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1.
Molecules ; 26(1)2020 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-33379393

RESUMO

Tubular-shaped layer electrodeposition from chitosan-hydroxyapatite colloidal solutions has found application in the field of regeneration or replacement of cylindrical tissues and organs, especially peripheral nerve tissue regeneration. Nevertheless, the quantitative and qualitative characterisation of this phenomenon has not been described. In this work, the colloidal systems are subjected to the action of an electric current initiated at different voltages. Parameters of the electrodeposition process (i.e., total charge exchanged, gas volume, and deposit thickness) are monitored over time. Deposit structures are investigated by scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). The value of voltage influences structural characteristics but not thickness of deposit for the process lasting at least 20 min. The calculated number of exchanged electrons for studied conditions suggests that the mechanism of deposit formation is governed not only by water electrolysis but also interactions between formed hydroxide ions and calcium ions coordinated by chitosan chains.


Assuntos
Quitosana/química , Durapatita/química , Galvanoplastia/métodos , Hidróxidos/química , Íons/química , Microscopia Eletrônica de Varredura/métodos , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Engenharia Tecidual/métodos , Tecidos Suporte/química , Água/química
2.
Chemosphere ; 261: 128157, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33113652

RESUMO

Porous titanium-based PbO2 electrodes were successfully fabricated by pulse electrodeposition method. The primary pulse electrodeposition parameters, including pulse frequency (f), duty ratio (γ), average current density (Ja) and electrodeposition time (t) were considered in this study. An orthogonal experiment was designed based on those four factors and in three levels. SEM images and XRD results suggest that the surface morphology and structure of PbO2 electrodes could be easily changed by varying pulse electrodeposition parameters. Orthogonal analysis reveals that the increase of f and Ja could decrease the average grain size of PbO2 electrodes, which is conducive to create more active sites and promote the generation of hydroxide radicals. The electrochemical degradation of Azophloxine was carried out to evaluate the electrochemical oxidation performance of pulse electrodeposited electrodes. The results indicate that the influences of four factors can be ranked as follow: Ja >γ≈ t > f. The higher f, larger Ja and longer t could facilitate the optimization of the integrated electrochemical degradation performance of prepared PbO2 electrode. The accelerated life time is dominated by Ja and t, coincident with the average weight increase of ß-PbO2 layer. The optimal parameters of pulse electrodeposition turn out to be: f = 50 Hz, γ = 30%, Ja = 25 mA cm-2, t = 60 min. Together, the consequences of the experiments give assistance to uncover and roughly conclude the mechanism of pulse electrodeposition.


Assuntos
Galvanoplastia/métodos , Chumbo/química , Modelos Teóricos , Óxidos/química , Titânio/química , Compostos Azo/análise , Eletrodos , Naftalenossulfonatos/análise , Oxirredução , Porosidade , Propriedades de Superfície , Águas Residuárias/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos
3.
J Chromatogr A ; 1628: 461486, 2020 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-32822970

RESUMO

In this work, an inexpensive, fast, and selective ionic liquid modified graphene oxide (GO-IL) was synthesized and electrochemically deposited on the inner surface of a stainless-steel tube. Then, it was applied for circulated headspace in-tube solid-phase microextraction (CHS-IT-SPME) of naphthalene from honey samples. Next, the coated tube was replaced with the sample loop of a six-port injection valve for on-line desorption and further HPLC-UV analysis of naphthalene. The sorbent was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), and energy-dispersive X-ray spectroscopy (EDX). Different parameters affecting the procedure efficiency, including extraction temperature, extraction time, salt concentration, and sample volume were optimized by central composite design and response surface methodology. Under the optimum conditions, the calibration curve was linear within the range of 0.3-200 ng mL-1, with a regression coefficient of 0.9972. The limits of detection (LOD) and quantification (LOQ) were found to be 0.1 ng mL-1 and 0.3 ng mL-1, respectively. Intra-day and inter-day RSDs% for three replicate measurements of naphthalene at the concentration of 10 ng mL-1 were obtained 3.9% and 5.0%, respectively. Also, good tube-to-tube reproducibility of 5.3% was achieved. Finally, the method was successfully applied for measuring trace amounts of naphthalene in honey samples. Relative recoveries were calculated within the range of 90.0-106.5%, indicating excellent efficiency of the proposed method.


