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1.
Sci Rep ; 10(1): 13309, 2020 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-32764617

RESUMO

Research efforts towards developing near-infrared (NIR) therapeutics to activate the proliferation of human keratinocytes and collagen synthesis in the skin microenvironment have been minimal, and the subject has not been fully explored. Herein, we describe the novel synthesis Ag2S nanoparticles (NPs) by using a sonochemical method and reveal the effects of NIR irradiation on the enhancement of the production of collagen through NIR-emitting Ag2S NPs. We also synthesized Li-doped Ag2S NPs that exhibited significantly increased emission intensity because of their enhanced absorption ability in the UV-NIR region. Both Ag2S and Li-doped Ag2S NPs activated the proliferation of HaCaT (human keratinocyte) and HDF (human dermal fibroblast) cells with no effect on cell morphology. While Ag2S NPs upregulated TIMP1 by only twofold in HaCaT cells and TGF-ß1 by only fourfold in HDF cells, Li-doped Ag2S NPs upregulated TGF-ß1 by tenfold, TIMP1 by 26-fold, and COL1A1 by 18-fold in HaCaT cells and upregulated TGF-ß1 by fivefold and COL1A1 by fourfold in HDF cells. Furthermore, Ag2S NPs activated TGF-ß1 signaling by increasing the phosphorylation of Smad2 and Smad3. The degree of activation was notably higher in cells treated with Li-doped Ag2S NPs, mainly caused by the higher PL intensity from Li-doped Ag2S NPs. Ag2S NPs NIR activates cell proliferation and collagen synthesis in skin keratinocytes and HDF cells, which can be applied to clinical light therapy and the development of anti-wrinkle agents for cosmetics.


Assuntos
Colágeno/biossíntese , Raios Infravermelhos , Nanopartículas/química , Transdução de Sinais/efeitos dos fármacos , Compostos de Prata/química , Compostos de Prata/farmacologia , Fator de Crescimento Transformador beta/metabolismo , Humanos , Queratinócitos/citologia , Queratinócitos/efeitos dos fármacos , Queratinócitos/metabolismo
2.
J Vis Exp ; (161)2020 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-32716373

RESUMO

This paper aims to present a protocol to form smooth and well-controlled films of silver/silver chloride (Ag/AgCl) with designated coverage on top of thin film silver electrodes. Thin film silver electrodes sized 80 µm x 80 µm and 160 µm x 160 µm were sputtered on quartz wafers with a chromium/gold (Cr/Au) layer for adhesion. After passivation, polishing and cathodic cleaning processes, the electrodes underwent galvanostatic oxidation with consideration of Faraday's Law of Electrolysis to form smooth layers of AgCl with a designated degree of coverage on top of the silver electrode. This protocol is validated by inspection of scanning electron microscope (SEM) images of the surface of the fabricated Ag/AgCl thin film electrodes, which highlights the functionality and performance of the protocol. Sub-optimally fabricated electrodes are fabricated as well for comparison. This protocol can be widely used to fabricate Ag/AgCl electrodes with specific impedance requirements (e.g., probing electrodes for impedance sensing applications like impedance flow cytometry and interdigitated electrode arrays).


Assuntos
Eletrodos , Compostos de Prata/química , Prata/química
3.
Photochem Photobiol Sci ; 19(7): 943-955, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32478777

RESUMO

In this work, a high-surface-area dual inorganic molecularly imprinted (DIMI) Bi2WO6/CuO/Ag2O photocatalyst was developed for the selective photocatalytic degradation of methyl green (MG) and auramine O (AO) dyes as target pollutants. The DIMI-Bi2WO6/CuO/Ag2O heterojunction was synthesized by a sonochemically assisted sol-gel method by coating a layer of molecularly imprinted Ag2O/CuO on the surface of Bi2WO6 nanocubes with MG and AO as the templates. This was followed by calcination for the removal of target molecules and annealing for Ag/Cu oxide preparation. This novel photocatalyst was prepared to overcome the challenge of the co-existing non-target molecules, which has limited the photocatalytic degradation performance. The surface DIMI sites could act as surface defects for accelerating the separation of photogenerated holes and electrons, which led to the increased generation of OH radicals. Moreover, the DIMI sites had increased binding affinity toward MG and AO via the formation of multiple H bonds and electrostatic bonds, which were confirmed by FTIR spectroscopy, PL and EIS studies. The surface DIMI sites led to the increased adsorption and improved local concentration of MG and AO on Bi2WO6/CuO/Ag2O. Consequently, the heterojunction properties of the final DIMI product accelerated the transfer and separation of photogenerated carriers. The high binding affinity of the DIMI sites to MG and AO confirmed the selective recognition, which was tested in the presence of coexisting pollutant dyes. The other characterizations confirmed the successful fabrication and high photocatalytic activity of the high-surface-area DIMI-Bi2WO6/CuO/Ag2O heterostructured composite. In general, the superior interfacial electronic interactions, high migration efficiency of photoinduced charge carriers, and strong visible light absorption of the prepared photocatalyst resulted in good photocatalytic performance.


