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1.
Nat Commun ; 11(1): 3840, 2020 07 31.
Artigo em Inglês | MEDLINE | ID: mdl-32737293

RESUMO

Currently, human magnetic resonance (MR) examinations are becoming highly specialized with a pre-defined and often relatively small target in the body. Conventionally, clinical MR equipment is designed to be universal that compromises its efficiency for small targets. Here, we present a concept for targeted clinical magnetic resonance imaging (MRI), which can be directly integrated into the existing clinical MR systems, and demonstrate its feasibility for breast imaging. The concept comprises spatial redistribution and passive focusing of the radiofrequency magnetic flux with the aid of an artificial resonator to maximize the efficiency of a conventional MR system for the area of interest. The approach offers the prospect of a targeted MRI and brings novel opportunities for high quality specialized MR examinations within any existing MR system.


Assuntos
Neoplasias da Mama/diagnóstico por imagem , Cerâmica/efeitos da radiação , Espectroscopia Dielétrica/métodos , Imagem por Ressonância Magnética/métodos , Espectroscopia de Ressonância Magnética/métodos , Adulto , Cerâmica/química , Espectroscopia Dielétrica/instrumentação , Radiação Eletromagnética , Desenho de Equipamento , Feminino , Voluntários Saudáveis , Humanos , Imagem por Ressonância Magnética/instrumentação , Imagens de Fantasmas , Razão Sinal-Ruído
2.
Food Chem ; 333: 127532, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32668396

RESUMO

Poly(melamine) (PMel) was synthesized via the electropolymerization of melamine monomer, which was then characterized by field-emission scanning electron microscopy (FESEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The possible polymerization mechanisms of melamine were also revealed by FT-IR spectroscopy and UV-Vis spectroscopy. Next, the PMel modified GCE (PMel/GCE) was used for the simultaneous determination of nitrite (NO2-) and tartrazine, and the parameters were optimized. The kinetic study showed that the electrochemical oxidation of nitrite and tartrazine at the surface of PMel/GCE is a typical surface-controlled electrode process. Under the optimun conditions, the developed sensor outperformed those previously reported, and it also exhibited high selectivity and reproducibility. Finally, the PMel/GCE was used for the simultaneous determination of nitrite and tartrazine in foodstuffs, and the results indicated that the proposed sensor could be a promising candidate for accurate determination of nitrite and tartrazine in real food samples.


Assuntos
Nitritos/análise , Polimerização , Tartrazina/análise , Triazinas/química , Espectroscopia Dielétrica , Eletroquímica , Eletrodos , Microscopia Eletrônica de Varredura , Nitritos/química , Oxirredução , Reprodutibilidade dos Testes , Tartrazina/química , Fatores de Tempo
3.
PLoS One ; 15(7): e0235640, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32730268

RESUMO

BACKGROUND: Fluid overload is common in patients with diabetes and chronic kidney disease (DM and CKD; DMCKD) and can lead to structural and functional cardiac abnormalities including left ventricular hypertrophy (LVH) and left ventricular diastolic dysfunction (LVDD). Fluid overload represents a crucial step in the pathophysiological pathways to chronic heart failure in patients with end-stage renal disease. We evaluated the impact of fluid overload on cardiac alterations in patients with diabetes and non-dialysis-dependent CKD stage 5 (DMCKD5-ND) without intrinsic heart disease. METHODS: Bioimpedance spectroscopy, echocardiography, and N-terminal prohormone of B-type natriuretic peptide (NT-proBNP) measurement were performed in 135 consecutive patients on the same day. Patients were divided into groups by tertiles of overhydration/extracellular water (OH/ECW) per bioimpedance spectroscopy. RESULTS: Fluid balance markers including OH/ECW and NT-proBNP were significantly higher in the LVDD+LVH group. OH/ECW and its exacerbation were positively associated with the ratio between early mitral inflow and annular early diastolic velocities (E/e' ratio) and left ventricular mass index (LVMI). The prevalence of LVH progressively increased across increasing tertiles of OH/ECW. In multiple regression analyses, OH/ECW as a continuous and categorical variable was independently associated with the E/e' ratio and LVMI after adjustment for multiple confounding factors. CONCLUSIONS: Fluid overload was independently associated with LVDD and LVH in patients with DMCKD5-ND. Our study suggests that structural and functional cardiac abnormalities and volume status should be evaluated simultaneously in patients with early-stage DMCKD rather than only DMCKD5-ND, in addition to intensive blood pressure and glycemic control, regardless of evident cardiovascular disease.


