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1.
Nat Commun ; 11(1): 4899, 2020 09 29.
Artigo em Inglês | MEDLINE | ID: mdl-32994420

RESUMO

Chemical synthesis of amino acids from renewable sources is an alternative route to the current processes based on fermentation. Here, we report visible-light-driven amination of biomass-derived α-hydroxyl acids and glucose into amino acids using NH3 at 50 °C. Ultrathin CdS nanosheets are identified as an efficient and stable catalyst, exhibiting an order of magnitude higher activity towards alanine production from lactic acid compared to commercial CdS as well as CdS nanoobjects bearing other morphologies. Its unique catalytic property is attributed mainly to the preferential formation of oxygen-centered radicals to promote α-hydroxyl acids conversion to α-keto acids, and partially to the poor H2 evolution which is an undesired side reaction. Encouragingly, a number of amino acids are prepared using the current protocol, and one-pot photocatalytic conversion of glucose to alanine is also achieved. This work offers an effective catalytic system for amino acid synthesis from biomass feedstocks under mild conditions.


Assuntos
Alanina/síntese química , Compostos de Cádmio/química , Sulfetos/química , Alanina/química , Biomassa , Catálise/efeitos da radiação , Hidrogênio/química , Ácido Láctico/química , Luz , Modelos Químicos , Oxigênio/química
2.
Bull Environ Contam Toxicol ; 105(3): 372-380, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32705320

RESUMO

Quantum dots (QDs), such as cadmium selenide (CdSe) and lead selenide (PbSe) exhibit excellent optical, magnetic and chemical properties due to their extremely size (ca. 1-10 nm) and are attractive semiconductor nanomaterials for optical studies and energy storage. In this study, aqueous synthesis of CdSe and PbSe QDs in a size range of 2-10 nm was described. Synthesized QDs were characterized using SEM and TEM, DLS, zeta potential, FTIR, EDX and XRD. Highest accumulation (72.5 ± 5.8 mg L-1) of PbSe QDs occurred at 10 ppm suspensions. In general accumulation increased up to 48 h exposure then fluctuate tended to decline. For CdSe QDs, accumulation tended to decrease for 72 h exposure except that for 5 ppm groups. For the elimination period, in general, the elimination levels of PbSe and CdSe QDs from exposed individuals decreased (p < 0.05) even it has some fluctuate.


Assuntos
Artemia/fisiologia , Compostos de Cádmio/toxicidade , Chumbo/toxicidade , Pontos Quânticos/toxicidade , Compostos de Selênio/toxicidade , Animais , Artemia/efeitos dos fármacos , Compostos de Cádmio/química , Compostos de Cádmio/farmacologia , Nanoestruturas , Água/química
3.
Ecotoxicol Environ Saf ; 201: 110813, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32544745

RESUMO

The bioaccumulation potential and toxic effects of engineered nanomaterials (ENMs) to earthworms are poorly understood. Two studies were conducted following OECD TG 222 on Eisenia fetida to assess the effects of CdTe QDs with different coatings and soil ageing respectively. Earthworms were exposed to carboxylate (COOH), ammonium (NH4+), or polyethylene glycol (PEG) coated CdTe QDs, or a micron scale (bulk) CdTe material, at nominal concentrations of 50, 500 and 2000 mg CdTe QD kg-1 dry weight (dw) for 28 days in Lufa 2.2 soil. In the fresh soil study, earthworms accumulated similar amounts of Cd and Te in the CdTe-bulk exposures, while the accumulation of Cd was higher than Te during the exposures to CdTe QDs. However, neither the total Cd, nor Te concentrations in the earthworms, were easily explained by the extractable metal fractions in the soil or particle dissolution. There were no effects on survival, but some retardation of growth was observed at the higher doses. Inhibition of Na+/K+-ATPase activity with disturbances to tissue electrolytes, as well as tissue Cu and Mn were observed, but without depletion of total glutathione in the fresh soil experiment. Additionally, juvenile production was the most sensitive endpoint, with estimated nominal EC50 of values >2000, 108, 65, 96 mg CdTe kg-1 for bulk, PEG-, COOH- and NH4+-coated CdTe QDs, respectively. In the aged soil study, the accumulation of Cd and Te was higher than in the fresh soil study in all CdTe QD exposures. Survival of the adult worms was reduced in the top CdTe-COOH and -NH4+ QD exposures by 55 ±â€¯5 and 60 ±â€¯25%, respectively; and with decreases in growth. The nominal EC50 values for juvenile production in the aged soil were 165, 88, 78 and 63 mg CdTe kg-1 for bulk, PEG-, COOH- and NH4+-coated CdTe QDs, respectively. In conclusion, exposure to nanoscale CdTe QDs, regardless of coating, caused more severe toxic effects that the CdTe bulk material and the toxicity increased after soil ageing. There were some coating-mediated effects, likely due to differences in the metal content and behaviour of the materials.