Assuntos
Benzofenoneídio/química , Corantes/química , Verde de Metila/química , Impressão Molecular , Nanopartículas/química , Poluentes Químicos da Água/química , Bismuto/química , Catálise , Cobre/química , Luz , Estrutura Molecular , Óxidos/química , Tamanho da Partícula , Processos Fotoquímicos , Compostos de Prata/química , Propriedades de Superfície , Compostos de Tungstênio/química
4.
Anal Chim Acta ; 1114: 29-41, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32359512

RESUMO

This work focused on the combination of CdTe and AgInS2 quantum dots in a dual-emission nanoprobe for the simultaneous determination of folic acid and Fe(II) in pharmaceutical formulations. The surface chemistry of the used QDs was amended with suitable capping ligands to obtain appropriate reactivity in terms of selectivity and sensitivity towards the target analytes. The implementation of PL-based sensing schemes combining multiple QDs of different nature, excited at the same wavelength and emitting at different ones, allowed to obtain a specific analyte-response profile. The first-order fluorescence data obtained from the whole emission spectra of the CdTe/AgInS2 combined nanoprobe upon interaction with folic acid and Fe(II) were processed by using chemometric tools, namely partial least-squares (PLS) and artificial neural network (ANN). This enabled to circumvent the selectivity issues commonly associated with the use of QDs prone to indiscriminate interaction with multiple species, which impair reliable and accurate quantification in complex matrices samples. ANN demonstrated to be the most efficient chemometric model for the simultaneous determination of both analytes in binary mixtures and pharmaceutical formulations due to the non-linear relationship between analyte concentration and fluorescence data that it could handle. The R2P and SEP% obtained for both analytes quantification in pharmaceutical formulations through ANN modelling ranged from 0.92 to 0.99 and 5.7-9.1%, respectively. The obtained results revealed that the developed approach is able to quantify, with high reliability and accuracy, more than one analyte in complex mixtures and real samples with pharmaceutical interest.


Assuntos
Corantes Fluorescentes/química , Ácido Fólico/análise , Ferro/análise , Redes Neurais de Computação , Compostos de Cádmio/química , Índio/química , Medições Luminescentes , Processos Fotoquímicos , Compostos de Prata/química , Enxofre/química , Telúrio/química
5.
J Photochem Photobiol B ; 207: 111882, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32361282

RESUMO

Silver sulfide­magnesium oxide/graphene oxide (Ag2S-MgO/GO) nanocomposite was prepared via sol-gel/ultrasound method to modify the photo-degradation performance for rhodamine B decontamination under visible and UV light. Analytical studies were performed to distinguish the properties such as structure, morphology, and elements of prepared materials. The average crystallite size of MgO, Ag2S-MgO and Ag2S-MgO/GO is distinguished to be 24.2, 29.3 and 33.1 nm, respectively. The Band gap MgO, Ag2S-MgO and Ag2S-MgO/GO is 4.08, 3.25 and 2.82 eV, respectively. Ag2S-MgO/GO nanocomposites illustrated the highest photo-degradation rate of rhodamine B (RhB) under UV light (98.8%) and visible light (64.8%) during in 60 min. In this project, the process parameter of pH and time were investigated for RhB degradation activity influence. The suggested mechanisms for the enhanced photo-degradation of RhB by Ag2S-MgO/GO nanocomposites under light irradiation due to enhanced charge transfer efficiency via decreasing band gap amount; reduced e-/h+ recombination of MgO with the Ag2S crystal and an enhanced removal efficiency with the supported on graphene oxide. Examination of the antibacterial and antifungal properties of the prepared nano-materials were conducted with Bacillus vallismortis, Escherichia coli, Aspergillus flavus and Trichoderma viride. The beneficial antibacterial and antifungal performance of the Ag2S-MgO/GO nanocomposites was further tested by a great reduction in the number of bacteria and fungi medium with the addition of the Ag2S-MgO/GO nanocomposites.


