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1.
ACS Appl Mater Interfaces ; 13(6): 7784-7791, 2021 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-33533611

RESUMO

Recently, flexible neuromorphic devices have attracted extensive attention for the construction of perception cognitive systems with the ultimate objective to achieve robust computation, efficient learning, and adaptability to evolutionary changes. In particular, the design of flexible neuromorphic devices with data processing and arithmetic capabilities is highly desirable for wearable cognitive platforms. Here, an albumen-based protein-gated flexible indium tin oxide (ITO) ionotronic neuromorphic transistor was proposed. First, the transistor demonstrates excellent mechanical robustness against bending stress. Moreover, spike-duration-dependent synaptic plasticity and spike-amplitude-dependent synaptic plasticity behaviors are not affected by bending stress. With the unique protonic gating behaviors, neurotransmission processes in biological synapses are emulated, exhibiting three characteristics in neurotransmitter release, including quantal release, stochastic release, and excitatory or inhibitory release. In addition, three types of spike-timing-dependent plasticity learning rules are mimicked on the ITO ionotronic neuromorphic transistor. Most interestingly, algebraic arithmetic operations, including addition, subtraction, multiplication, and division, are implemented on the protein gated neuromorphic transistor for the first time. The present work would open a promising biorealistic avenue to the scientific community to control and design wearable "green" cognitive platforms, with potential applications including but not limited to intelligent humanoid robots and replacement neuroprosthetics.


Assuntos
Albuminas/química , Neurotransmissores/química , Óxidos/química , Compostos de Estanho/química , Plasticidade Neuronal , Tamanho da Partícula , Propriedades de Superfície , Transistores Eletrônicos
2.
ACS Appl Mater Interfaces ; 13(2): 2204-2217, 2021 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-33399455

RESUMO

In this article, we demonstrate that specifically engineered oxide nanoparticles (NPs) have the potential to act as theranostic materials that are able to generate or prevent oxidative stress through their oxi-redox activity in various types of malignant and nonmalignant cells. The oxi-redox activity is related to the type and presence of surface defects, which is modified with appropriate synthesis conditions. In the present work, we used MDA-MB-231 and MCF-7 human breast cancer cells and nonmalignant MCF-10A human breast cells to demonstrate how controlled oxidative stress mediated by specifically nanoengineered indium tin oxide (ITO) NPs can selectively induce cell death in the cancer cells while reducing the oxidative stress in the normal cells and supporting their proliferation. The ITO NPs are also promising nanotheranostic materials for cancer therapy and contrast agents because of their multimodal imaging capabilities. We demonstrate that the synthesized ITO NPs can selectively increase the generation of reactive oxygen species (ROS) in both breast tumor cell lines, resulting in activation of apoptosis, and can also greatly suppress the cellular proliferation in both types of tumor cells. In contrast, the ITO NPs exhibit ROS scavenging-like behavior, significantly decreasing the ROS levels in MCF-10A cells exposed to the additional ROS, hydrogen peroxide (H2O2), so that they protect the proliferation of nonmalignant MCF-10A cells from ROS damage. In addition, fluorescent microscopy images revealed that the ITO NPs emit strong fluorescence that could be used to reveal their location. Moreover, computed tomography imaging demonstrated that the ITO NPs exhibited a comparable capability toward anatomical contrast enhancement. These results suggest that the synthesized ITO NPs have the potential to be a novel selective therapeutic agent with a multimodal imaging property for anticancer treatment.


Assuntos
Neoplasias da Mama/tratamento farmacológico , Nanopartículas , Estresse Oxidativo/efeitos dos fármacos , Compostos de Estanho/farmacologia , Antioxidantes/química , Antioxidantes/farmacologia , Apoptose/efeitos dos fármacos , Neoplasias da Mama/diagnóstico por imagem , Neoplasias da Mama/metabolismo , Linhagem Celular , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Feminino , Humanos , Células MCF-7 , Nanopartículas/química , Oxidantes/química , Oxidantes/farmacologia , Oxirredução , Espécies Reativas de Oxigênio/metabolismo , Nanomedicina Teranóstica , Compostos de Estanho/química , Tomografia Computadorizada por Raios X
3.
Chemosphere ; 261: 128201, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33113663