Assuntos
Diabetes Mellitus Tipo 2/patologia , Hidratação , Falência Renal Crônica/patologia , Idoso , Espectroscopia Dielétrica , Ecocardiografia , Feminino , Taxa de Filtração Glomerular , Humanos , Hipertrofia Ventricular Esquerda/epidemiologia , Hipertrofia Ventricular Esquerda/patologia , Falência Renal Crônica/terapia , Modelos Lineares , Masculino , Pessoa de Meia-Idade , Peptídeo Natriurético Encefálico/sangue , Fragmentos de Peptídeos/sangue , Prevalência , Diálise Renal , Índice de Gravidade de Doença , Disfunção Ventricular Esquerda/patologia
4.
J Pharmacol Sci ; 143(4): 320-324, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32505645

RESUMO

Cellular dielectric spectroscopy (CDS) is a novel technology enabling pharmacological evaluation of multiple receptor types with a label-free cell-based assay. We evaluated activities of a family of ligand-gated channels, transient receptor potential vanilloid 1 (TRPV1) and transient receptor potential ankyrin 1 (TRPA1) channels by an electrical impedance-based biosensor (CellKey™ system) using CDS. Measures of both potency (EC50) and efficacy (Emax) of these agonists with CellKey™ were almost identical to those made using the traditional Ca2+ influx assay in TRPV1- or TRPA1-expressing cells, suggesting that CellKey™ is a simpler and easier means of evaluating TRP activities.


Assuntos
Espectroscopia Dielétrica/métodos , Canais de Receptores Transientes de Potencial/metabolismo , Células HEK293 , Humanos , Canal de Cátion TRPA1 , Canais de Cátion TRPV
5.
Phys Ther ; 100(8): 1384-1392, 2020 08 12.
Artigo em Inglês | MEDLINE | ID: mdl-32379872

RESUMO

OBJECTIVE: Following breast cancer surgery with lymph node removal, women are at risk of developing lymphedema in the upper extremity or trunk. Currently, trunk lymphedema diagnosis relies on a clinical assessment because no quantifiable standard method exists. Tissue dielectric constant (TDC) values are quantifiable measures of localized skin tissue water and may be able to detect trunk lymphedema. The goal of this study was to (1) compare parameters derived from TDC measurements with those derived from clinically accepted criteria for trunk lymphedema in women following breast cancer surgery and (2) explore the potential utility of TDC to detect trunk lymphedema early in its progression. METHODS: This prospective longitudinal study, a secondary analysis from a larger study, observed women with and without clinically determined truncal lymphedema following breast cancer surgery. TDC was measured on the lateral trunk wall at post-surgery weeks 2, 4, 12, and 78 in women who had surgical breast cancer treatment with lymph node removal. Clinical assessment for trunk lymphedema was determined at 78 weeks by a lymphedema expert. Comparison of TDC measurements in women with and without clinical trunk lymphedema was analyzed. RESULTS: Clinical assessment identified trunk lymphedema in 15 out of 32 women at 78 weeks. These women had TDC ratios statistically higher than women without truncal lymphedema. CONCLUSION: The overall findings indicate that TDC has the ability to quantify trunk lymphedema and might be valuable in early detection. IMPACT: TDC may be a beneficial tool in the early detection of breast cancer-related trunk lymphedema, which could trigger intervention. LAY SUMMARY: A new device may help recognize trunk lymphedema in patients with breast cancer so they could receive appropriate treatment.


Assuntos
Água Corporal , Linfedema Relacionado a Câncer de Mama/diagnóstico , Neoplasias da Mama/cirurgia , Campos Eletromagnéticos , Excisão de Linfonodo , Linfedema Relacionado a Câncer de Mama/etiologia , Linfedema Relacionado a Câncer de Mama/fisiopatologia , Espectroscopia Dielétrica/métodos , Feminino , Humanos , Estudos Longitudinais , Linfa , Estudos Prospectivos , Parede Torácica , Fatores de Tempo
6.
Int J Nanomedicine ; 15: 2219-2230, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32280216