Assuntos
Anti-Infecciosos/química , Grafite/química , Óxido de Magnésio/química , Nanocompostos/química , Compostos de Prata/química , Bacillus/efeitos dos fármacos , Catálise , Escherichia coli/efeitos dos fármacos , Luz , Processos Fotoquímicos , Rodaminas/química , Relação Estrutura-Atividade , Propriedades de Superfície , Fatores de Tempo
6.
Nat Commun ; 11(1): 2569, 2020 05 22.
Artigo em Inglês | MEDLINE | ID: mdl-32444828

RESUMO

Methods for direct C-H trifluoromethoxylation of arenes and heteroarenes are rare, despite the importance of trifluoromethoxylated compounds for pharmaceuticals, agrochemicals, and material sciences. Especially selective C-H trifluoromethoxylation of pyridines remains a formidable challenge. Here we show a general late-stage C-H trifluoromethoxylation of arenes and heteroarenes as limiting reagent with trifluoromethoxide anion. The reaction is mediated by silver salts under mild reaction conditions, exhibiting broad substrate scope and wide functional-group compatibility. In addition, ortho-position selective C-H trifluoromethoxylation of pyridines is observed. The method is not only applicable to the gram-scale synthesis of trifluoromethoxylated products but also allows efficient late-stage C-H trifluoromethoxylation of marketed small-molecule drugs, common pharmacophores and natural products.


Assuntos
Hidrocarbonetos Fluorados/química , Técnicas de Química Sintética , Piridinas/química , Compostos de Prata/química
7.
J Colloid Interface Sci ; 575: 183-193, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32361235

RESUMO

Numerous nanosized photocatalysts have been demonstrated to treat antibiotic solutions efficiently in beakers, but plenty of antibiotics have been discharged to the flowing rivers. For photocatalytically degrading the flowing antibiotic wastewater, the prerequisite is to develop flexible large-scale filter-membrane with high photocatalytic activity. To solve this issue, with carbon fiber (CF) cloth as a flexible porous substrate, herein we have reported the in-situ growth of BiOBr/Ag3PO4 heterostructures. BiOBr nanosheets (thickness: ~10 nm, diameter: 0.5-1 µm) and Ag3PO4 particles (size: 50-200 nm) are synthesized on CF cloth successively via a solvothermal-chemical deposition two-step strategy. CF/BiOBr/Ag3PO4 cloth displays excellent visible photoabsorption (edge: ~520 nm). Under visible-light illumination, CF/BiOBr/Ag3PO4 cloth (4 × 4 cm2) could degrade ~90.0% tetracycline hydrochloride (TCH) as a model of antibiotics in 30 min in a beaker. Especially, CF/BiOBr/Ag3PO4 cloth can be used as the filter-membrane to construct multiple photocatalytic-setup for degrading the flowing antibiotic wastewater. The removal efficiency of TCH goes up from 12.8% at the first grade to 89.6% at the sixth grade. Furthermore, the photocatalytic mechanism of CF/BiOBr/Ag3PO4 cloth and the possible decomposition pathway of TCH have been proposed based on simulation and experiment results. Therefore, the present work provides some insight for developing flexible filter-membrane-shaped photocatalysts for degrading the flowing wastewater.


Assuntos
Antibacterianos/química , Bismuto/química , Fibra de Carbono/química , Fosfatos/química , Compostos de Prata/química , Águas Residuárias/química , Purificação da Água , Antibacterianos/síntese química , Catálise , Estrutura Molecular , Tamanho da Partícula , Processos Fotoquímicos , Propriedades de Superfície , Microbiologia da Água
8.
Int J Nanomedicine ; 15: 2829-2839, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32368057