RESUMO

In this work, Ti/SnO2-RuO2 dimensionally stable anode has been successfully fabricated via thermal decomposition method and further used for highly efficient electrocatalytic degradation of alizarin cyanin green (ACG) dye wastewater. The morphology, crystal structure and composition of Ti/SnO2-RuO2 electrode are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray fluorescence spectroscopy (XRF), respectively. The result of accelerated life test suggests that as-prepared Ti/SnO2-RuO2 anode exhibits excellent electrochemical stability. Some parameters, such as reaction temperature, initial pH, electrode spacing and current density, have been investigated in detail to optimize the degradation condition of ACG. The results show that the decolorization efficiency and chemical oxygen demand removal efficiency of ACG reach up to 80.4% and 51.3% after only 40 min, respectively, under the optimal condition (reaction temperature 25 °C, pH 5, electrode spacing 1.0 cm and current density 3 mA cm-2). Furthermore, the kinetics analysis reveals that the process of electrocatalytic degradation of ACG follows the law of quasi-first-order kinetics. The excellent electrochemical activity demonstrates that the Ti/SnO2-RuO2 electrode presents a favorable application prospect in the electrochemical treatment of anthraquinone dye wastewater.


Assuntos
Antraquinonas/química , Carbocianinas/química , Eletrodos , Eliminação de Resíduos Líquidos/instrumentação , Análise da Demanda Biológica de Oxigênio , Corantes/química , Concentração de Íons de Hidrogênio , Microscopia Eletrônica de Varredura , Oxirredução , Compostos de Rutênio/química , Espectrometria por Raios X , Temperatura , Compostos de Estanho/química , Titânio/química , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Poluentes Químicos da Água/química , Difração de Raios X
4.
Nat Commun ; 11(1): 5391, 2020 10 26.
Artigo em Inglês | MEDLINE | ID: mdl-33106489

RESUMO

Acceleration and unification of drug discovery is important to reduce the effort and cost of new drug development. Diverse chemical and biological conditions, specialized infrastructure and incompatibility between existing analytical methods with high-throughput, nanoliter scale chemistry make the whole drug discovery process lengthy and expensive. Here, we demonstrate a chemBIOS platform combining on-chip chemical synthesis, characterization and biological screening. We developed a dendrimer-based surface patterning that enables the generation of high-density nanodroplet arrays for both organic and aqueous liquids. Each droplet (among > 50,000 droplets per plate) functions as an individual, spatially separated nanovessel, that can be used for solution-based synthesis or analytical assays. An additional indium-tin oxide coating enables ultra-fast on-chip detection down to the attomole per droplet by matrix-assisted laser desorption/ionization mass spectrometry. The excellent optical properties of the chemBIOS platform allow for on-chip characterization and in-situ reaction monitoring in the ultraviolet, visible (on-chip UV-Vis spectroscopy and optical microscopy) and infrared (on-chip IR spectroscopy) regions. The platform is compatible with various cell-biological screenings, which opens new avenues in the fields of high-throughput synthesis and drug discovery.


Assuntos
Avaliação Pré-Clínica de Medicamentos/métodos , Ensaios de Triagem em Larga Escala/métodos , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Dendrímeros/química , Avaliação Pré-Clínica de Medicamentos/instrumentação , Ensaios de Triagem em Larga Escala/instrumentação , Humanos , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Compostos de Estanho/química
5.
Int J Nanomedicine ; 15: 8037-8043, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33116516

RESUMO

Background: Artificial synaptic behaviors are necessary to investigate and implement since they are considered to be a new computing mechanism for the analysis of complex brain information. However, flexible and transparent artificial synapse devices based on thin-film transistors (TFTs) still need further research. Purpose: To study the application of flexible and transparent thin-film transistors with nanometer thickness on artificial synapses. Materials and Methods: Here, we report the design and fabrication of flexible and transparent artificial synapse devices based on TFTs with polyethylene terephthalate (PET) as the flexible substrate, indium tin oxide (ITO) as the gate and a polyvinyl alcohol (PVA) grid insulating layer as the gate insulation layer at room temperature. Results: The charge and discharge of the carriers in the flexible and transparent thin-film transistors with nanometer thickness can be used for artificial synaptic behavior. Conclusion: In summary, flexible and transparent thin-film transistors with nanometer thickness can be used as pressure and temperature sensors. Besides, inherent charge transfer characteristics of indium gallium zinc oxide semiconductors have been employed to study the biological synapse-like behaviors, including synaptic plasticity, excitatory postsynaptic current (EPSC), paired-pulse facilitation (PPF), and long-term memory (LTM). More precisely, the spike rate plasticity (SRDP), one representative synaptic plasticity, has been demonstrated. Such TFTs are interesting for building future neuromorphic systems and provide a possibility to act as fundamental blocks for neuromorphic system applications.