Assuntos
Compostos de Cádmio/toxicidade , Oligoquetos/efeitos dos fármacos , Pontos Quânticos/toxicidade , Poluentes do Solo/toxicidade , Solo/química , Telúrio/toxicidade , Animais , Bioacumulação , Compostos de Cádmio/química , Compostos de Cádmio/metabolismo , Modelos Teóricos , Oligoquetos/metabolismo , Tamanho da Partícula , Pontos Quânticos/química , Pontos Quânticos/metabolismo , Reprodução/efeitos dos fármacos , Poluentes do Solo/química , Poluentes do Solo/metabolismo , Propriedades de Superfície , Telúrio/química , Telúrio/metabolismo , Fatores de Tempo
4.
Food Chem ; 327: 127075, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32446026

RESUMO

The needing of rapid and sensitive detection method for pesticides is increasing, to facilitate its detection without complicated instruments. Herein, a novel paper-based senor was developed for the visual detection of three carbamate pesticides (metolcarb, carbofuran, and carbaryl) based on CdTe quantum dots (QDs) and nano zinc 5, 10, 15, 20-tetra(4-pyridyl)-21H-23H-porphine (nano ZnTPyP) with a "turn-off-on" mode. This fluorescence sensing model could be applied in the highly selective and sensitive detection of carbamate pesticides both by fluorescence spectrometry or paper-based sensors. Based on the extracted RGB color values of paper, the partial least squares regression (PLSR) was used to accurately quantify the concentrations of carbamate pesticides in different food matrices (apple, cabbage and tea water). This method featured in high speed, low price and high accuracy, and provided a new strategy for the detection of food safety.


Assuntos
Compostos de Cádmio/química , Carbamatos/análise , Análise de Alimentos , Resíduos de Praguicidas/análise , Porfirinas/química , Pontos Quânticos , Telúrio/química , Fluorescência , Alimentos , Limite de Detecção , Nanoestruturas , Espectrometria de Fluorescência
5.
Food Chem ; 328: 127119, 2020 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-32464555

RESUMO

A ratiometric sensor of MOF/ CdTe QDs was constructed by physically mixing CdTe QDs (λem = 605 nm) with MOF (Fe-MIL-88NH2,λem = 425 nm). Under an UV lamp (λex = 365 nm), orange-red CdTe QDs is gradually quenched with increasing levels of Hg2+ or Cu2+, while blue MOF is unchanged, accompanying with a visual change from bright pink to blue fluorescence. Hence, a new method for determining Hg2+ and Cu2+ by MOF/CdTe QDs sensor is established, whose detection limits are 0.22 ng mL-1 for Hg2+ (2.1% RSD) and 0.26 ng mL-1 for Cu2+ (1.1% RSD), respectively. In addition, on-site, rapid and visual determination of Hg2+/Cu2+ in red wine without any pretreatment is realized by using a MOF/CdTe QDs paper-based sensor. For Hg2+ and Cu2+, the semi-quantitative detection ranges of the paper-based sensor are both 10 ~ 5000 ng mL-1, implying that it has great application value in analyzing Hg2+ and Cu2+ in liquid samples.