RESUMO

Purpose: In the present study, a highly sensitive and simple electrochemical (EC) aptasensor for the detection of serpin A12 as a novel biomarker of diabetes was developed on a platform where flower-like gold microstructures (FLGMs) are electrodeposited onto a disposable screen-printed carbon electrode. Meanwhile, serpin A12-specific thiolated aptamer was covalently immobilized on the FLGMs. Methods: The electrochemical activity of a fabricated aptasensor under various conditions were examined by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Aptamer concentration, deposition time, self-assembly time, and incubation time were optimized for assay of serpin A12. The differential pulse voltammetry (DPV) was implemented for quantitative detection of serpin A12 in K3 [Fe (CN) 6]/K4 [Fe (CN) 6] solution (redox probe). Results: The label-free aptasensor revealed a linear range of serpin A12 concentration (0.039-10 ng/mL), detection limit of 0.020 ng/mL (S/N=3), and 0.031 ng/mL in solution buffer and plasma, respectively. Conclusion: The results indicate that this aptasensor has a high sensitivity, selectivity, stability, and acceptable reproducibility for detection of serpin A12 in diabetic patients.


Assuntos
Aptâmeros de Nucleotídeos/química , Diabetes Mellitus Tipo 2/sangue , Técnicas Eletroquímicas/instrumentação , Eletrodos , Serpinas/sangue , Animais , Biomarcadores/sangue , Técnicas Biossensoriais/instrumentação , Técnicas Biossensoriais/métodos , Carbono/química , Diabetes Mellitus Experimental/sangue , Espectroscopia Dielétrica/métodos , Técnicas Eletroquímicas/métodos , Galvanoplastia , Desenho de Equipamento , Ouro/química , Limite de Detecção , Masculino , Ratos Wistar , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
7.
Food Chem ; 321: 126682, 2020 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-32278274

RESUMO

An inexpensive and environmental friendly electrochemical sensor based on a glassy carbon electrode (GC) modified with graphene quantum dots (GQDs) and Nafion (NF) has been developed for the determination of Cd(II) and Pb(II) in bivalve mollusks using square wave anodic stripping voltammetry (SWASV). GQDs were characterized by UV-Vis spectroscopy, fluorescence and transmission electronic microscopy (TEM). The modified electrode was evaluated by cyclic voltammetry, scanning electronic microscopy (SEM) and electrochemical impedance spectroscopy (EIS). A linearity of 20-200 µg L-1 was found, with a limit of detection (LOD) of 11.30 µg L-1 for Cd(II) and 8.49 µg L-1 for Pb(II). The proposed methodology was validated with a certified reference material TMDA-64.2. The reproducibility of GC/GQDs-NF for both species had an RSD of less than 10%. The results were compared with ICP-OES. The method was applied in the determination of Cd(II) and Pb(II) in bivalve mollusks samples with excellent results.


Assuntos
Bivalves/química , Cádmio/análise , Chumbo/análise , Animais , Carbono/química , Espectroscopia Dielétrica , Técnicas Eletroquímicas/métodos , Eletrodos , Grafite/química , Limite de Detecção , Pontos Quânticos , Reprodutibilidade dos Testes
8.
Adv Biochem Eng Biotechnol ; 174: 17-41, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32328684

RESUMO

Aptamers are a specific class of ligands with high affinities comparable to antibodies, which are selected and synthesized in vitro. In combination with impedance spectroscopy as sensitive measurement method, we gain a class of biosensors with high potential for handheld devices and point-of-care tests. In this review, we report on recent advances in aptamer-based impedimetric biosensors. Besides giving a short summary of electrochemical measurement techniques, the most exciting innovative developments of detection strategies in the last decades are reviewed. Finally, important criteria for the comparison of aptamer-based biosensors are discussed.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Técnicas Biossensoriais/instrumentação , Técnicas Biossensoriais/tendências , Espectroscopia Dielétrica , Técnicas Eletroquímicas/tendências
9.
Food Chem ; 315: 126289, 2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-32014670

