agreed with those obtained by other analytical techniques.
Assuntos
Eletroforese Capilar/métodos , Ácido Glutâmico/análise , Alimentos de Soja/análise , Dextranos , Condutividade Elétrica , Ácido Glutâmico/química , Ácido Glutâmico/isolamento & purificaçãoRESUMO
Dielectrophoresis (DEP) is the electrokinetic movement of non-charged particles when they are subjected to a non-uniform electric field. This is a growing area of research, which can be used for trapping, concentrating and separating different particles. Some work has been reported with the intention of trapping metal particles to optimize the surface enhanced Raman spectroscopy (SERS) effect. In this paper, we use DEP with insulating structures (iDEP) to generate a non-uniform electric field for trapping gold nanoparticles (AuNP). The system was coupled to a Raman spectrometer for the detection of Crystal Violet by utilizing the SERS effect.
RESUMO
In-channel amperometric detection combined with dual-channel microchip electrophoresis is evaluated using a two-electrode isolated potentiostat for reverse polarity separations. The device consists of two separate channels with the working and reference electrodes placed at identical positions relative to the end of the channel, enabling noise subtraction. In previous reports of this configuration, normal polarity and a three-electrode detection system were used. In the two-electrode detection system described here, the electrode in the reference channel acts as both the counter and reference. The effect of electrode placement in the channels on noise and detector response was investigated using nitrite, tyrosine, and hydrogen peroxide as model compounds. The effects of electrode material and size and type of reference electrode on noise and the potential shift of hydrodynamic voltammograms for the model compounds were determined. In addition, the performance of two- and three-electrode configurations using Pt and Ag/AgCl reference electrodes was compared. Although the signal was attenuated with the Pt reference, the noise was also significantly reduced. It was found that lower LOD were obtained for all three compounds with the dual-channel configuration compared to single-channel, in-channel detection. The dual-channel method was then used for the detection of nitrite in a dermal microdialysis sample obtained from a sheep following nitroglycerin administration.
Assuntos
Técnicas Eletroquímicas/instrumentação , Eletroforese em Microchip/instrumentação , Técnicas Eletroquímicas/métodos , Eletrodos , Eletroforese em Microchip/métodos , Desenho de Equipamento , Limite de Detecção , Microdiálise , NitritosRESUMO
Electrospun materials have been widely explored for biomedical applications because of their advantageous characteristics, i.e., tridimensional nanofibrous structure with high surface-to-volume ratio, high porosity, and pore interconnectivity. Furthermore, considering the similarities between the nanofiber networks and the extracellular matrix (ECM), as well as the accepted role of changes in ECM for hernia repair, electrospun polymer fiber assemblies have emerged as potential materials for incisional hernia repair. In this work, we describe the application of electrospun non-absorbable mats based on poly(ethylene terephthalate) (PET) in the repair of abdominal defects, comparing the performance of these meshes with that of a commercial polypropylene mesh and a multifilament PET mesh. PET and PET/chitosan electrospun meshes revealed good performance during incisional hernia surgery, post-operative period, and no evidence of intestinal adhesion was found. The electrospun meshes were flexible with high suture retention, showing tensile strengths of 3 MPa and breaking strains of 8-33%. Nevertheless, a significant foreign body reaction (FBR) was observed in animals treated with the nanofibrous materials. Animals implanted with PET and PET/chitosan electrospun meshes (fiber diameter of 0.71 ± 0.28 µm and 3.01 ± 0.72 µm, respectively) showed, respectively, foreign body granuloma formation, averaging 4.2-fold and 7.4-fold greater than the control commercial mesh group (Marlex). Many foreign body giant cells (FBGC) involving nanofiber pieces were also found in the PET and PET/chitosan groups (11.9 and 19.3 times more FBGC than control, respectively). In contrast, no important FBR was observed for PET microfibers (fiber diameter = 18.9 ± 0.21 µm). Therefore, we suggest that the reduced dimension and the high surface-to-volume ratio of the electrospun fibers caused the FBR reaction, pointing out the need for further studies to elucidate the mechanisms underlying interactions between cells/tissues and nanofibrous materials in order to gain a better understanding of the implantation risks associated with nanostructured biomaterials.
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Materiais Biocompatíveis/farmacologia , Quitosana/farmacologia , Reação a Corpo Estranho/induzido quimicamente , Granuloma de Corpo Estranho/induzido quimicamente , Nanofibras/química , Polietilenoglicóis/farmacologia , Telas Cirúrgicas/veterinária , Animais , Materiais Biocompatíveis/química , Quitosana/química , Modelos Animais de Doenças , Técnicas Eletroquímicas , Reação a Corpo Estranho/patologia , Granuloma de Corpo Estranho/patologia , Hérnia Abdominal/cirurgia , Herniorrafia/instrumentação , Masculino , Teste de Materiais , Polietilenoglicóis/química , Polietilenotereftalatos , Polipropilenos/farmacologia , Ratos , Ratos Wistar , Propriedades de Superfície , Suturas , Resistência à TraçãoRESUMO
Twenty-three naphthoimidazoles and six naphthoxazoles were synthesised and evaluated against susceptible and rifampicin- and isoniazid-resistant strains of Mycobacterium tuberculosis. Among all the compounds evaluated, fourteen presented MIC values in the range of 0.78 to 6.25 µg/mL against susceptible and resistant strains of M. tuberculosis. Five structures were solved by X-ray crystallographic analysis. These substances are promising antimycobacterial prototypes.