Assuntos
Nanopartículas/química , Nanotecnologia/instrumentação , Transistores Eletrônicos , Eletrodos , Gálio/química , Índio/química , Maleabilidade , Compostos de Estanho/química , Óxido de Zinco/química
6.
Nat Commun ; 11(1): 4768, 2020 09 21.
Artigo em Inglês | MEDLINE | ID: mdl-32958747

RESUMO

Detection and identification of proteins are typically achieved by analyzing protein size, charge, mobility and binding to antibodies, which are critical for biomedical research and disease diagnosis and treatment. Despite the importance, measuring these quantities with one technology and at the single-molecule level has not been possible. Here we tether a protein to a surface with a flexible polymer, drive it into oscillation with an electric field, and image the oscillation with a near field optical imaging method, from which we determine the size, charge, and mobility of the protein. We also measure antibody binding and conformation changes in the protein. The work demonstrates a capability for comprehensive protein analysis and precision protein biomarker detection at the single molecule level.


Assuntos
Proteínas/química , Proteínas/metabolismo , Imagem Individual de Molécula/métodos , Análise de Fourier , Ligantes , Polietilenoglicóis/química , Ligação Proteica , Conformação Proteica , Eletricidade Estática , Compostos de Estanho/química
7.
J Vis Exp ; (160)2020 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-32597874

RESUMO

The method presented uses mass spectrometry imaging (MSI) to establish the metabolic profile of S. alba leaves when exposed to xenobiotics. Using a non-targeted approach, plant metabolites and xenobiotics of interest are identified and localized in plant tissues to uncover specific distribution patterns. Then, in silico prediction of potential metabolites (i.e., catabolites and conjugates) from the identified xenobiotics is performed. When a xenobiotic metabolite is located in the tissue, the type of enzyme involved in its alteration by the plant is recorded. These results were used to describe different types of biological reactions occurring in S. alba leaves in response to xenobiotic accumulation in the leaves. The metabolites were predicted in two generations, allowing the documentation of successive biological reactions to transform xenobiotics in the leaf tissues.


Assuntos
Imageamento Tridimensional , Folhas de Planta/química , Salix/química , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Xenobióticos/metabolismo , Metaboloma , Compostos de Estanho/química , Xenobióticos/química
8.
Food Chem ; 324: 126889, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32353659

RESUMO

Pesticides have been extensively applied worldwide to protect crops from worms and insects; however, the continuous use of pesticides affects ecosystems, agricultural product safety, nontarget organisms, and human health. In this paper, we report a highly sensitive biosensor for the determination of pesticides based on tin sulfide (SnS2) and chitosan (CHIT) nanocomposites decorated with a unique British housefly acetylcholinesterase (AChE). The hydrothermally synthesized nano-SnS2 mixed with chitosan solution (CHIT-SnS2) was drop-casted onto a glassy carbon electrode (GCE). Subsequently, the British housefly AChE was immobilized on the CHIT/SnS2-coated GCE that was then employed for pesticide detection. The developed biosensor showed an ultra-high sensitivity and wide linear detection range from 0.02 nM to 20000 nM with a detection limit of 0.02 nM for the detection of chlorpyrifos as the model pesticide. Furthermore, the AChE/CHIT-SnS2/GCE exhibited acceptable storage stability, good reproducibility, and selectivity.