RESUMO

Objective: To investigate the remineralizing and staining effects of sodium fluoride (NaF) solution with polyethylene glycol-coated silver nanoparticles (PEG-AgNPs) on artificial dentine caries. Materials and Methods: Demineralized human dentine blocks were allocated to three groups. The blocks in group 1 underwent a topical application of a 12% silver diamine fluoride (SDF, 14,150 ppm fluoride) solution. The blocks in group 2 received a topical application of a 2.5% NaF (11,310 ppm fluoride) with PEG-AgNPs (400 ppm silver). The blocks in group 3 received deionized water. All blocks were subjected to pH cycling for 8 days. The surface morphology and cross-sectional features were investigated using scanning electron microscopy (SEM). The color parameters, crystal characteristics, lesion depth, and collagen degradation of the blocks were assessed using digital spectrophotometry, X-ray diffraction (XRD), micro-computed tomography, and spectrophotometry with a hydroxyproline assay, respectively. Results: The SEM showed that dentine collagen was exposed in group 3 but not in groups 1 and 2. The mean lesion depths in groups 1 to 3 were 118±7 µm, 121±14 µm, and 339±20 µm, respectively (groups1,2<3; p<0.001). The data indicated that fluoridated PEG-AgNPs introduced no significant color effect on dentine, but SDF caused distinct discoloration. The XRD indicated that silver chloride was formed in group 1, and fluorapatite was detected in groups 1 and 2. The concentration of hydroxyproline liberated from collagen was significantly less in groups 1 and 2 than in group 3. Conclusion: The use of NaF solution with PEG-AgNPs can remineralize artificial dentine caries and inhibit collagen degradation without causing significant tooth staining.


Assuntos
Cárie Dentária/tratamento farmacológico , Dentina/efeitos dos fármacos , Nanopartículas Metálicas/uso terapêutico , Fluoreto de Sódio/farmacologia , Remineralização Dentária/métodos , Colágeno , Cor , Dentina/metabolismo , Dentina/patologia , Fluoretos/farmacologia , Fluoretos Tópicos/química , Fluoretos Tópicos/farmacologia , Humanos , Hidroxiprolina/metabolismo , Nanopartículas Metálicas/administração & dosagem , Nanopartículas Metálicas/química , Microscopia Eletrônica de Varredura , Dente Serotino/efeitos dos fármacos , Dente Serotino/patologia , Dente Serotino/ultraestrutura , Polietilenoglicóis/química , Compostos de Amônio Quaternário/química , Compostos de Amônio Quaternário/farmacologia , Prata , Compostos de Prata/química , Compostos de Prata/farmacologia , Fluoreto de Sódio/administração & dosagem , Difração de Raios X , Microtomografia por Raio-X
9.
Mater Sci Eng C Mater Biol Appl ; 111: 110779, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32279761

RESUMO

Development of bone graft substitutes with appropriate integration of mechanical, biodegradable, and biofunctional properties, which promote bone formation while simultaneously preventing implant-associated infections, remains a great challenge. Herein we designed and synthesized a brushite/Ag3PO4-coated Mg-Nd-Zn-Zr scaffolds through chemical solution deposition of a composite coating onto the fluorinated Mg-based scaffolds generated with template replication method. The coated Mg-based open-porous scaffolds exhibit hierarchically-structured surface with cube-shaped Ag3PO4 nanoparticles uniformly distributed on top of microsized brushite grains. Immersion test reveals that the initial degradation rate of the coated scaffolds could be reduced by ~81% compared to the original scaffolds. The mean corrosion rate in 4 weeks falls into 0.10-0.15 mm/year to meet clinical requirements. The compatibility and ALP activity of cells grown in the extracts from the coated Mg-based scaffolds were increased compared with Ti control and original scaffolds, mainly due to the favorable microenvironment generated by Mg biodegradation. Besides, the coated Mg-based scaffold demonstrated potent antimicrobial activity via the synergistic actions of alkaline degradation products of Mg and the Ag species in the coating, achieving >99.5% antibacterial rate against both gram-positive and gram-negative bacteria with relatively low silver content. Taken together, this study presents a new candidate of brushite/Ag3PO4-coated Mg-based scaffold with appropriate degradation characteristics, cytocompatibility, and antimicrobial activities for bone tissue engineering applications.


Assuntos
Anti-Infecciosos/química , Materiais Biocompatíveis/química , Fosfatos de Cálcio/química , Magnésio/química , Fosfatos/química , Compostos de Prata/química , Ligas/química , Animais , Anti-Infecciosos/metabolismo , Anti-Infecciosos/farmacologia , Materiais Biocompatíveis/metabolismo , Materiais Biocompatíveis/farmacologia , Adesão Celular/efeitos dos fármacos , Linhagem Celular , Movimento Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Corrosão , Camundongos , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus epidermidis/efeitos dos fármacos
10.
Dalton Trans ; 49(16): 5205-5218, 2020 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-32236268