Assuntos
Compostos de Cádmio/química , Cobre/análise , Mercúrio/análise , Estruturas Metalorgânicas/química , Pontos Quânticos , Telúrio/química , Vinho/análise , Fluorescência , Limite de Detecção , Espectrometria de Fluorescência , Fatores de Tempo
6.
Ecotoxicol Environ Saf ; 196: 110569, 2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-32278141

RESUMO

Cadmium-quantum dots (Cd-QDs) possess unique properties as optoelectronic devices for sensitive detection in food and biomedicine fields. However, the toxic effects of Cd-QDs to single cells is still controversial, due to the release mechanism of QDs to Cd2+in situ and the cytotoxic effects of QDs and Cd2+ respectively are still unclear. In this paper, the release rule of Cd2+ from CdTe QDs within single cells was investigated in situ by using flow cytometry method and the dose-response relationships were explored. Besides, an all-inclusive microscopy system was optimized for live cell imaging to observe the real-time entry process of CdTe QDs into cells. We found that intracellular CdTe QDs and Cd2+ contents were increased based on the dosage and exposing time. A dissociated saturation of Cd2+ from CdTe QDs was exist within cells. CdTe QDs induced more serious cytotoxicity on kidney cells than hepatocytes. The toxicity of oxidative stress, cell apoptosis effects induced by CdTe QDs and Cd2+ are also in consistent with this result. This research develops analytical method to quantify the uptake and release of Cd-QDs to primary cells in situ and can provide technical support in studying the cytotoxicity portion contributed by nanoparticles (NPs) and metal ions.


Assuntos
Compostos de Cádmio/toxicidade , Hepatócitos/efeitos dos fármacos , Rim/efeitos dos fármacos , Pontos Quânticos/toxicidade , Telúrio/toxicidade , Animais , Apoptose/efeitos dos fármacos , Compostos de Cádmio/química , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Rim/citologia , Masculino , Camundongos Endogâmicos C57BL , Estresse Oxidativo/efeitos dos fármacos , Pontos Quânticos/química , Telúrio/química
7.
Chemosphere ; 254: 126868, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32348924

RESUMO

The increasing application of Quantum Dots (QDs) is cause of concern for the potential negative effects for the ecosystem, especially in soils that may act as a sink. In this study, soil leaching experiments were performed in quartz sand packed columns to investigate the behavior of core-shell CdSe/ZnS QDs coated with either small ligands (TGA-QDs) or more complex polymers (POAMA-QDs). Fluorescence emission was compared to mass spectrometric measurements to assess the nanoparticles (NPs) state in both the leachate (transported species) and porous media (deposited amounts). Although both QDs were strongly retained in the column, large differences were observed depending on their capping ligand stability. Specifically, for TGA-QDs elution was negligible and the retained fraction accumulated in the top-columns. Furthermore, 74% of the NPs were degraded and 38% of the Se was found in the leachate in non-NPs state. Conversely, POAMA-QDs were recovered to a larger extent (78.1%), and displayed a higher transport along the soil profile. Further experiments with altered NPs showed that homo-aggregation of the QDs prior injection determined a reduced mobility but no significant changes in their stability. Eventually, ageing of the NPs in the column (15 days) caused the disruption of up to 92% of the original QDs and the immobilization of NPs and metals. These results indicate that QDs will accumulate in top-soils, where transformations phenomena will determine the overall transport, persistency and degradation of these chemicals. Once accumulated, they may act as a source for potentially toxic Cd and Se metal species displaying enhanced mobility.


Assuntos
Pontos Quânticos , Poluentes do Solo/análise , Compostos de Cádmio/química , Ecossistema , Ligantes , Nanopartículas , Compostos de Selênio/química , Solo/química , Sulfetos , Compostos de Zinco
8.
Chemosphere ; 251: 126174, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32151804

RESUMO

In this study, a model crop plant white mustard (Sinapis alba L.) was treated with an aqueous dispersion of silica-coated CdTe quantum dots (CdTe/SiO2 QDs) in a 72-h short-term toxicity test. The toxicity was established via measurements of (i) the root length and (ii) the chlorophyll fluorescence. These results were compared to two other sources of cadmium, free Cd ions (CdCl2) and prime un-shell nanoparticles CdTe QDs. Tested compounds were applied in concentrations representing 20 and 200 µM Cd. The uptake and translocation of Cd were investigated using inductively coupled plasma optical emission spectrometry (ICP-OES) and the spatial Cd distribution was investigated in detail applying laser induced breakdown spectroscopy (LIBS). The LIBS maps with a lateral resolution of 100 µm were constructed for the whole plants, and maps with a lateral resolution of 25 µm (micro-LIBS arrangement) were used to analyse only the most interesting parts of plants with Cd presence (e.g. root tips or a part crossing the root into the above-ground part). Our results show that the bioaccumulation patterns and spatial distribution of Cd in CdTe/SiO2 QDs-treated plants differ from the plants of positive control and CdTe QDs. Fluorescence microscopy photographs revealed that CdTe/SiO2 became adsorbed onto the plant surface in comparison to CdTe QDs. Further, a physico-chemical characterization of QDs before and after the test exposure showed only minor changes in the nanoparticle diameters and no tendencies of QDs for agglomeration or aggregation during the exposure.