Assuntos
Acetilcolinesterase/metabolismo , Técnicas Biossensoriais/métodos , Quitosana/química , Moscas Domésticas/enzimologia , Compostos Organofosforados/análise , Sulfetos/química , Compostos de Estanho/química , Acetilcolinesterase/química , Animais , Carbono/química , Clorpirifos/análise , Técnicas Eletroquímicas , Eletrodos , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Limite de Detecção , Nanocompostos/química , Praguicidas/análise , Reprodutibilidade dos Testes
9.
Chemosphere ; 255: 126973, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32402889

RESUMO

Ti/SnO2-Sb is a promising anode for electrochemical advanced oxidation process with advantages of low cost and no secondary pollution, while suffers from low work economy due to the short service life. In this study, a facile strategy was proposed to fabricate Ti/SnO2-Sb electrode with high oxidation ability and long service life based on novelly sealing electrodeposited Sn-Sb coating with stannous citrate complex. The treated Ti/SnO2-Sb electrode exhibited an accelerated service life of 41.5 h (100 mA cm-2; 0.5 M H2SO4) and a degradation rate constant for methylene blue dye of 1.02 h-1 which were respectively 11.9 and 2.5 times as that of the untreated electrode. It was found out that the complex could well repair the coating defects inside or outside and form a covering film to tighten the coating, and was then mineralized during the following calcination process to achieve a uniform, rough and highly active SnO2-Sb catalytic layer. The distinctive structure was confirmed by XRD, SEM, XPS and FT-IR. The sealing treatment could be achieved by in situ electrodepositing Sn-Sb coating from or ex situ dipping Sn-Sb coating in solution containing stannous citrate complex followed by drying in air. This study provided a novel, facile and effective strategy to enhance performance of Ti/SnO2-Sb electrode that could be easily achieved in both laboratory and industrial scales and combined with other strategies.


Assuntos
Citratos/química , Modelos Químicos , Compostos de Estanho/química , Catálise , Ácido Cítrico , Eletrodos , Galvanoplastia , Azul de Metileno , Oxirredução , Espectroscopia de Infravermelho com Transformada de Fourier , Titânio/química
10.
Mikrochim Acta ; 187(5): 276, 2020 04 19.
Artigo em Inglês | MEDLINE | ID: mdl-32307592

RESUMO

A bimetallic nanostructure of Co/Cu for the non-enzymatic determination of glucose is presented. The heterostructure includes cobalt thin film on a porous array of Cu nanocolumns. Glancing angle deposition (GLAD) method was used to grow Cu nanocolumns directly on a fluorine-doped tin oxide (FTO) substrate. Then a thin film of cobalt was electrodeposited on the Cu nanostructures. Various characterization studies were performed in order to define the optimum nanostructure for the determination of glucose. The results showed remarkable boosting of the electrocatalytic activity of Co/Cu bimetallic structure compare to the responses achieved by the monometallic structures of Co or Cu. The sensor showed two linear response ranges for the determination of glucose at 0.55 V in 0.1 M NaOH, from 5 µM-1 mM and 2-9 mM. The sensitivity was 1741 (µA mM-1 cm-2) and 626 (µA mM-1 cm-2), respectively, while the detection limit for a signal-to-noise ratio of 3 was found to be 0.4 µM. The sensor exhibited excellent selectivity and was successfully applied to the determination of glucose in real human blood serum samples. Graphical Abstract Schematic representation of fabrication process of the glucose sensor of Co (Cobalt)/Cu (Copper) on Fluorine doped Tin Oxide (FTO). The current voltage plots show higher electrooxidation activity of the bimetallic nanostructure of Co/Cu/FTO relative to the bare Co/FTO.


Assuntos
Ligas/química , Técnicas Biossensoriais , Técnicas Eletroquímicas , Glucose/análise , Nanoestruturas/química , Cobalto/química , Cobre/química , Eletrodos , Flúor/química , Humanos , Tamanho da Partícula , Propriedades de Superfície , Compostos de Estanho/química
11.
Food Chem ; 324: 126893, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32344336

RESUMO

An Au patch electrode Ag-SnO2/SiO2/Si MIS capacitive sensor equipped with a microcontroller was designed and developed to sense low concentration (ppb to ppm regime) of volatiles (NH3, TMA, ethanol, and H2S) generated from chicken meat spoilage at room temperature. The quality threshold or the acceptance limit for consumption of chicken meat samples stored at 4 °C, 15 °C and 25 °C using our proposed technique was found to be 105 h, 48 h, and 17 h respectively, highly correlated with TVB-N, TVC, pH and sensory evaluation analysis. When these well established standard methods (TVB-N, TVC and pH analysis) take many hours to complete the analysis involving many complicated steps, our fabricated sensor takes 55 sec to deliver sensing response reflecting the meat spoilage status. The sensor calibrated with our compact technique promises portable and inexpensive onsite rapid and accurate quality assessment of meat spoilage at room temperature.