RESUMO

Trace residue of mycotoxins in complex medicinal and edible food matrices has brought huge challenges for the development of ultrasensitive analytical methods. Here, a green electrochemical immunosensor for the ultrasensitive detection of ochratoxin A (OTA) was fabricated by self-assembling a compact 2-mercaptoacetic (TGA) monolayer on the surface of the working Au electrode to form the Au/TGA/bovine serum aibumin (BSA)-OTA/anti-OTA monoclonal antibody composite probes for selective and ultra-sensitive detection of OTA based on indirect competitive principle and differential pulse voltammetry analysis. The electrochemical impedance spectroscopy and cyclic voltammetry methods were introduced to characterize the assemble situation of the TGA-modified Au electrode and optimize some critical parameters for the green electrochemical immunoseonsor. Under the optimal conditions, the developed immunosensor exhibited much lower limit of detection (0.08 ng/mL) in the range of 0.1-1.0 ng/mL for OTA compared with other direct or disposable electrochemical immunosensors. Real application in the spiked malt samples verified high accuracy with no matrix interferences of the proposed immunoseonsor. This is a meaningful study on a self-assembled electrochemical immunoseonsor for ultra-sensitive and rapid detection of OTA in malt samples, which suggested a general simple-to-use sensing platform and prospect as an economical and green tool for ultra-sensitive detection of much more trace-level of toxic small molecules in other complex matrices to ensure their quality and safety.


Assuntos
Ocratoxinas/análise , Poaceae/química , Anticorpos Monoclonais/imunologia , Espectroscopia Dielétrica , Técnicas Eletroquímicas/métodos , Eletrodos , Imunoensaio/métodos
10.
Environ Sci Pollut Res Int ; 27(12): 13081-13094, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32016874

RESUMO

The cleaning of metallic artworks is a crucial step for their preservation. Cleaning operations generally aim at removing deposits and corrosion layers, and all the non-stable and potentially reactive phases formed as a consequence of the interaction of the metal with the environment. Thus, all secondary-formed compounds and layers that can undermine the overall preservation of the artwork, both from the esthetic and the corrosion point of view, should be removed. On the other hand, superficial stable patinas contributing to the artistic and historic value of the objects and that may provide protection to the metallic surface should be preserved. The optimal cleaning procedure should be able to promote a long-term improvement of the corrosion resistance of the surfaces. Therefore, the long-term monitoring of the corrosion behavior of the cleaned surfaces with electrochemical techniques could provide valuable information for the selection of the optimal methodology. In this work, five cleaning procedures have been applied to five bronze sculptures. The cleaned surfaces have been characterized following a multi-analytical and non-invasive approach, and the long-term evolution of their corrosion behavior has been monitored by means of on-site non-invasive linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) measurements for more than 2 years.


Assuntos
Artefatos , Metais , Corrosão , Espectroscopia Dielétrica , Escultura
11.
J Nanobiotechnology ; 18(1): 11, 2020 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-31931815

RESUMO

BACKGROUND: In several years ago, infection with human papillomaviruses (HPVs), have been prevalent in the worlds especially HPV type 18, can lead to cervical cancer. Therefore, rapid, accurate, and early diagnosis of HPV for successful treatment is essential. The present study describes the development of a selective and sensitive electrochemical biosensor base on DNA, for early detection of HPV-18. For this purpose, a nanocomposite of reduced graphene oxide (rGO) and multiwalled carbon nanotubes (MWCNTs) were electrodeposited on a screen-printed carbon electrode (SPCE). Then, Au nanoparticles (AuNPs) were dropped on a modified SPCE. Subsequently, single strand DNA (ssDNA) probe was immobilized on the modified electrode. The link attached between AuNPs and probe ssDNA provided by L-cysteine via functionalizing AuNPs (Cys-AuNPs). The differential pulse voltammetry (DPV) assay was also used to electrochemical measurement. The measurement was based on the oxidation signals of anthraquninone-2-sulfonic acid monohydrate sodium salt (AQMS) before and after hybridization between the probe and target DNA. RESULTS: The calibration curve showed a linear range between 0.01 fM to 0.01 nM with a limit of detection 0.05 fM. The results showed that the optimum concentration for DNA probe was 5 µM. The good performance of the proposed biosensor was achieved through hybridization of DNA probe-modified SPCE with extracted DNA from clinical samples. CONCLUSIONS: According to the investigated results, this biosensor can be introduced as a proprietary, accurate, sensitive, and rapid diagnostic method of HPV 18 in the polymerase chain reaction (PCR) of real samples.