Assuntos
Compostos de Cádmio/química , Pontos Quânticos/química , Adsorção , Bioacumulação , Cádmio , Compostos de Cádmio/toxicidade , Microscopia de Fluorescência , Pontos Quânticos/toxicidade , Dióxido de Silício/química , Sinapis/metabolismo , Cloreto de Sódio , Telúrio/química
9.
Food Chem ; 319: 126575, 2020 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-32172051

RESUMO

A core-shell molecular imprinting fluorescence nanosensor was developed for the ratiometric fluorescence and visual detection of folic acid (FA). The nanosensor was prepared by anchoring imprinting shell on the silica nanoparticles, and embedding the CdTe quantum dots in imprinted shell to provide FA-dependent fluorescence signals. Under the optimum conditions, a favorable linearity relationship between the fluorescence intensities ratio (I449/I619) and the FA concentration over 0.23-113 µM was offered with a detection limit (LOD) of 48 nM. The visual detection for FA was realized by evaluating profuse fluorescence color change from red to pink to purple to final blue. The proposed sensor possessed excellent sensing performances of rapid response, high precision, super sensitivity and selective recognition. Furthermore, endogenous FA was detected in real samples ranging from 37.4 to 265.8 µg/100 g; satisfactory spiked recoveries were obtained within 94.8-104.2%, which conformed to the measurement results by HPLC-UV.


Assuntos
Ácido Fólico/análise , Análise de Alimentos/instrumentação , Análise de Alimentos/métodos , Impressão Molecular/métodos , Compostos de Cádmio/química , Cor , Ácido Fólico/química , Limite de Detecção , Nanopartículas/química , Propilaminas/química , Pontos Quânticos/química , Sensibilidade e Especificidade , Silanos/química , Dióxido de Silício/química , Espectrometria de Fluorescência/instrumentação , Espectrometria de Fluorescência/métodos , Telúrio/química
10.
J Vis Exp ; (157)2020 03 06.
Artigo em Inglês | MEDLINE | ID: mdl-32202534

RESUMO

Developments in photovoltaic device architectures are necessary to make solar energy a cost-effective and reliable source of renewable energy amidst growing global energy demands and climate change. Thin film CdTe technology has demonstrated cost-competitiveness and increasing efficiencies due partially to rapid fabrication times, minimal material usage, and introduction of a CdSeTe alloy into a ~3 µm absorber layer. This work presents the close-space sublimation fabrication of thin, 1.5 µm CdSeTe/CdTe bilayer devices using an automated in-line vacuum deposition system. The thin bilayer structure and fabrication technique minimize deposition time, increase device efficiency, and facilitate future thin absorber-based device architecture development. Three fabrication parameters appear to be the most impactful for optimizing thin CdSeTe/CdTe absorber devices: substrate preheat temperature, CdSeTe:CdTe thickness ratio, and CdCl2 passivation. For proper sublimation of the CdSeTe, the substrate temperature prior to deposition must be ~540 °C (higher than that for CdTe) as controlled by dwell time in a preheat source. Variation in the CdSeTe:CdTe thickness ratio reveals a strong dependence of device performance on this ratio. The optimal absorber thicknesses are 0.5 µm CdSeTe/1.0 µm CdTe, and non-optimized thickness ratios reduce efficiency through back-barrier effects. Thin absorbers are sensitive to CdCl2 passivation variation; a much less aggressive CdCl2 treatment (compared to thicker absorbers) regarding both temperature and time yields optimal device performance. With optimized fabrication conditions, CdSeTe/CdTe increases device short-circuit current density and photoluminescence intensity compared to single-absorber CdTe. Additionally, an in-line close-space sublimation vacuum deposition system offers material and time reduction, scalability, and attainability of future ultra-thin absorber architectures.