Assuntos
Gases/análise , Ouro/química , Carne/análise , Semicondutores , Amônia/análise , Animais , Galinhas , Eletrodos , Qualidade dos Alimentos , Sulfeto de Hidrogênio/análise , Concentração de Íons de Hidrogênio , Silício/química , Dióxido de Silício/química , Prata/química , Temperatura , Compostos de Estanho/química
12.
Talanta ; 212: 120797, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-32113559

RESUMO

We report here sensitive photoelectrochemical immunosensing of Staphylococcus aureus (S. aureus) using ZnS-Ag2S/polydopamine (PDA) as a novel photoelectric material and Cu2O as the peroxidase mimic tag. ZnS-Ag2S heterojunctions were prepared on indium tin oxide (ITO) via electrodeposition of ZnS nanoparticles, followed by silver ion exchange. To prepare a PDA/ZnS-Ag2S/ITO, the ZnS-Ag2S/ITO electrode was coated with PDA by self-polymerization of dopamine. The photocurrent of the PDA/ZnS-Ag2S/ITO is 1.55 times that of the ZnS-Ag2S/ITO and 7.87 times that of the ZnS/ITO, indicating a high-performance photoelectric material. A sandwiched-type photoelectrochemical immunosensor was constructed by using PDA/ZnS-Ag2S/ITO as the photoelectrode and Cu2O nanocubes as the labels. Cu2O nanocubes can serve as peroxidase mimic to generate catalytic precipitates on the immunoelectrodes, and both the Cu2O nanocubes and the generated precipitates can decrease the photocurrents of the immunoelectrodes, so a photoelectrochemical immunosensor for detecting S. aureus was constructed, showing a linear range between 10 and 107 CFU mL-1 and a low detection limit of 2 CFU mL-1. Owing to the signal amplification of Cu2O labeling, the sensitivity of the Cu2O-labeled immunosensor is 4 times that of a label-free immunosensor for detecting S. aureus, and the detection limit (2 CFU mL-1) is lower than that of a label-free immunosensor (10 CFU mL-1). This work not only provides a new and efficient photoelectric material but also demonstrated an efficient signal-amplification strategy for photoelectrochemical biosensing.


Assuntos
Cobre/química , Imunoensaio/métodos , Indóis/química , Nanopartículas Metálicas/química , Polímeros/química , Staphylococcus aureus/isolamento & purificação , Anticorpos Imobilizados/imunologia , Técnicas Biossensoriais/métodos , Catálise , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , Eletrodos , Indóis/efeitos da radiação , Luz , Limite de Detecção , Nanopartículas Metálicas/efeitos da radiação , Polímeros/efeitos da radiação , Compostos de Prata/química , Compostos de Prata/efeitos da radiação , Staphylococcus aureus/imunologia , Sulfetos/química , Sulfetos/efeitos da radiação , Compostos de Estanho/química , Compostos de Zinco/química , Compostos de Zinco/efeitos da radiação
13.
Chem Commun (Camb) ; 56(27): 3883-3886, 2020 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-32134083

RESUMO

We developed a label-free homogeneous electrochemical cytosensor for ultrasensitive detection of cancer cells based on multiaptamer-functionalized DNA tetrahedral nanostructures, which avoided expensive labeling and sophisticated immobilization procedures, providing opportunities for precisely detecting cancer cells in clinical applications.