RESUMO

A number of porous g-C3N4 nanosheet/Ag3PO4/NCDs (PCNNS/AP/NCDs) with little amounts of Ag3PO4 were synthesized via an in situ sedimentation-calcination method. The PCNNS/AP/NCDs photocatalyst exhibited excellent photocatalytic performance for the photocatalytic degradation of tetracycline (TC) under visible light irradiation at a removal rate of 90.5% in 40 min. The study of the reaction kinetics of the as-prepared samples was in accordance with the pseudo-second-order kinetics, with the correlation coefficient (R2) being greater than 0.9776. Meanwhile, the photocatalyst was capable of degrading ciprofloxacin (CIP), and showed good performance even under actual water conditions with natural sunlight irradiation, indicating that the photocatalyst has wide practical applications. In addition, the photocatalytic performance and the XRD and FTIR spectra showed no obvious changes even after four photocatalytic degradation cycles, which revealed the high stability of the PCNNS/AP/NCDs photocatalyst. Furthermore, the possible degradation pathways of TC and the possible Z-scheme mechanism were proposed with ˙O2- and h+ as the main active species contributing to photocatalytic degradation. The results provide a novel insight into the fabrication of Z-scheme PCNNS/AP/NCDs and introduce them as an efficient visible-light-responsive photocatalyst for use in practical applications.


Assuntos
Antibacterianos/isolamento & purificação , Ciprofloxacino/isolamento & purificação , Grafite/química , Nanocompostos/química , Compostos de Nitrogênio/química , Fosfatos/química , Pontos Quânticos/química , Compostos de Prata/química , Antibacterianos/química , Carbono/química , Catálise , Ciprofloxacino/química , Cinética , Tamanho da Partícula , Processos Fotoquímicos , Propriedades de Superfície
11.
ACS Appl Mater Interfaces ; 12(14): 17091-17099, 2020 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-32154701

RESUMO

Silver compounds have been used extensively for wound healing because of their antimicrobial properties, but high concentrations of silver are toxic to mammalian cells. We designed a peptide that binds silver and releases only small amounts of this ion over time, therefore overcoming the problem of silver toxicity. Silver binding was achieved through incorporation of an unnatural amino acid, 3'-pyridyl alanine (3'-PyA), into the peptide sequence. Upon the addition of silver ions, the peptide adopts a beta-sheet secondary structure and self-assembles into a strong hydrogel as characterized by rheology, circular dichroism, and transmission electron microscopy. We show that the resulting hydrogel kills Escherichia coli and Staphylococcus aureus but is not toxic to fibroblasts and could be used for wound healing. The amount of Ag(I) released by hydrogels into the solution is less than 4% and this low amount of Ag(I) does not change in the pH range 6-8. These studies provide an initial indication for use of the designed hydrogel as injectable, antimicrobial wound dressing.


Assuntos
Infecções Bacterianas/tratamento farmacológico , Hidrogéis/farmacologia , Nanopartículas Metálicas/química , Peptídeos/química , Anti-Infecciosos/química , Anti-Infecciosos/farmacologia , Infecções Bacterianas/microbiologia , Escherichia coli/efeitos dos fármacos , Escherichia coli/patogenicidade , Humanos , Hidrogéis/química , Peptídeos/farmacologia , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/patogenicidade , Prata/química , Compostos de Prata/química , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/patogenicidade , Cicatrização/efeitos dos fármacos
12.
Part Fibre Toxicol ; 17(1): 11, 2020 03 10.
Artigo em Inglês | MEDLINE | ID: mdl-32156294

RESUMO

BACKGROUND: Silver nanoparticles (AgNPs) are used extensively in various consumer products because of their antimicrobial potential. This requires insight in their potential hazards and risks including adverse effects during pregnancy on the developing fetus. Using a combination of the BeWo b30 placental transport model and the mouse embryonic stem cell test (EST), we investigated the capability of pristine AgNPs with different surface chemistries and aged AgNPs (silver sulfide (Ag2S) NPs) to cross the placental barrier and induce developmental toxicity. The uptake/association and transport of AgNPs through the BeWo b30 was characterized using ICP-MS and single particle (sp)ICP-MS at different time points. The developmental toxicity of the AgNPs was investigated by characterizing their potential to inhibit the differentiation of mouse embryonic stem cells (mESCs) into beating cardiomyocytes. RESULTS: The AgNPs are able to cross the BeWo b30 cell layer to a level that was limited and dependent on their surface chemistry. In the EST, no in vitro developmental toxicity was observed as the effects on differentiation of the mESCs were only detected at cytotoxic concentrations. The aged AgNPs were significantly less cytotoxic, less bioavailable and did not induce developmental toxicity. CONCLUSIONS: Pristine AgNPs are capable to cross the placental barrier to an extent that is influenced by their surface chemistry and that this transport is likely low but not negligible. Next to that, the tested AgNPs have low intrinsic potencies for developmental toxicity. The combination of the BeWo b30 model with the EST is of added value in developmental toxicity screening and prioritization of AgNPs.