Assuntos
Compostos de Cádmio/química , Eletricidade , Luminescência , Compostos de Selênio/química , Energia Solar , Sublimação Química , Telúrio/química , Automação , Metais/química , Temperatura , Vácuo , Volatilização
11.
Talanta ; 211: 120711, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32070587

RESUMO

Molecularly imprinted polymer (MIP)-based optosensing materials capable of direct, reliable, and highly selective detection of small organic analytes in complex aqueous samples hold great promise in many bioanalytical applications, but their development remains a challenging task. Addressing this issue, well-defined hydrophilic "turn-on"-type ratiometric fluorescent MIP microspheres are developed via a versatile and modular strategy based on the controlled/"living" radical polymerization method. Its general principle was demonstrated by the synthesis of red CdTe quantum dot (QD)-labeled silica particles with surface-bound atom transfer radical polymerization (ATRP)-initiating groups via the one-pot sol-gel reaction and their successive grafting of a thin fluorescent 2,4-D (an organic herbicide)-MIP layer (labeled with green organic fluorophores bearing both nitrobenzoxadiazole (NBD) and urea interacting groups) and hydrophilic poly(glyceryl monomethacrylate) (PGMMA) brushes via surface-initiated ATRP. The introduction of PGMMA brushes and rationally selected dual fluorescence labeling (i.e., red CdTe QDs being inert to 2,4-D and green NBD showing fluorescence "light-up" upon binding 2,4-D) onto MIP particles afforded them excellent complex aqueous sample-compatibility (due to their largely enhanced hydrophilicity) and analyte binding-induced "turn-on"-type ratiometric fluorescence changes, respectively. Such advanced MIP particles proved to be promising optosensing materials, which had a detection limit of 0.13 µM and showed obvious fluorescent color change upon binding different concentrations of 2,4-D in the undiluted pure milk. Moreover, they were successfully applied for direct and highly selective quantification of 2,4-D in the undiluted pure goat and bovine milks with good recoveries (97.9%-104.5%), even in the presence of several analogues of 2,4-D.


Assuntos
Ácido 2,4-Diclorofenoxiacético/análise , Contaminação de Alimentos/análise , Herbicidas/análise , Leite/química , Animais , Compostos de Cádmio/química , Bovinos , Fluorescência , Cabras , Interações Hidrofóbicas e Hidrofílicas , Metilmetacrilatos/química , Microesferas , Impressão Molecular , Pontos Quânticos/química , Dióxido de Silício/química , Telúrio/química
12.
J Photochem Photobiol B ; 204: 111799, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32018156

RESUMO

CdSe/CdS core shelled quantum dots (QDs) were prepared by colloidal synthesis using a binary ligand system and a non-coordinating, reusable solvent n-octadecane (nOD). Both the synthesis of CdSe and CdSe/CdS core shelled quantum dots were achieved by hot injection technique at much lower temperatures than reported earlier. The use of binary ligand facilitated enough nucleation and growth. Red shift in absorption spectra, an enhanced crystallite and particle size is evidenced by XRD and TEM respectively, confirming the formation of core shell structure of CdSe/CdS. The synthesized core shells exhibited high fluorescence intensity, long term stability and good mono dispersion, making it a potential material for bio-imaging and sensing. Core shell QDs were modified with mercapto propionic acid (MPA) to impart aqueous solubility. Studies on cytotoxicity of shelled QDs reveal good bio compatibility with a very minimum toxicity of IC50 = 20 µg/L. These QDs were used for sensing E. coli. Ordinary glass slide, modified using plasma etching is surface modified through APTES aiding conjugation of antibodies. Anti- E. coli polyclonal antibody on glass matrix (slide) and antibody conjugated QDs were used for detection of E. coli in a typical sandwich model. The excellent optical transparency of glass and high emission of QDs lead to detection of E.coli with a limit of detection of 50 CFU/mL.