Assuntos
Aptâmeros de Nucleotídeos/química , Técnicas Biossensoriais , DNA/química , Técnicas Eletroquímicas , Nanoestruturas/química , Neoplasias/diagnóstico , Linhagem Celular , Humanos , Compostos de Estanho/química
14.
Anal Bioanal Chem ; 412(8): 1933-1946, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32076788

RESUMO

Biogenic amine biosensors, based on screen-printed carbon electrodes (SPCE) modified with Prussian blue (PB) and indium tin oxide nanoparticles (ITONP), are reported. PB/ITONP-modified SPCE was further modified with diamine oxidase (DAO) or monoamine oxidase (MAO) enzymes to construct the biosensors. The morphology of the modified electrodes was studied by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to enlighten the electrochemical properties of the modified electrodes at each step of biosensor fabrication. Electrode surface composition and experimental conditions were optimized and analytical performance characteristics of the biosensors were studied. Several biogenic amines were tested and both biosensors responded to histamine, putrescine and cadaverine. DAO/ITONP/PB/SPCE biosensor exhibited the highest response to histamine 6.0 × 10-6-6.9 × 10-4 M with a sensitivity of 1.84 µA mM-1. On the other hand, the highest sensitivity was obtained for cadaverine with the MAO/ITONP/PB/SPCE biosensor. The analytical utility of the presented biosensors were illustrated by the determination of cadaverine and histamine in cheese sample.


Assuntos
Amina Oxidase (contendo Cobre)/química , Aminas Biogênicas/análise , Técnicas Eletroquímicas/instrumentação , Eletrodos , Ferrocianetos/química , Nanopartículas Metálicas/química , Monoaminoxidase/química , Compostos de Estanho/química , Técnicas Biossensoriais
15.
Biosens Bioelectron ; 154: 112050, 2020 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-32056957

RESUMO

In this work we discuss a new label-free biosensing device based on indium tin oxide (ITO) overlaid section of a multimode optical fiber fused silica core. The sensor has been used to optical measurements also simultaneously interrogated electrochemically (EC). Due to optimized thickness and optical properties of ITO film, a lossy-mode resonance (LMR) could be observed in the optical domain, where electrical properties of the film allowed for application of the sensor as a working electrode in an EC setup. It has been confirmed that the LMR response depends on optical properties of the external medium, as well as potential applied to the electrode during cyclic voltammetry. After the ITO surface functionalization with amine groups and covalently attached biotin, the device has been applied for label-free biosensing of avidin in both the domains simultaneously. On the example of biotin-avidin detection system it was demonstrated that when avidin concentration increases a decrease in current and increase in LMR wavelength shift were recorded in EC and optical domain, respectively. Both optical and EC responses follow the protein interaction process, and thus can be used as cross-verification of the readouts. Moreover, an extended information has been achieved comparing to solely EC interrogation, i.e., the grafting process of biotin and avidin was directly monitored optically displaying individual steps of an incubation procedure.


Assuntos
Avidina/isolamento & purificação , Técnicas Biossensoriais , Biotina/isolamento & purificação , Técnicas Eletroquímicas , Avidina/química , Biotina/química , Eletrodos , Óptica e Fotônica , Compostos de Estanho/química
16.
Molecules ; 25(3)2020 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-32041230

RESUMO

In this work, layered hybrid composites formed by tin oxide (SnO) nanoparticles synthesized by hydrolysis and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) have been analyzed. Prior to the composite study, both SnO and PEDOT:PSS counterparts were characterized by diverse techniques, such as X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), photoluminescence (PL), atomic force microscopy (AFM), optical absorption and Hall effect measurements. Special attention was given to the study of the stability of the polymer under laser illumination, as well as the analysis of the SnO to SnO2 oxidation assisted by laser irradiation, for which different laser sources and neutral filters were employed. Synergetic effects were observed in the hybrid composite, as the addition of SnO nanoparticles improves the stability and electrical conductivity of the polymer, while the polymeric matrix in which the nanoparticles are embedded hinders formation of SnO2. Finally, the Si passivation behavior of the hybrid composites was studied.