Assuntos
Diferenciação Celular/efeitos dos fármacos , Células-Tronco Embrionárias/efeitos dos fármacos , Nanopartículas Metálicas/toxicidade , Miócitos Cardíacos/efeitos dos fármacos , Placenta/efeitos dos fármacos , Compostos de Prata/toxicidade , Prata/toxicidade , Animais , Transporte Biológico , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Feminino , Humanos , Nanopartículas Metálicas/química , Camundongos , Modelos Biológicos , Miócitos Cardíacos/metabolismo , Tamanho da Partícula , Placenta/metabolismo , Gravidez , Prata/química , Compostos de Prata/química , Propriedades de Superfície
13.
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
14.
Sensors (Basel) ; 20(5)2020 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-32106461

RESUMO

We demonstrated a newly developed Ag/AgCl reference electrode- with a valve-actuator for two years or longer rumen pH monitoring. Previous studies on pH sensors reported that the short lifetime of Ag/AgCl reference electrodes is caused by an outflow of internal electrolyte. We introduced a valve-actuator into a liquid junction to reduce the outflow by intermittent measurement. The results indicated that the potential change when switching the liquid junction was less than 0.5 mV and its response time was less than 0.083 s. In the 24-h potential measurement with the valve-actuator-integrated reference electrode (VAIRE), the valve was actuated once every hour, and the standard deviation of the potential was 0.29 mV. The lifetime of the VAIRE was estimated at 2.0 years calculating from an electrolyte outflow, which is significantly longer than that of conventional reference electrodes. A pH sensor using the VAIRE was estimated to operate for 2.0 years with the pH error ≤0.1, which meets the requirement of cows' rumen pH monitoring.


Assuntos
Técnicas Biossensoriais/instrumentação , Rúmen/fisiologia , Animais , Bovinos , Impedância Elétrica , Eletrodos , Eletrólitos/química , Concentração de Íons de Hidrogênio , Processamento de Imagem Assistida por Computador , Padrões de Referência , Ligas de Memória da Forma , Prata/química , Compostos de Prata/química
15.
BMC Oral Health ; 20(1): 40, 2020 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-32024501

RESUMO

BACKGROUND: Silver diamine fluoride (SDF) solution gains increasing popularity in arresting dentine caries in clinical practice. The aim of this systematic review was to summarize the findings from laboratory studies on the influence of SDF application on the bond strength of dentine to various adhesives and to glass ionomer cements (GICs). METHODS: Two independent reviewers conducted a literature search in the databases Medline, Ovid, PubMed and Web of Science until 15th August 2019 using the search keywords ['bond strength'] AND ['silver diamine fluoride' OR 'silver diammine fluoride' OR 'SDF' OR 'silver fluoride' OR 'diamine silver fluoride']. Articles investigating the effect of SDF application on the bond strength of dentine to various adhesives and to GICs were included in this review. Information on how SDF application influenced the bond strength was extracted from the included articles. Besides, related information, e.g. test method of bond strength, concentration and brand of SDF, type of adhesive system and GIC, testing dental substrate, protocol of specimen preparation, and failure mode was also reviewed. RESULTS: A total of 13 articles were included in this review, with 8 and 6 studies investigating the effect of SDF application on the bond strength of dentine to various adhesives and to GICs, respectively. Sound dentine as well as demineralized dentine created by chemical methods, e.g. immersing in a demineralizing solution, was commonly adopted as the testing dental substrate. The microtensile bond strength (mTBS) test was the predominant method employed. However, the bond strength values had large variations among studies, ranging from <10 to 162 Mpa. Regarding the bond strength to different adhesives, 4 studies indicated that SDF application followed by rinsing with water had no significant influence. However, another 4 studies reported reduced bond strength after SDF application. Regarding the bond strength to GICs, 4 studies concluded that SDF application had no adverse impact on the bond strength. CONCLUSIONS: No solid conclusion can be drawn on the effect of SDF application on the bond strength of dentine to adhesives and to GICs due to the high degree of variation of the included studies.