Assuntos
Cromatografia Líquida/métodos , Galvanoplastia/métodos , Grafite/química , Mel/análise , Líquidos Iônicos/química , Naftalenos/isolamento & purificação , Sistemas On-Line , Microextração em Fase Sólida/métodos , Cromatografia Líquida de Alta Pressão , Limite de Detecção , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Reprodutibilidade dos Testes
4.
Chemosphere ; 259: 127488, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32640376

RESUMO

A Ce-doped Ti/PbO2 electrode was prepared in a deposition solution containing Ce3+ and Pb2+ ions by electrodeposition, and the surface morphology, crystal structure and elemental states were characterized by SEM, XRD and XPS. The electrode was used to investigate the simultaneous degradation of three phthalate esters (PAEs), i.e., dimethyl phthalate (DMP), diethyl phthalate (DEP) and dibutyl phthalate (DBP) in synthetic wastewaters. The results showed that the electrode exhibited excellent electrocatalytic activity and good reusability and stability, and the removal efficiencies of 5 mg L-1 DBP, DMP and DEP in 0.05 M Na2SO4 (pH 7) reached 98.2%, 95.8% and 81.1% at current density of 25 mA cm-2 after 10 h degradation, respectively. The degradation processes followed pseudo first-order kinetic model very well, and the observed rate constants of DBP, DEP and DMP were 0.42, 0.40 and 0.29 h-1, respectively. The energy consumption in three PAEs degradation was also assessed. The main degradation products of the three PAEs were identified by using liquid chromatography-tandem mass spectrometry, and the possible degradation pathways mainly included dealkylation, hydroxyl addition, decarboxylation and benzene ring cleavage. This work is a promising candidate for efficient treatment of multiple PAEs in wastewater and protection of the aquatic ecological environment.


Assuntos
Cério/química , Galvanoplastia/métodos , Recuperação e Remediação Ambiental/métodos , Ácidos Ftálicos/química , Águas Residuárias/química , Poluentes Químicos da Água/química , Dibutilftalato/química , Eletrodos , Ésteres/química , Chumbo/química , Óxidos/química , Titânio/química
5.
ACS Appl Mater Interfaces ; 12(10): 12018-12029, 2020 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-32037804

RESUMO

Electrophoretically deposited (EPD) polymer-based coatings have been extensively reported as reservoirs in medical devices for delivery of therapeutic agents, but control over drug release remains a challenge. Here, a simple but uncommon assembly strategy for EPD polymer coatings was proposed to improve drug release without introducing any additives except the EPD matrix polymer precursor. The added value of the proposed strategy was demonstrated by developing a novel EPD silk fibroin (SF) coating assembled from pre-assembled SF nanospheres for an application model, that is, preventing infections around percutaneous orthopedic implants via local delivery of antibiotics. The EPD mechanism of this nanosphere coating involved oxidation of water near the substrate to neutralize SF nanospheres, resulting in irreversible deposition. The deposition process and mass could be easily controlled using the applied EPD parameters. In comparison with the EPD SF coating assembled in a conventional way (directly obtained from SF molecule solutions), this novel coating had a similar adhesion strength but exhibited a more hydrophobic nanotopography to induce better fibroblastic response. Moreover, the use of nanospheres as building blocks enabled 1.38 and 21 times enhancement on the antibiotic release amount and time (of 95% maximum dug release), respectively, while retaining drug effectiveness and showing undetectable cytotoxicity. This unexpected release kinetics was found attributable to the electrostatic and hydrophobic interactions between the drug and nanospheres and a negligible initial dissolution effect on the nanosphere coating. These results illustrate the promising potential of the pre-assembled strategy on EPD polymer coatings for superior control over drug delivery.


Assuntos
Materiais Revestidos Biocompatíveis/química , Sistemas de Liberação de Medicamentos/métodos , Galvanoplastia/métodos , Fibroínas/química , Nanosferas/química , Animais , Antibacterianos/química , Antibacterianos/farmacocinética , Antibacterianos/farmacologia , Camundongos , Células NIH 3T3 , Staphylococcus aureus/efeitos dos fármacos , Vancomicina/química , Vancomicina/farmacocinética , Vancomicina/farmacologia
6.
J Vis Exp ; (155)2020 01 19.
Artigo em Inglês | MEDLINE | ID: mdl-32009655

RESUMO

Giant vesicles obtained from phospholipids and copolymers can be exploited in different applications: controlled and targeted drug delivery, biomolecular recognition within biosensors for diagnosis, functional membranes for artificial cells, and development of bioinspired micro/nano-reactors. In all of these applications, the characterization of their membrane properties is of fundamental importance. Among existing characterization techniques, micropipette aspiration, pioneered by E. Evans, allows the measurement of mechanical properties of the membrane such as area compressibility modulus, bending modulus and lysis stress and strain. Here, we present all the methodologies and detailed procedures to obtain giant vesicles from the thin film of a lipid or copolymer (or both), the manufacturing and surface treatment of micropipettes, and the aspiration procedure leading to the measurement of all the parameters previously mentioned.