Assuntos
Compostos Bicíclicos Heterocíclicos com Pontes/química , Nanopartículas/química , Polímeros/química , Poliestirenos/química , Compostos de Estanho/química , Condutividade Elétrica , Microscopia de Força Atômica/métodos , Microscopia Eletrônica de Transmissão/métodos
17.
Chemosphere ; 249: 126178, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32087454

RESUMO

Norfloxacin is employed as in veterinary and human medicine against gram-positive and gram-negative bacteria. Due to the ineffective treatment at the wastewater treatment plants it becomes an emergent pollutant. Electro-oxidation appears as an alternative to its effective mineralization. This work compares Norfloxacin electro-oxidation on different anodic materials: two ceramic electrodes (both based on SnO2 + Sb2O3 with and without CuO, named as CuO and BCE, respectively) and a boron doped diamond (BDD). First, the anodes were characterized by cyclic voltammetry, revealing that NOR direct oxidation occurred at 1.30 V vs. Ag/AgCl. The higher the scan rate the higher both the current density and the anodic potential of the peak. This behavior was analyzed using the Randles-Sevcik equation to calculate the Norfloxacin diffusion coefficient in aqueous media, giving a value of D = 7.80 × 10-6 cm2 s-1 at 25 °C), which is close to the predicted value obtained using the Wilke-Chang correlation. The electrolysis experiments showed that both NOR and TOC decay increased with the applied current density, presenting a pseudo-first order kinetic. All the anodes tested achieved more than 90% NOR degradation at each current density. The CuO is not a good alternative to BCE because although it acts as a catalyst during the first use, it is lost from the anode surface in the subsequent uses. According to their oxidizing power, the anodes employed are ordered as follows: BDD > BCE > CuO.


Assuntos
Cobre/química , Norfloxacino/química , Poluentes Químicos da Água/química , Antibacterianos , Antimônio/química , Boro , Cerâmica , Cloretos , Cloro , Diamante , Eletrodos , Eletrólise , Bactérias Gram-Negativas , Bactérias Gram-Positivas , Norfloxacino/análise , Oxirredução , Compostos de Estanho/química , Águas Residuárias , Poluentes Químicos da Água/análise
18.
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
19.
Chem Commun (Camb) ; 56(18): 2691-2694, 2020 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-32051985

RESUMO

A conductive polymer thin film having choline phosphate as the side group was prepared. Quartz crystal microbalance (QCM) was employed to evaluate the adsorption of the model protein, bovine serum albumin (BSA), on the films deposited on indium tin oxide (ITO) electrodes. Cell adsorption on the film was evaluated by a fibroblast NIH3T3.


Assuntos
Fosforilcolina/química , Polímeros/química , Soroalbumina Bovina/química , Adsorção , Animais , Bovinos , Condutividade Elétrica , Eletrodos , Camundongos , Estrutura Molecular , Células NIH 3T3 , Imagem Óptica , Polímeros/síntese química , Técnicas de Microbalança de Cristal de Quartzo , Propriedades de Superfície , Compostos de Estanho/química
20.
Talanta ; 210: 120671, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31987184

RESUMO

The pH dependent size control of Bovine Serum Albumin (BSA) and its biosensing potential with Tin Oxide and Tin Sulfide Quantum Dots (SnO2/SnS2 QDs) is reported. The role of disulfide bond cleavage in BSA at acidic and circumneutral pH conditions (3 and 7.2) with sodium borohydride as reducing agent, makes changes in its stability, prone to aggregation and microcapsule formation respectively. Here, the structural reduction in BSA (r-BSA2) at pH 7.2 probed more -OH groups eventually creating adhesive surfaces for SnO2/SnS2 QDs due to electrostatic and hydrophobic forces, thus avoids the aggregation of SnO2/SnS2 QDs in composite formation. The accumulation of more active sites in SnO2/SnS2 QDs decorated r-BSA2 (SnO2/SnS2@r-BSA2) nanobiocomposite favored suitable orientation for Melatonin (Mel) detection. The designed SnO2/SnS2@r-BSA2 nanobiocomposite over the screen printing electrode exhibited electrochemical detection capabilities for the selective and sensitive recognition of Mel in the linear range of 0.2-1000 µM with a lower detection limit of 16 nM. Additionally, the fabricated biosensor was successfully validated for the determination of Mel in real samples.


Assuntos
Técnicas Biossensoriais , Soroalbumina Bovina/química , Sulfetos/química , Compostos de Estanho/química , Adsorção , Animais , Bovinos , Concentração de Íons de Hidrogênio , Oxirredução , Tamanho da Partícula , Propriedades de Superfície
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