Assuntos
Colagem Dentária , Cimentos Dentários , Dentina/metabolismo , Cimentos de Ionômeros de Vidro/química , Compostos de Amônio Quaternário/farmacologia , Compostos de Prata/química , Fluoretos Tópicos/farmacologia , Humanos , Compostos de Prata/farmacologia , Estresse Mecânico
16.
Nanoscale ; 12(9): 5678-5684, 2020 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-32101213

RESUMO

Near-infrared-II (NIR-II, 1000-1700 nm) bioimaging features high penetration depth and high spatio-temporal resolution compared to traditional fluorescence imaging, but the key is to develop stable and biocompatible NIR-II fluorophores suitable for in vivo applications. Silver sulfide quantum dots (Ag2S QDs) have been demonstrated to be excellent for in vivo NIR-II imaging with unique optical properties and decent biocompatibility, but they often require complex post modifications for in vivo applications. Herein we demonstrate a facile one-pot strategy to synthesize PEGylated dendrimer-encapsulated Ag2S QDs useful for in vivo NIR-II imaging. Silver ions were first loaded into the core of an acylthiourea-functionalized dendrimer (PEG-PATU) through coordination between silver ions and acylthiourea groups, followed by the addition of sodium sulfide to form Ag2S QDs in situ. The resulting PEG-PATU Ag2S QDs exhibit excellent NIR-II fluorescence signals, and thus could be used for high efficiency labelling and tracking of A549 cancer cell mobility in vivo and real time visualization of the vast circulatory network of a mouse.


Assuntos
Dendrímeros/química , Pontos Quânticos/química , Compostos de Prata/química , Espectroscopia de Luz Próxima ao Infravermelho/métodos , Células A549 , Animais , Sobrevivência Celular/efeitos dos fármacos , Desenho de Fármacos , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Neoplasias/diagnóstico por imagem , Polietilenoglicóis/química , Pontos Quânticos/metabolismo , Pontos Quânticos/toxicidade , Espécies Reativas de Oxigênio/metabolismo , Transplante Heterólogo
17.
Mikrochim Acta ; 187(3): 169, 2020 02 14.
Artigo em Inglês | MEDLINE | ID: mdl-32060641

RESUMO

In this work, novel silver sulphide quantum dots (Ag2S QD) are electrochemically quantified for the first time. The method is based on the electrochemical reduction of Ag+ to Ag0 at -0.3 V on screen-printed carbon electrodes (SPCEs), followed by anodic stripping voltammetric oxidation that gives a peak of currents at +0.06 V which represents the analytical signal. The optimized methodology allows the quantification of water-stabilized Ag2S QD in the range of approximately 2 × 109-2 × 1012 QD·mL-1 with a good reproducibility (RSD: 5%). Moreover, as proof-of-concept of relevant biosensing application, Ag2S QD are evaluated as tags for Escherichia coli (E. coli) bacteria determination. Bacteria tagged with QD are separated by centrifugation from the sample solution and placed on the SPCE surface for quantitative analysis. The effect of two different Ag2S QD surface coating/stabilizing agents on both the voltammetric response and the bacteria sensing is also evaluated. 3-mercaptopropionic acid (3-MPA) is studied as model of short length coating ligand with no affinity for the bacteria, while boronic acid (BA) is evaluated as longer length ligand with chemical affinity for the polysaccharides present in the peptidoglycan layer on the bacteria cells surface. The biosensing system allows to detect bacteria in the range 10-1-103 bacteria·mL-1 with a limit of detection as low as 1 bacteria·mL-1. This methodology is a promising proof-of-concept alternative to traditional laboratory-based tests, with good sensitivity and short time and low cost of analysis. Graphical abstractNovel silver sulphide quantum dots (Ag2S QD) are electrochemically quantified for the first time. Moreover, Ag2S QD are evaluated as tags for Escherichia coli bacteria determination. The effect of two different QD surface coating ligands is also evaluated.


Assuntos
Bactérias/patogenicidade , Técnicas Eletroquímicas/métodos , Pontos Quânticos/química , Compostos de Prata/química , Ligantes
18.
J Agric Food Chem ; 68(7): 2124-2131, 2020 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-31985223

RESUMO

Lignin acylated with acetate and/or p-coumarate is common in many herbaceous plants. Herein, the biomimetic oxidation of γ-acylated monolignols with Ag2O was studied to understand the effect of γ-acyl groups on monolignol polymerization. The oxidation of sinapyl acetate gave γ-acylated and α-acylated ß-O-4 dimers in 71 and 9.5% yields, respectively. The oxidation of sinapyl p-coumarate produced γ-acylated ß-O-4 and γ-acylated tetralin ß-ß dimers in 53 and 16% yields, respectively. Only the sinapyl alcohol moiety in sinapyl p-coumarate reacted, and the p-coumarate moiety remained unchanged, suggesting that p-coumaric acid is not incorporated into the lignin backbone in the acylated lignins. All of the γ-acylated monolignols used in this study produced the γ-acylated ß-O-4 dimers, which suggests that the γ-acylated monolignols act as lignin monomers. The relatively high yields of the ß-O-4 dimers indicate that Ag2O oxidation of the monolignols can be used as an easy method for synthesizing the ß-O-4 dimer model compounds.