Assuntos
Técnicas Biossensoriais , DNA Viral/análise , Detecção Precoce de Câncer , Técnicas Eletroquímicas/métodos , Papillomavirus Humano 18/genética , Papillomavirus Humano 18/isolamento & purificação , Nanopartículas Metálicas/química , Nanotubos de Carbono/química , Neoplasias do Colo do Útero/diagnóstico , Neoplasias do Colo do Útero/virologia , Calibragem , Espectroscopia Dielétrica , Eletrodos , Feminino , Ouro , Humanos , Limite de Detecção , Nanopartículas Metálicas/ultraestrutura , Nanotubos de Carbono/ultraestrutura , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier
12.
Ecotoxicol Environ Saf ; 190: 110123, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31891837

RESUMO

In this work, a novel manganese dioxide-graphene nanosheets (MnO2-GNSs) composite was synthesized by a facile one-step hydrothermal method, in which manganese dioxide (MnO2) was fabricated by hydrothermal reduction of KMnO4 with GNSs. The structure and morphology of MnO2-GNSs composite were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) analysis and X-ray photoelectron spectroscopy (XPS). A sensitive non-enzymatic electrochemical sensor based on MnO2-GNSs composite for the detection of low concentration hydrogen peroxide (H2O2) was fabricated. The electrochemical properties of MnO2-GNSs composite modified glassy carbon electrode (MnO2-GNSs/GCE) were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and amperometry. The observations confirmed that the fabricated sensor exhibited high electrocatalytic activity for oxidation of H2O2 owing to the catalytic ability of MnO2 particles and the conductivity of GNSs. Under the optimum conditions, the calibration curve was linear for the amperometric response versus H2O2 concentration over the range 0.5-350 µM with a low detection limit of 0.19 µM (S/N = 3) and high sensitivity of 422.10 µA mM-1 cm-2. The determination and quantitative analysis of H2O2 in antiseptic solution on MnO2-GNSs/GCE exhibited percent recovery of 96.50%-101.22% with relative standard deviation (RSD) of 1.48%-4.47%. The developed MnO2-GNSs/GCE might be a promising platform for the practical detection of H2O2 due to its prominent properties including excellent reproducibility, good anti-interference and repeatability.


Assuntos
Técnicas Eletroquímicas/métodos , Grafite/química , Peróxido de Hidrogênio/análise , Compostos de Manganês/química , Modelos Químicos , Óxidos/química , Carbono/química , Catálise , Espectroscopia Dielétrica , Eletrodos , Limite de Detecção , Reprodutibilidade dos Testes
13.
Water Res ; 172: 115477, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31945650

RESUMO

The polymer coagulant aid can effectively enhance the coagulation-ultrafiltration (C-UF) process for the purification of drinking water. However, when coagulant aid entered the filtration, it may also cause serious membrane fouling as polymer. In-situ Raman spectroscopy and electrochemical impedance spectroscopy(EIS) were applied to monitor the effects of coagulant aids on the membrane. The causes of fouling were assisted discussed through stage cleaning of the membrane. The equivalent circuit fitting was performed on the EIS data and the Raman spectral data were statistically analyzed after peak fitting. EIS and the cluster analysis of Raman spectroscopy provided an earlier feedback on membrane fouling layers compared to flux. The cause of membrane fouling was explained via variation of characteristic functional groups obtained by Raman spectroscopy. When the molecular weight of the coagulant aid was 160 times,80 times and 16 times larger than the MWCO of the UF membrane, the equivalent circuit obtained by fitting the EIS of the UF system satisfied Rs + c(QpRp), Rs(QcRc)(QpRp) and Rs(Qt(Rc(QpRp))) respectively. Partial correlation analysis showed that the corresponding factors causing irreversible fouling of membrane were humic acid(HA), HA and coagulant aids, coagulant aids. Combined with the mean roughness (Ra) of membrane, the coagulant aid performed differently in the cleaning of contaminated membrane and also affected the cleaning of HA.


Assuntos
Ultrafiltração , Purificação da Água , Espectroscopia Dielétrica , Substâncias Húmicas , Membranas Artificiais , Análise Espectral Raman
14.
Food Chem ; 314: 126173, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-31954942

RESUMO

The detection of phospholipids oxidation is important for meat control and disease prevention. In this paper, a photoelectrochemical sensor based on printable mesoscopic chip (PMC) for fast and real-time monitoring phospholipids oxidation was designed and fabricated. TiO2, ZrO2 and carbon films of PMC were screen-printed onto the FTO glass layer by layer. The PMC and the feasibility for determination of phospholipids oxidation were investigated by scanning electron microscope (SEM), UV-vis spectroscopy, cyclic voltammograms (CVs) and electrochemical impedance spectroscopy (EIS), etc. The short circuit current (Jsc) was used as a signal current, which would decrease if phospholipids in PMC were undergoing oxidation for the change of electrical properties. Compared with other methods, phospholipids in PMC did not require pretreatment, and the process was nondestructive and real-time. Meanwhile, this method showed high sensitivity and good selectivity. The fabricating process of PMC is simple, and the costs are low, relatively.