Assuntos
Galvanoplastia/métodos , Lipossomas Unilamelares/química , Animais , Bovinos , Sistemas de Liberação de Medicamentos , Imageamento Tridimensional , Lipossomos , Micromanipulação , Polímeros/química , Pressão , Soroalbumina Bovina/química , Estresse Mecânico , Sucção , Compostos de Estanho/química
7.
Mikrochim Acta ; 187(1): 94, 2020 01 04.
Artigo em Inglês | MEDLINE | ID: mdl-31902014

RESUMO

Poly(3,4-ethylenedioxythiophene) (PEDOT) films were electrodeposited by cyclic voltammetry on a glassy carbon electrode (GCE) in aqueous solution. Three kinds of supporting electrolytes were used, viz. graphene oxide (GO), phosphate buffered saline (PBS), and GO in PBS, respectively. The surface morphology of the modified electrodes was characterized by scanning electron microscopy. The electrochemical performance of the modified electrodes was investigated by cyclic voltammetry and electrochemical impedance spectroscopy by using the hexacyanoferrate redox system. The results demonstrate that the PEDOT-GO/GCE, which was electropolymerized in aqueous solutions containing EDOT and GO, shows the best electrochemical activities compared with other modified electrodes. The electrochemical behaviors of ascorbic acid (AA), dopamine (DA) and uric acid (UA) were investigated by cyclic voltammetry. The PEDOT-GO/GCE exhibits enhanced electrocatalytic activities towards these important biomolecules. Under physiological pH conditions and in the mixed system of AA, DA and UA, the modified GCE exhibits the following figures of merit: (a) a linear voltammetric response in the concentration ranges of 100-1000 µM for AA, 6.0-200 µM for DA, and 40-240 µM for UA; (b) well separated oxidation peaks near 31, 213 and 342 mV (vs. saturated Ag/AgCl) for AA, DA and UA, respectively; and (c) detection of limits (at S/N = 3) of 20, 2.0 and 10 µM. The results demonstrate that GO, based on its relatively large number of anionic sites, can be used as the sole weak electrolyte and charge balance dopant for the preparation of functionally doped conducting polymers by electrodeposition. Graphical abstractSchematic representation of a nanostructure composed of hybrid conducting polymer PEDOT-GO nanocomposites, and its application to simultaneous determination of ascorbic acid, dopamine and uric acid.


Assuntos
Ácido Ascórbico/análise , Dopamina/análise , Técnicas Eletroquímicas/métodos , Ácido Úrico/análise , Compostos Bicíclicos Heterocíclicos com Pontes , Técnicas Eletroquímicas/normas , Eletrodos , Galvanoplastia/métodos , Ferrocianetos/química , Grafite , Oxirredução , Polímeros
8.
Mater Sci Eng C Mater Biol Appl ; 108: 110425, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31923935

RESUMO

Beta-type Ti-based alloys are promising new materials for bone implants owing to their excellent mechanical biofunctionality and biocompatibility. For treatment of fractures in case of systemic diseases like osteoporosis the generation of implant surfaces which actively support the problematic bone healing is a most important aspect. This work aimed at developing suitable approaches for electrodeposition of Sr-substituted hydroxyapatite (Srx-HAp) coatings onto Ti-45Nb. Potentiodynamic polarization measurements in electrolytes with 1.67 mmol/L Ca(NO3)2, which was substituted by 0, 10, 50 and 100% Sr(NO3)2, and 1 mmol/L NH4H2PO4 at 333 K revealed the basic reaction steps for OH- and PO43- formation needed for the chemical precipitation of Srx-HAp. Studies under potentiostatic control confirmed that partial or complete substitution of Ca2+- by Sr2+-ions in solution has a significant effect on the complex reaction process. High Sr2+-ion contents yield intermediate phases and a subsequent growth of more refined Srx-HAp coatings. Upon galvanostatic pulse-deposition higher reaction rates are controlled and in all electrolytes very fine needle-like crystalline coatings are obtained. With XRD the incorporation of Sr-species in the hexagonal HAp lattice is evidenced. Coatings formed in electrolytes with 10 and 50% Sr-nitrate were chemically analyzed with EDX mapping and GD-OES depth profiling. Only a fraction of the Sr-ions in solution is incorporated into the Srx-HAp coatings. Therein, the Sr-distribution is laterally homogeneous but non-homogeneous along the cross-section. Increasing Sr-content retards the coating thickness growth. Most promising coatings formed in the electrolyte with 10% Sr-nitrate were employed for Ca, P and Sr release analysis in Tris-Buffered Saline (150 mM NaCl, pH 7.6) at 310 K. At a sample surface: solution volume ratio of 1:200, after 24 h the amount of released Sr-ions was about 30-35% of that determined in the deposited Srx-HAp coating. In vitro studies with human bone marrow stromal cells (hBMSC) revealed that the released Sr-ions led to a significantly enhanced cell proliferation and osteogenic differentiation and that the Sr-HAp surface supported cell adhesion indicating its excellent cytocompatibility.