Assuntos
Ácidos Cumáricos/química , Dioxanos/química , Lignina/química , Óxidos/química , Compostos de Prata/química , Acetatos/química , Biomimética , Oxirredução
19.
Chem Commun (Camb) ; 56(15): 2300-2303, 2020 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-31989132

RESUMO

A novel signal self-enhancement photoelectrochemical immuno-sensor has been developed based on the curing of sacrificial agent SO32- coated-Au NPs sensitizing Ag2S/CuS/α-Fe2O3 n-p-n hetero-structure films for the first time. This strategy has acquired high sensitivity and low background without addition of a sacrificial agent in solution in the detection of prostate antigen.


Assuntos
Técnicas Biossensoriais , Cobre/química , Técnicas Eletroquímicas , Compostos Férricos/química , Imunoensaio , Antígeno Prostático Específico/análise , Compostos de Prata/química , Humanos , Tamanho da Partícula , Processos Fotoquímicos , Soluções , Propriedades de Superfície
20.
Mikrochim Acta ; 187(2): 104, 2020 01 08.
Artigo em Inglês | MEDLINE | ID: mdl-31912290

RESUMO

Authors report on a new fluoro-graphene-plasmonic nanohybrid aptamer-based fluorescent nanoprobe for cocaine. To construct the nanoprobe, newly synthesized glutathione-capped ZnS/Ag2Se quantum dots (QDs) were first conjugated to graphene oxide (GO) to form a QD-GO nanocomposite. The binding interaction resulted in a fluorescence turn-ON. Thereafter, cetyltrimethylammonium bromide (CTAB)-gold nanoparticles (AuNPs) were directly adsorbed on the QD-GO nanocomposite to form a novel QD-GO-CTAB-AuNP nanohybrid assembly that resulted in a fluorescence turn-OFF. Streptavidin (strep) was then adsorbed on the QDs-GO-CTAB-AuNP nanohybrid assembly which allowed binding to a biotinylated MNS 4.1 anticocaine DNA aptamer (B) receptor. The addition of cocaine into the strep-B-QDs-GO-CTAB-AuNP aptamer nanoprobe system aided affinity to the aptamer receptor and in turn turned on the fluorescence of the nanoprobe in a concentration-dependent manner. Under optimum experimental conditions, we found the strep-B-QD-GO-CTAB-AuNP to be far superior in its sensitivity to cocaine than the tested strep-B-QDs (no GO and CTAB-AuNPs), strep-B-QD-CTAB-AuNP (no GO) and strep-B-QD-GO (no CTAB-AuNP). In addition, the investigation of localized surface plasmon resonance (LSPR) amplified signal from tested plasmonic NPs shows that CTAB-AuNPs was far superior in amplifying the fluorescence signal of the nanoprobe. A detection limit of 4.6 nM (1.56 ng.mL-1), rapid response time (~2 min) and excellent selectivity against other drugs, substances and cocaine metabolites was achieved. The strep-B-QD-GO-CTAB-AuNP aptamer-based fluorescent nanoprobe was successfully applied for the determination of cocaine in seized adulterated cocaine samples. Graphical abstractSchematic representation of the streptavidin-biotin-quantum dot-graphene oxide-cetyltrimethylammonium bromide-gold nanoparticle aptamer-based fluorescent nanoprobe for cocaine.


Assuntos
Aptâmeros de Nucleotídeos/química , Técnicas Biossensoriais/métodos , Cocaína/análise , Pontos Quânticos/química , Compostos de Selênio/química , Compostos de Prata/química , Sulfetos/química , Compostos de Zinco/química , Inibidores da Captação de Dopamina/análise , Contaminação de Medicamentos , Corantes Fluorescentes/química , Glutationa/química , Ouro/química , Grafite/química , Drogas Ilícitas/análise , Limite de Detecção , Nanopartículas Metálicas/química , Nanocompostos/química , Espectrometria de Fluorescência/métodos
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