Assuntos
Escherichia coli/efeitos dos fármacos , Vidro/química , Pontos Quânticos/química , Animais , Compostos de Cádmio/química , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Camundongos , Microscopia de Fluorescência , Pontos Quânticos/toxicidade , Compostos de Selênio/química , Sulfetos/química , Propriedades de Superfície
13.
Int J Nanomedicine ; 15: 521-536, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32021192

RESUMO

Introduction: The myelodysplastic syndromes (MDS) are a very heterogeneous group of myeloid disorders characterized by peripheral blood cytopenias and increase risk of transformation to acute myeloid leukemia (AML). Daunorubicin (DNR) is an indispensable drug for the treatment of MDS and AML. However, its side effects including cardiac toxicity and bone marrow suppression severely limit clinical application. Many researches reported high expression of CD123 antigen on high-risk MDS cells, so we constructed a novel drug delivery system comprising daunorubicin-loaded CdTe QDs conjugated with anti-CD123 mAbs (DNR-CdTe-CD123) to develop targeted combination chemotherapy for MDS. Methods: CdTe conjugated antiCD123 through amide bond, co-loaded with DNR with electrostatic bonding. Then, we determined characterization and release rate of DNR-CdTe-CD123. The therapeutic effect and side effect of drug delivery system were evaluated through in vitro and in vivo experiments. Results: CdTe showed appropriate diameter and good dispersibility and DNR was loaded into CdTes with high encapsulation efficiency and drug loading. The maximum drug loading and encapsulation efficiency were 42.08 ± 0.64% and 74.52 ± 1.81%, respectively, at DNR concentration of 0.2mg/mL and anti-CD123 mAbs volume of 5ul (100ug/mL). Flow cytometry (FCM) showed that CD123 antigen was highly expressed on MUTZ-1 cells, and its expression rate was 72.89 ± 10.67%. In vitro experiments showed that the inhibition rate and apoptosis rate of MUTZ-1 cells treated with DNR-CdTe-CD123 were higher than those in the other groups (P<0.05). Compared with the other groups, the level of apoptosis-related protein (P53, cleaved caspase-9, Bax and cleaved caspase-3) were upregulated in DNR-CdTe-CD123 group (P<0.05). In vivo experiments, DNR-CdTe-CD123 can effectively inhibit the tumor growth of MDS-bearing nude mice and reduce the side effects of DNR on myocardial cells. Conclusion: The system of DNR-CdTe-CD123 enhances the therapeutic effects and reduce the side effects of DNR, thus providing a novel platform for MDS treatment.


Assuntos
Compostos de Cádmio/química , Daunorrubicina/administração & dosagem , Sistemas de Liberação de Medicamentos/métodos , Síndromes Mielodisplásicas/tratamento farmacológico , Telúrio/química , Animais , Anticorpos Monoclonais/administração & dosagem , Anticorpos Monoclonais/farmacologia , Apoptose/efeitos dos fármacos , Caspase 3/metabolismo , Daunorrubicina/farmacologia , Humanos , Subunidade alfa de Receptor de Interleucina-3/imunologia , Camundongos Endogâmicos BALB C , Camundongos Nus , Síndromes Mielodisplásicas/patologia , Pontos Quânticos/química , Testes de Toxicidade , Ensaios Antitumorais Modelo de Xenoenxerto
14.
Chem Commun (Camb) ; 56(19): 2909-2912, 2020 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-32037421

RESUMO

Herein, a triple-helix molecular switch photoelectrochemical (PEC) biosensor is developed for ultrasensitive and selective detection of microRNA based on position-controllable CdS//CdTe signal enhancement and switching accompanying the signal amplification of a three-dimensional DNA walking machine. The developed PEC biosensor exhibits excellent analytical performance for microRNA-141 detection with a wide linear range from 5 aM to 100 fM, a low detection limit of 1.3 aM and outstanding selectivity.