Assuntos
Ligas/química , Durapatita/química , Galvanoplastia/métodos , Estrôncio/química , Ligas/efeitos adversos , Durapatita/efeitos adversos , Humanos , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/efeitos dos fármacos
9.
Ultrason Sonochem ; 62: 104867, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31806551

RESUMO

For the first time, Bi2MoO6 nanofilms were successfully synthesized by simultaneous pulse sonication-pulse electrodeposition (PS-PED) on the stainless steel mesh surface. Bismuth molybdate films were formed under various combinations of electrodeposition and sonication (sono-electrodeposition) in continuous and pulse modes. Porous Bi2MoO6 films synthesized by PS-PED method and showed the highest efficiency in photocatalytic degradation in comparison with other films. Bi2MoO6 film obtained from PS-PED had a thickness of 13.78 nm while, the thickness for the electrodeposition method was 39.52 nm. The high photocatalytic efficiency is attributed to the high surface roughness and low thickness of film synthesized by PS-PED method. Indeed, ultrasound played a key role in the synthesis of films with high surface roughness. On the other hand, shock waves and micro-jets could be dissolved diffusion problems and reduced the dendrite like structures in deposition process. Simultaneous application of pulse modes for both combined methods led to more growth of crystallographic planes. This is due to reaction of ions on the surface in interval relaxation times and produce more nuclei for growth. In order to obtain a high efficiency, response surface methodology was used for optimization of effective variable parameters (ton, toff and sonication amplitude) in film preparation.


Assuntos
Anti-Inflamatórios não Esteroides/química , Bismuto/química , Diclofenaco/química , Galvanoplastia/métodos , Molibdênio/química , Nanoestruturas , Sonicação , Aço Inoxidável/química , Poluentes Químicos da Água/química , Catálise , Processos Fotoquímicos , Propriedades de Superfície
10.
Chemosphere ; 239: 124715, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31499311

RESUMO

Electrodeposition is an economical and efficient way to prepare Ti/SnO2-Sb electrode for electrochemical oxidizing pollutants in wastewater. The solvent used for electrodeposition has a great effect on electrode performance. The conventional Ti/SnO2-Sb electrode electrodeposited using aqueous solvent has poor electrochemical activity and short service life. In this study, a Ti/SnO2-Sb electrode was prepared via electrodeposition using a deep eutectic solvent (DES). This new Ti/SnO2-Sb-DES electrode performed a rate constant of 0.571 h-1 for methylene blue decolorization and long accelerated service life of 12.9 h (100 mA cm-2; 0.5 M H2SO4), which were 1.7 times and 3.2 times as high as that of the electrode prepared in aqueous solvent, respectively. The enhanced properties were related to the 1.3 times increased electrochemically active surface area of Ti/SnO2-Sb-DES electrode which had a rough, multilayer and uniform surface structure packed with nano-sized coating particles. In conclusion, this study developed a facile, green and efficient pathway to prepare Ti/SnO2-Sb electrode with high performance.


Assuntos
Antimônio/química , Técnicas Eletroquímicas/métodos , Galvanoplastia/métodos , Solventes/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Eletrodos/normas , Azul de Metileno/química , Oxirredução , Compostos de Estanho/química , Titânio/química , Águas Residuárias/química
11.
ACS Appl Mater Interfaces ; 11(47): 43936-43948, 2019 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-31696695