Assuntos
Espectroscopia Dielétrica/instrumentação , Análise de Alimentos/instrumentação , Fosfolipídeos/análise , Carbono/química , Espectroscopia Dielétrica/métodos , Desenho de Equipamento , Análise de Alimentos/métodos , Lecitinas/análise , Lecitinas/química , Microscopia Eletrônica de Varredura , Oxirredução , Fosfolipídeos/química , Sensibilidade e Especificidade , Soja/química , Titânio/química
15.
Mater Sci Eng C Mater Biol Appl ; 108: 110465, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31924022

RESUMO

A biocompatible, cost-effective, and scalable reduced graphene oxide (rGO) film was obtained from shellac using thermal treatment and its structural, chemical, and electrical properties were investigated. This thermally-decomposed rGO (TrGO) film exhibited good crystallinity, low sheet resistance, and high carbon content. TrGO flakes obtained from the film were dispersed and drop cast onto indium tin oxide/glass electrodes to fabricate label-free electrochemical immunosensors for the quantitative detection of the influenza virus H1N1 via electrochemical impedance spectroscopy. These sensors exhibited high stability and reproducibility, both possibly ascribable to the high adhesion of TrGO due to its phenolic-OH moiety; the limits of detection were 26 and 33 plaque-forming units, respectively, in phosphate-buffered saline and diluted saliva. These cost-effective TrGO-based sensors showed great potential as reliable and robust nanomaterial-based biosensors for widespread clinical applications.


Assuntos
Técnicas Biossensoriais , Espectroscopia Dielétrica , Grafite/química , Vírus da Influenza A Subtipo H1N1 , Compostos de Estanho/química , Limite de Detecção
16.
Talanta ; 209: 120511, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31892041

RESUMO

An electrochemical immuno-nanogenosensor is developed based on noble-metal-free nickel phosphate nanostructure (NiPNs) as an excellent biocompatible material for miRNA detection in blood serum and urine samples without using indicators for the first time. The pompon flower-like morphology of NiPNs is synthesized, and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction pattern (XRD), fourier transform-infrared spectroscopy (FT-IR), and electrochemical impedance methods. The novel NiPNs nanostructured interface was constructed by coordinate covalent bonding between Ni and phosphate group of probe DNA. The constructed NiPNs-p-DNA surface served as the amplified hybridization platform enabling efficient access to numerous target microRNA sequences. As a result, the developed NiPFNs biosensing platform displayed excellent sensitivity, selectivity, and ultralow experimental limit-of-detection (LOD) of 0.034 pM (S/N = 3) as compared with other Ni phosphide nanostructures. This simple and efficient approach is highly suitable for the development of point-of-care detection systems. To the extent of our knowledge, this is the first report on trace level detection of miRNAs employing non-noble Ni metal nanostructures based biosensing platform.


Assuntos
MicroRNAs/sangue , MicroRNAs/urina , Nanoestruturas/química , Níquel/química , Fosfatos/química , Técnicas Biossensoriais/métodos , DNA/química , DNA/genética , Sondas de DNA/química , Sondas de DNA/genética , Espectroscopia Dielétrica , Limite de Detecção , MicroRNAs/genética , Hibridização de Ácido Nucleico
17.
Food Chem ; 310: 125820, 2020 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-31810725

RESUMO

In the present study, a sensitive label-free electrochemical aptasensor is introduced to measure aflatoxin M1 (AFM1) by using platinum nanoparticles (PtNPs) decorated on a glassy carbon electrode (GCE) modified with Fe-based metal-organic frameworks, MIL-101(Fe). The MIL-101(Fe) and the PtNP/MIL-101(Fe) are synthesized and characterized by Fourier transform infrared spectroscopy, X-ray diffraction, UV-Visible spectroscopy, and field-emission scanning electron microscopy. Cyclic voltammetry and electrochemical impedance spectroscopy (EIS) are done to monitor the fabrication processes of the aptasensor. In optimum conditions, the linear calibration range of 1.0 × 10-2 to 80.0 ng mL-1 and the detection limit of 2.0 × 10-3 ng mL-1 are obtained to measure AFM1 concentration using the EIS method. Finally, the fabricated aptasensor is successfully applied to measure AFM1 concentration in powder and pasteurized milk samples.