Assuntos
Técnicas Biossensoriais , Compostos de Cádmio/química , Técnicas Eletroquímicas/instrumentação , MicroRNAs/análise , Processos Fotoquímicos , Sulfetos/química , Telúrio/química , DNA/química , Limite de Detecção
15.
Mater Sci Eng C Mater Biol Appl ; 108: 110372, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31924024

RESUMO

The present study investigates the role of reactive oxygen species (ROS) generated on surface of nanophotocatalyst in wastewater treatment discharged from exponentially growing industries. A facile synthetic route is presented to produce reduced graphene oxide/CdS quantum dot (rGO/CdS QD) heterostructure by monowave-assisted solvothermal method where room temperature ionic liquid 1-ethyl-3-methylimidazolium thiocyanate serves as a "green" precursor. The prepared photocatalyst was tested for: (1) photodegradation performance against various cationic dyes, anionic dyes, and antibiotics as model organic water pollutants; and (2) disinfection performance against gram-positive S. aureus and gram-negative E. coli bacterial strains as pathogenic water pollutants. The negative surface charge of rGO/CdS QD precisely attracted the cationic dye molecules to its surface and degraded the dyes at a higher rate. Moreover, excellent antibacterial activity of rGO/CdS QD were observed against S. aureus and E. coli with a minimum inhibitory concentration of 16 µg ml-1 and 32 µg ml-1, respectively. A plausible mechanism of the photocatalytic activity suggested that ROS with strong oxidizing ability reacts with the organic pollutants to mineralize them into CO2, H2O or some other small molecules, and reacts with pathogens to damage the macromolecules like proteins, lipids, DNA, etc in the bacterial cells. Among all the surface generated ROS, hydroxyl radicals was found to be the main contributor in the photodegradation and disinfection mechanism.


Assuntos
Compostos de Cádmio/química , Desinfecção , Grafite/química , Fotólise , Pontos Quânticos/química , Espécies Reativas de Oxigênio/química , Sulfetos/química , Águas Residuárias/química , Poluentes Químicos da Água/isolamento & purificação , Antibacterianos/farmacologia , Antibacterianos/efeitos da radiação , Corantes/química , Escherichia coli/efeitos dos fármacos , Escherichia coli/ultraestrutura , Fluorescência , Cinética , Testes de Sensibilidade Microbiana , Oxirredução , Pontos Quânticos/ultraestrutura , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/ultraestrutura , Difração de Raios X
16.
Chem Commun (Camb) ; 56(10): 1513-1516, 2020 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-31919482

RESUMO

A potentiometric resolved photoelectrochemical (PEC) system based on CdS nanowires and SnNb2O6 nanosheets was developed. To prove the applicability of this system in PEC multi-biomarker analysis, a label free PEC immunosensor for two cardiac biomarkers, myoglobin and cardiac troponin I, was constructed.


Assuntos
Biomarcadores/análise , Técnicas Eletroquímicas/métodos , Nanoestruturas/química , Nanofios/química , Compostos de Estanho/química , Técnicas Biossensoriais , Compostos de Cádmio/química , Humanos , Mioglobina/análise , Sulfetos/química , Troponina I/análise
17.
J Photochem Photobiol B ; 204: 111783, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31954265

RESUMO

Cadmium sulfide-graphitic carbon nitride nanocomposite was synthesized by pulsed laser ablation in liquid, and it was found from the results of optical and morphological characterizations that the proper anchoring of nanostructured cadmium sulfide on the nano-sheets of graphitic carbon nitride took place, which brought about the positive attributes such as enhanced visible light absorption and reduced photo-generated charge recombination, the key features required for an efficient photo-catalyst by solar light harvesting. The pulsed laser ablation in liquid method adopted for the synthesis of cadmium sulfide-graphitic carbon nitride has the following advantages: the shape and size of the synthesized particles can be controlled by altering the experimental parameters such as laser wavelength, pulse laser duration, the pH of the solution, the surfactants and the temperature of the solution, pulsed laser ablation in liquid method neither requires cumbersome equipment nor does it require intermediate chemicals and catalysts nor does it necessitate the post synthesis purification. The enhancement of photo-catalytic activity of cadmium sulfide-graphitic carbon nitride nanocomposite was tested for the photo-catalytic deactivation of Escherichia coli bacteria in water under visible light radiation. As anticipated, a significant improvement of photo-catalytic deactivation was observed, which is attributed to the enhanced and extended light absorption in the visible spectral region, and the formation of herterojunction between the semiconductors, which is instrumental in inhibiting the undesired recombination of photo-generated charge carriers. Quantitatively, the presence of cadmium sulfide on the graphitic carbon nitride surface contributed to a remarkable 129% increase of photo-catalytic degradation constant compared to pure graphitic carbon nitride, which resulted in the decrease of total depletion time of Escherichia coli from 156 min to 67 min with the cadmium sulfide-graphitic carbon nitride nanocomposite synthesized by pulsed laser ablation in liquid method. Our results on the efficient photo-catalytic deactivation of Escherichia coli under visible light assures that cadmium sulfide-graphitic carbon nitride nanocomposite can very well be used for photo-catalytic water purification by harvesting the abundant solar light.