RESUMO

One-dimensional nanoneedle-like arrays have emerged as an attractive tool for penetrating the cell membrane to achieve intracellular applications including drug delivery, electrical recording, and biochemical detection. Hollow nanoneedles, also called nanostraws (NSs), combined with nanoelectroporation have been demonstrated as a powerful platform for intracellular drug delivery and extraction of intracellular contents. However, the fabrication technique of nanostraws still requires complicated and expensive atomic layer deposition and etching processes and fails to produce conductive nanostraws. Herein, we developed a commonly accessible and versatile electrodeposition approach to controllably fabricate conductive nanostraw arrays based on various types of metal or conductive polymer materials. Representatively, Pt nanostraws (Pt NSs) with 400 nm diameter were further integrated with a low-voltage nanoelectroporation system to achieve cell detection, intracellular drug delivery, and sensing of intracellular enzymes. Both theoretical simulations and experimental results revealed that the conductive nanostraws in direct contact with cells could induce high-efficiency cell electroporation at relatively low voltage (∼5 V). Efficient delivery of reagents into live cells with spatial control and repeated extraction of intracellular enzymes (e.g., caspase-3) for temporal monitoring from the same set of cells were demonstrated. This work not only pioneers a new avenue for universal production of conductive nanostraws on a large scale but also presents great potential for developing nanodevices to achieve a variety of biomedical applications including cell re-engineering, cell-based therapy, and signaling pathway monitoring.


Assuntos
Sistemas de Liberação de Medicamentos/instrumentação , Galvanoplastia/métodos , Desenho de Equipamento , Nanoestruturas/química , Técnicas Biossensoriais/instrumentação , Sobrevivência Celular , Células/química , Células/enzimologia , Condutividade Elétrica , Enzimas/análise , Células HeLa , Humanos , Nanotecnologia , Platina/química
12.
IET Nanobiotechnol ; 13(8): 829-833, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31625523

RESUMO

Human epidermal growth factor receptor 2 (HER-2) is overexpressed in 20-30% of human breast cancers, associated with poor prognosis and tumour aggression. The aim of this study was the production of trastuzumab-targeted Ecoflex nanoparticles (NPs) loaded with docetaxel and in vitro evaluation of their cytotoxicity and cellular uptake. The NPs were manufactured by electrospraying and characterised regarding size, zeta potential, drug loading, and release behaviour. Then their cytotoxicity was evaluated by MTT assay against an HER-2-positive cell line, BT-474, and an HER-2-negative cell line, MDA-MB-468. The cellular uptake was studied by flow cytometry and fluorescent microscope. The particle size of NPs was in an appropriate range, with relatively high drug entrapment and acceptable release efficiency. The results showed no cytotoxicity for the polymer, but the significant increment of cytotoxicity was observed by treatment with docetaxel-loaded NPs in both HER-2-positive and HER-2-negative cell lines, in comparison with the free drug. The trastuzumab-targeted NPs also significantly enhanced cytotoxicity against BT-474 cells, compared with non-targeted NPs.


Assuntos
Materiais Revestidos Biocompatíveis/síntese química , Docetaxel/administração & dosagem , Portadores de Fármacos/síntese química , Galvanoplastia/métodos , Nanopartículas/química , Poliésteres/química , Trastuzumab/química , Antineoplásicos/administração & dosagem , Antineoplásicos/farmacocinética , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Materiais Revestidos Biocompatíveis/química , Materiais Revestidos Biocompatíveis/uso terapêutico , Docetaxel/farmacocinética , Portadores de Fármacos/química , Portadores de Fármacos/farmacocinética , Composição de Medicamentos/métodos , Sistemas de Liberação de Medicamentos/métodos , Liberação Controlada de Fármacos , Ensaios de Seleção de Medicamentos Antitumorais , Feminino , Humanos , Nanoconjugados/química , Nanoconjugados/uso terapêutico , Nanopartículas/uso terapêutico , Tamanho da Partícula , Poliésteres/síntese química , Poliésteres/uso terapêutico
13.
Biosens Bioelectron ; 146: 111741, 2019 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-31586765

RESUMO

The design and fabrication of high visible-light activated photoelectrode are essential to precisely detect biomolecule in biological system. Herein, an ultrasensitive photoelectrochemical (PEC) aptasensor for specific recognition of adenosine is established based on carbon dots sensitized-amorphous molybdenum sulfide (a-MoSx/CDs) photoanode and dual amplification strategy. The heterostructured photoanode achieved by sequential electrodeposition reveals significantly boosted photocurrent with good stability and repeatability under visible light illumination, giving the credit to highly activated visible light absorption, uniform coverage and good electric contact to the underlying substrate, as well as the energy-band alignment between the two components. By stepwisely immobilizing complementary DNA probe (NH2-DNA) and adenosine aptamer (Apt), followed by methylene blue (MB) binding with the guanine base on Apt, a dual amplified self-powered PEC aptasensor for adenosine detection is constructed. Based on the co-sensitization effect of CDs and MB, ultrasensitive and high-affinitive determination of adenosine is realized over the concentration range of 0.01 nM-1000 nM at 0 V (vs. SCE), with satisfactory stability and reproducibility. The detection limit is as low as 3.3 pM, demonstrating a performance even surpassing most of the sensors reported so far. The prospective application of the co-sensitized a-MoSx photoanode for ultrasensitive aptasensing is highlighted in this work.