Assuntos
Aflatoxina M1/análise , Técnicas Eletroquímicas/métodos , Análise de Alimentos/métodos , Contaminação de Alimentos/análise , Leite/química , Animais , Aptâmeros de Peptídeos/química , Carbono , Espectroscopia Dielétrica/instrumentação , Espectroscopia Dielétrica/métodos , Técnicas Eletroquímicas/instrumentação , Eletrodos , Análise de Alimentos/instrumentação , Ferro/química , Limite de Detecção , Nanopartículas Metálicas/química , Estruturas Metalorgânicas/química , Pasteurização , Platina/química , Pós/análise , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X
18.
Food Chem ; 302: 125345, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31445377

RESUMO

This paper compares the results of standard chemical analytical processes and electrochemical impedance spectroscopy (EIS) in the characterization of different beverages, namely ground coffee, soluble coffee, coffee substitutes, barley, cow milk, vegetable drinks, tea, plant infusions and plant mixtures. For the two approaches, the similarities between the experimental data are assessed by means of the Euclidean and Canberra distances. The resulting information is processed by means of the multidimensional scaling (MDS) clustering and visualization algorithm. The results of the chemical analytical processes and EIS reveal identical clusters for the two adopted distances. Furthermore, the robustness of the experimental and computational scheme are assessed by means of the Procrustes technique. The results confirm the effectiveness of combining the EIS and MDS.


Assuntos
Bebidas/análise , Visualização de Dados , Espectroscopia Dielétrica/métodos , Algoritmos , Animais , Técnicas de Química Analítica/métodos , Análise por Conglomerados , Café/química , Espectroscopia Dielétrica/estatística & dados numéricos , Análise de Alimentos/métodos , Análise de Alimentos/estatística & dados numéricos , Leite/química , Processamento de Sinais Assistido por Computador , Chá/química
19.
Mater Sci Eng C Mater Biol Appl ; 106: 110013, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31753338

RESUMO

The degradation behavior of Mg-4 wt% Zn alloy with three different microstructures was examined in Hank's solution at 37 °C by electrochemical measurements and immersion tests in this study. The results show that the sample with cellular structure exhibits a more positive corrosion potential, lower corrosion current density, larger impedance and more protective film than samples with columnar dendritic and equiaxed dendritic structure. The higher corrosion resistance is attributed to the preferred orientation, eliminating susceptible grain boundaries and reduced secondary phases.


Assuntos
Ligas/metabolismo , Soluções Isotônicas/química , Ligas/química , Corrosão , Espectroscopia Dielétrica , Hidrogênio/química , Hidrogênio/metabolismo , Magnésio/química , Teste de Materiais , Microscopia Eletrônica de Varredura , Temperatura , Zinco/química
20.
Bioelectrochemistry ; 131: 107386, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31706116

RESUMO

The biocompatibility of human gingival fibroblasts (HGF) was evaluated in different concentrations of poly(vinyl alcohol) and sodium alginate (PVA/SA) nanofibres (3.5 wt% 4 wt% and 5 wt%). The PVA/SA nanofibres were deposited on the surface of an electrode microchip by using the electrospinning technique. Electrochemical impedance spectroscopy (EIS) was applied to measure the dielectric properties of each system. In order to provide a detailed analysis as well as a right physical interpretation of the EIS results, the data was fitted with an electric equivalent circuit based on the EIS and the microscopic assessments. The results registered three different time constants (TCs) of the PVA/SA scaffold which indicated different layers at different depths of the scaffold. The TCs changed their dielectric properties depending on the PVA/SA concentration. The 4 wt% system showed the highest biocompatibility properties, given that its resistance and electrochemical capacitance show the formation of a mature-stage cell interaction of HGF. The EIS data offers an exhaustive analysis of the biological activity of the cell response in real time to determine its biocompatibility features. Fluorescence analysis demonstrated a heterogeneous growth of the HGF on the PVA/SA scaffold surface.


Assuntos
Materiais Biocompatíveis , Espectroscopia Dielétrica/métodos , Gengiva/metabolismo , Tecidos Suporte , Fibroblastos/metabolismo , Gengiva/citologia , Humanos
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