Assuntos
Compostos de Cádmio/química , Grafite/química , Luz , Nanocompostos/química , Compostos de Nitrogênio/química , Sulfetos/química , Purificação da Água/métodos , Catálise , Escherichia coli/efeitos dos fármacos , Nanocompostos/toxicidade , Estudos Prospectivos
19.
Anal Bioanal Chem ; 412(4): 841-848, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31897553

RESUMO

A sensitive photoelectrochemical (PEC) aptasensor was constructed for prostate-specific antigen (PSA) detection using an enhanced photocurrent response strategy. The p-n heterostructure CdS-Cu2O nanorod arrays were prepared on Ti mesh (CdS-Cu2O NAs/TM) by a simple hydrothermal method and successive ionic-layer adsorption reactions. Compared with the original CdS/TM, the synergistic effect of p-n type CdS-Cu2O NAs/TM and the internal electric field realizes the effective separation of photoinduced electron-hole pairs and improves the PEC performance. In order to construct the aptasensor, an amino-modified aptamer was immobilized on CdS-Cu2O NAs/TM to serve as a recognition unit for PSA. After the introduction of PSA, PSA was specifically captured by the aptamer on the PEC aptasensor, which can be oxidized by photogenerated holes to prevent electron-hole recombination and increase photocurrent. Under optimal conditions, the constructed PEC aptasensor has a linear range of 0.1-100 ng·mL-1 and a detection limit as low as 0.026 ng·mL-1. The results of aptasensor detection of human serum indicate that it has broad application prospects in biosensors and photoelectrochemical analysis.


Assuntos
Aptâmeros de Nucleotídeos/química , Compostos de Cádmio/química , Cobre/química , Nanotubos/química , Antígeno Prostático Específico/sangue , Sulfetos/química , Técnicas Biossensoriais/métodos , Técnicas Eletroquímicas/métodos , Humanos , Limite de Detecção , Nanotubos/ultraestrutura
20.
Anal Bioanal Chem ; 412(6): 1375-1384, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31919610

RESUMO

An enhanced cathodic electrochemiluminescence (ECL) assay for prostate-specific antigen (PSA) is developed based on the in situ activation of a semiconductor nanomaterial. An excellent ECL emitter (CdS/TiO2 nanotubes) was fabricated by the combination of TiO2 nanotubes (NTs) and thioglycolic acid-capped CdS nanocrystals (NCs). After the activation of the hydrogen peroxide-citric acid solution, the ECL signal was enhanced 265 times compared with that of the original TiO2 NT with H2O2 as co-reactant. For the ECL assay, activated CdS/TiO2 NTs were assembled with complementary DNA, PSA aptamer and probe DNA-functionalized SiO2@Pt nanoparticles (NPs) via DNA hybridization to form the detection platform. The SiO2@Pt NPs acted as ECL quencher of CdS/TiO2 NTs. In the presence of PSA, ECL increased after the release of pDNA-SiO2@Pt NPs because of the binding of PSA to the aptamer. An "off-on" ECL phenomenon appeared. The enhanced ECL signals were used for sensitive determination of PSA. The dynamic range was 0.001 to 50 ng mL-1 with a detection limit of 0.4 pg mL-1 (S/N = 3). This new approach conceivably paves the way for fabricating various other enhanced ECL emitter systems, with good application prospects in clinical practice. Graphical abstract The activated CdS/TiO2 nanotubes and SiO2@Pt nanoparticles were synthesized and used to develop an energy-transfer electrochemiluminescence analysis method with high sensitivity and anti-interference performance.


Assuntos
Compostos de Cádmio/química , Nanopartículas/química , Nanotubos/química , Antígeno Prostático Específico/análise , Sulfetos/química , Titânio/química , Humanos , Limite de Detecção , Luminescência , Masculino , Dióxido de Silício/química
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