Assuntos
Adenosina/sangue , Aptâmeros de Nucleotídeos/química , Técnicas Biossensoriais/métodos , Dissulfetos/química , Molibdênio/química , Pontos Quânticos/química , Adenosina/análise , Técnicas Eletroquímicas/métodos , Galvanoplastia/métodos , Humanos , Luz , Limite de Detecção
14.
J Neural Eng ; 17(1): 016015, 2019 12 23.
Artigo em Inglês | MEDLINE | ID: mdl-31652427

RESUMO

OBJECTIVE: To systematically compare the in vitro electrochemical and mechanical properties of several electrode coatings that have been reported to increase the efficacy of medical bionics devices by increasing the amount of charge that can be delivered safely to the target neural tissue. APPROACH: Smooth platinum (Pt) ring and disc electrodes were coated with reduced graphene oxide, conductive hydrogel, or electrodeposited Pt-Ir. Electrodes with coatings were compared with uncoated smooth Pt electrodes before and after an in vitro accelerated aging protocol. The various coatings were compared mechanically using the adhesion-by-tape test. Electrodes were stimulated in saline for 24 hours/day 7 days/week for 21 d at 85 °C (1.6-year equivalence) at a constant charge density of 200 µC/cm2/phase. Electrodes were graded on surface corrosion and trace analysis of Pt in the electrolyte after aging. Electrochemical measurements performed before, during, and after aging included electrochemical impedance spectroscopy, cyclic voltammetry, and charge injection limit and impedance from voltage transient recordings. MAIN RESULTS: All three coatings adhered well to smooth Pt and exhibited electrochemical advantage over smooth Pt electrodes prior to aging. After aging, graphene coated electrodes displayed a stimulation-induced increase in impedance and reduction in the charge injection limit (p  < 0.001), alongside extensive corrosion and release of Pt into the electrolyte. In contrast, both conductive hydrogel and Pt-Ir coated electrodes had smaller impedances and larger charge injection limits than smooth Pt electrodes (p  < 0.001) following aging regardless of the stimulus level and with little evidence of corrosion or Pt dissolution. SIGNIFICANCE: This study rigorously tested the mechanical and electrochemical performance of electrode coatings in vitro and provided suitable candidates for future in vivo testing.


Assuntos
Materiais Revestidos Biocompatíveis/química , Técnicas Eletroquímicas/métodos , Galvanoplastia/métodos , Grafite/química , Hidrogéis/química , Platina/química , Implantes Cocleares , Estimulação Elétrica/instrumentação , Estimulação Elétrica/métodos , Técnicas Eletroquímicas/instrumentação , Eletrodos Implantados
15.
Mater Sci Eng C Mater Biol Appl ; 104: 109880, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31500020

RESUMO

The direct electron transfer and enzyme catalytic activity were investigated in electrochemical biosensor based on glucose oxidase (GOx) and electrochemical reduced graphene oxide-poly-(l-lysine) (ERGO-PLL) hybrid composite film embedded in a biocompatible matrix of Nafion. The ERGO-PLL was fabricated onto glassy carbon electrode (GCE) through one step electrodeposition of RGO incorporating PLL from graphene oxide-l-lysine aqueous dispersion. The fabrication process of Nafion/GOx/ERGO-PLL/GCE has been characterized by cyclic voltammetry and electrochemical impedance spectroscopy, and the surface morphology of modified electrodes were characterized by scanning electron microscopy. A pair of well-defined redox peaks with formal potential and peak separation of -0.461 V and 30 mV were observed at scan rate of 50 mV s-1, the electron transfer rate constant was calculated to be 18.7 s-1, demonstrated that direct electron transfer between immobilized GOx with ERGO-PLL and GCE was achieved. Moreover, the fabricated enzyme biosensor exhibited excellent electrocatalytic activity for determination of glucose in O2-free PBS (7.40) with linear voltammetric response from 0.005 to 9.0 mmol L-1, and detection limits (S/N = 3) of 2.0 µmol L-1. This work indicates that ERGO-PLL based modified electrode is superior to that of graphene based, and could be applied in biosensors, bioelectronics and electrocatalysis, etc.


Assuntos
Glucose Oxidase/química , Glucose/química , Grafite/química , Lisina/química , Técnicas Biossensoriais/métodos , Carbono/química , Catálise , Técnicas Eletroquímicas/métodos , Eletroquímica/métodos , Eletrodos , Galvanoplastia/métodos , Enzimas Imobilizadas/química , Concentração de Íons de Hidrogênio , Nanocompostos/química , Oxirredução , Polimerização
16.
J Mater Sci Mater Med ; 30(9): 99, 2019 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-31455977

RESUMO

Adipose-derived mesenchymal stem cells (ASCs) accelerate the osteointegration of bone grafts and improve the efficiency in the formation of uniform bone tissue, providing a practical and clinically attractive approach in bone tissue regeneration. In this work, the effect of nanofibrous biomimetic matrices composed of poly(ε-caprolactone) (PCL), nanometric hydroxyapatite (nHA) particles and 14-3-3 protein isoform epsilon on the initial stages of human ASCs (hASCs) osteogenic differentiation was investigated. The cells were characterized by flow cytometry and induction to differentiation to adipogenic and osteogenic lineages. The isolated hASCs were induced to differentiate to osteoblasts over all scaffolds, and adhesion and viability of the hASCs were found to be similar. However, the activity of alkaline phosphatase (ALP) as early osteogenic marker in the PCL-nHA/protein scaffold was four times higher than in PCL-nHA and more than five times than the measured in neat PCL.


Assuntos
Proteínas 14-3-3 , Durapatita , Células-Tronco Mesenquimais/efeitos dos fármacos , Osteogênese/efeitos dos fármacos , Poliésteres , Tecidos Suporte/química , Proteínas 14-3-3/química , Proteínas 14-3-3/farmacologia , Diferenciação Celular/efeitos dos fármacos , Diferenciação Celular/fisiologia , Células Cultivadas , Durapatita/química , Durapatita/farmacologia , Galvanoplastia/métodos , Humanos , Teste de Materiais , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/fisiologia , Nanofibras/química , Osteoblastos/efeitos dos fármacos , Osteoblastos/fisiologia , Osteogênese/fisiologia , Poliésteres/química , Poliésteres/farmacologia , Gordura Subcutânea Abdominal/citologia , Propriedades de Superfície/efeitos dos fármacos , Engenharia Tecidual/métodos
17.
Biosens Bioelectron ; 142: 111577, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31430613

RESUMO

A novel nonsemiconductor photoelectrochemical biosensor was first constructed using the unique plasmonic AuNi nanodendrite arrays. The AuNi nanodendrite arrays were rapidly prepared by a one-step electrodeposition method using the porous anodic aluminum templates. Owing to its hierarchical structure with abundant active sites, the synergistic catalytic of Au and Ni can be better exploited. These plasmonic AuNi nanodendrite arrays display exceptional photoelectrocatalytic activities for glucose oxidation and hydrogen peroxide reduction reaction under visible light illumination. Specifically, the detection sensitivity for glucose (3.7277 mA mM-1 cm-2) under illumination is about 3.3 folds improvement than in the dark (1.1287 mA mM-1 cm-2), together with high accuracy and low detection limit of 3 µM. The markedly enhanced performance of AuNi nanodendrite arrays can be attributed to its hierarchical structure with abundant active sites and plasmonic effect of Au with strong absorption band in visible region. Such a newly developed method via the facile and low-cost route is of great significance in designing the plasmon-aided photoelectrochemical biosensors.


Assuntos
Técnicas Biossensoriais/métodos , Glicemia/análise , Ouro/química , Peróxido de Hidrogênio/análise , Nanoestruturas/química , Níquel/química , Técnicas Eletroquímicas/métodos , Galvanoplastia/métodos , Humanos , Limite de Detecção , Masculino , Nanoestruturas/ultraestrutura , Semicondutores
18.
Chemosphere ; 236: 124330, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31319309

RESUMO

Shear-induced dissociation coupling with ultrafiltration (SID-UF) is an efficient and environment-friendly technology for the separation of heavy metal ions. In this paper, SID-UF was successfully employed for the selective recovery of nickel, zinc and copper from electroplating effluent using poly (acrylic acid) sodium (PAAS) and copolymer of maleic acid and acrylic acid (PMA) as complexants, respectively. The effects of the pH, mass ratio of polymer to metal ions (P/M) and the rotating speed on the metals removal efficiency are discussed in detail. The shear stabilities of the polymer-metal complexes were explored and the complexes critical shear rates (γc) were calculated. The results show that the order of the shear stabilities of PAA-metal complex is PAA-Zn > PAA-Cu > PAA-Ni, and that of PMA-metal complex is PMA-Cu > PMA-Ni > PMA-Zn. In addition, the construction of the stable structures of complexes and the calculation of the energies of the frontier molecular orbital by density functional theory method further predict and confirm the shear stabilities of the polymer-metal complexes.


Assuntos
Galvanoplastia/métodos , Metais Pesados/química , Ultrafiltração/métodos
19.
Int J Nanomedicine ; 14: 3929-3941, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31213809

RESUMO

Introduction: Hierarchical nanofibrous scaffolds are emerging as a promising bone repair material due to their high cell adhesion activity and nutrient permeability. However, the existing method for hierarchical nanofibrous scaffolds fabrication is complicated and not perfectly suitable for further biomedical application in view of both structure and function. In this study, we constructed a hierarchical nanofibrous poly (l-lactic acid)/poly(ε-caprolactone) (PLLA/PCL) scaffold and further evaluated its bone healing ability. Methods: The hierarchical PLLA/PCL nanofibrous scaffold (PLLA/PCL) was prepared by one-pot TIPS and then rapidly mineralized at room temperature by an electrochemical deposition technique. After electrode-positioning at 2 V for 2 hrs, a scaffold coated with hydroxyapatite (M-PLLA/PCL) could be obtained. Results: The pore size of the M-PLLA/PCL scaffold was hierarchically distributed so as to match the biophysical structure for osteoblast growth. The M-PLLA/PCL scaffold showed better cell proliferation and osteogenesis activity compared to the PLLA/PCL scaffold. Further in vivo bone repair studies indicated that the M-PLLA/PCL scaffold could accelerate defect healing in 12 weeks. Conclusion: The results of this study implied that the as-prepared hydroxyapatite coated hierarchical PLLA/PCL nanofibrous scaffolds could be developed as a promising material for efficient bone tissue repair after carefully tuning the TIPS and electrodeposition parameters.


Assuntos
Regeneração Óssea/fisiologia , Galvanoplastia/métodos , Minerais/química , Nanofibras/química , Copolímero de Ácido Poliláctico e Ácido Poliglicólico/farmacologia , Tecidos Suporte/química , Fosfatase Alcalina/metabolismo , Animais , Adesão Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Eletricidade , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/efeitos dos fármacos , Células-Tronco Mesenquimais/ultraestrutura , Osteogênese/efeitos dos fármacos , Porosidade , Ratos Sprague-Dawley , Crânio/diagnóstico por imagem , Crânio/efeitos dos fármacos , Crânio/patologia , Fatores de Tempo , Engenharia Tecidual/métodos , Microtomografia por Raio-X
20.
Work ; 63(3): 355-360, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31227679

RESUMO

BACKGROUND: Metal co-exposure of human subjects is an important matter of public health concern. It has been shown that Acetylcholinesterase activity is a suitable biomarker for the neurological risk assessment of some metals. A few studies have reported neurotoxicity risk among humans in co-exposure to chromium and nickel. OBJECTIVE: In this study, AChE activity was assessed in occupational exposure to chromium (VI) and co-exposure to nickel (II) and chromium (VI). METHODS: Air sampling was done in chromium electroplating workshops with the NIOSH 7600 and OSHA ID-121 methods for chromium and nickel assessment. Thirty-two workers from hard chromium plating and 30 from decorative chromium plating were evaluated, while AChE activity was measured by the Elman method. RESULTS: Personal exposure to chromium in 20% of the studied people exceeded the TWA set by ACGIH. Occupational exposure to nickel in 47% of the DCP subjects was found to be higher than TWA. Cholinergic inhibition in plating workers was marked by a decrease in AChE compared to controls. Subjects with chromium (VI) exposure contained significantly higher inhibition of AChE activity (p < 0.001) than workers with co-exposure to nickel (II) and chromium (VI). CONCLUSIONS: The chromium-matched electroplaters have no significant difference in AChE activity. It can be concluded that cholinergic inhibition with chromium (VI) is higher than nickel (II) exposure.


Assuntos
Galvanoplastia/métodos , Exposição Ocupacional/efeitos adversos , Medição de Risco/métodos , Adulto , Cromo/efeitos adversos , Monitoramento Ambiental/métodos , Humanos , Masculino , Pessoa de Meia-Idade , Níquel/efeitos adversos
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