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1.
Analyst ; 145(19): 6254-6261, 2020 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-32985630

RESUMO

Determination of glutathione (GSH) is closely related to the clinical diagnosis of many diseases. Thus, a fluorescent and colorimetric dual-readout strategy for the sensitive determination of glutathione was proposed. The mesoporous silica nanoparticle-gold nanocluster (MSN-AuNC) nanocomposites with significantly enhanced emission and effectively improved photostability characteristics were used as fluorescent probes. Based on the inner filter effect (IFE), the fluorescence of MSN-AuNCs at 570 nm can be effectively quenched by oxidized 3,3',5,5'-tetramethylbenzidine (oxTMB) with absorption in the wavelength ranges of 330-470 nm and 500-750 nm. However, the addition of GSH could cause the reduction of blue oxTMB to colorless TMB, resulting in the inhibition of IFE and the recovery of the fluorescence of MSN-AuNCs. Therefore, using oxTMB as both quencher and color indicator, a dual-readout oxTMB/MSN-AuNC sensing system for the sensitive determination of GSH was constructed. As signal amplification is caused by the fluorescence enhancement of MSN-AuNCs, the detection limits as low as 0.12 µM and 0.34 µM can be obtained for fluorescent and colorimetric assay, respectively. This method may not only offer a new idea for the sensitive and effective determination of GSH, but also broaden the applications of AuNCs in fluorescent and colorimetric dual-readout bioanalysis.

2.
Biosens Bioelectron ; 167: 112481, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32798806

RESUMO

Construction of novel photoelectrochemical (PEC) materials with unique structures can effectively improve the photoelectric conversion efficiency. Here, a self-supported Cu2O@Cu-MOF/copper mesh (CM) nanobelt arrays with high specific surface area, high orientation, and high photoelectric conversion performance is obtained by in-situ grown strategy. Such PEC aptasensor is constructed based on the Cu2O@Cu-MOF/CM combined with rolling circle amplification and enzymatic biocatalytic precipitation for vascular endothelial growth factor 165 analysis. This strategy achieves excellent cooperative signal amplification, which greatly improves the detection sensitivity. The PEC aptasensor exhibited a wide calibration ranged from 10 to 1 × 108 fM with a detection limit down to 2.3 fM (S/N = 3). The construction of semiconductor@MOFs has developed the potential application of MOFs in photoelectrochemical and found a reliable path for ultrasensitive detection of biomarkers.

3.
Mikrochim Acta ; 187(6): 325, 2020 05 12.
Artigo em Inglês | MEDLINE | ID: mdl-32399626

RESUMO

A facile and sensitive self-powered cathodic photoelectrochemical (PEC) aptasensor is reported for the detection of prostate-specific antigen (PSA) based on CuO-Cu2O nanowire array grown on Cu mesh (CuO-Cu2O NWA/CM) as electrode. The mixed narrow band gaps of the CuO-Cu2O heterostructure ensured its wide absorption band, effective electron/hole separation, and high photocatalytic activity in the visible region. In addition, nanowires directly grown on the substrate provided high specific surface area and exposed abundant active sites, thus guaranteeing its high photocatalytic efficiency. Therefore, the self-powered sensor exhibited favorable analytical performance with fast response, wide linear ranges of 0.01 to 5 ng/mL and 5 to 100 ng/mL, an acceptable detection limit of 3 pg/mL, and reasonable selectivity and stability. The proposed CuO-Cu2O NWA/CM can be considered a promising visible light-responsive photoactive material for fabrication of PEC aptasensor with high performance. Graphical abstract a Schematic illustration of construction process of PEC sensing platform based on the CuO-Cu2O composite for PSA detection. b Schematic mechanism of the operating PEC system.

4.
Talanta ; 215: 120891, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32312436

RESUMO

A novel electrochemical sensor was constructed based on three-dimensional NiO@Ni-MOF nanoarrays modified Ti mesh (NiO@Ni-MOF/TM). NiO nanoarrays were firstly produced on conductive TM using hydrothermal and carbonization method, and then Ni-MOFs were directly grown on the surface of NiO nanoarrays through self-template strategy. The morphology and structure of the prepared materials were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The as-prepared NiO@Ni-MOF/TM was used as electrochemical sensor for investigating electrochemical behaviors of luteolin flavonoid. The composite electrode combined the excellent enrichment ability of Ni-MOF, high catalysis of NiO nanoarrays with the superior electronic conductivity of TM substrate, enabling ultra-sensitive detection towards luteolin with a low limit of detection (LOD) of 3 pM (S/N = 3). Besides, with favorable stability and selectivity, the fabricated sensor was applied in the determination of luteolin in actual samples with satisfactory results.

5.
Mikrochim Acta ; 187(5): 258, 2020 04 04.
Artigo em Inglês | MEDLINE | ID: mdl-32248309

RESUMO

Flower-like graphene/CuO@Cu-BTC (GR/CuO@Cu-BTC) composite was employed as electrode material for the voltammetric determination of caffeic acid (CA) in the wine. The composite material was prepared via the self-template method. In this synthetic process, budlike CuO not only acts as the template, but also provides Cu2+ ions for in situ growth of the Cu-BTC shell. The utilization of GR as petal greatly boosts the stability and electronic conductivity of CuO@Cu-BTC. The GR/CuO@Cu-BTC composite possesses unique structural features with high specific surface area and good conductivity, exhibiting excellent electrocatalytic activity towards the oxidation of CA. Under optimized conditions, the sensor shows a good linear response to CA concentration over the range 0.020-10.0 µM, together with a low limit of detection (LOD) of 7.0 nM. Selectivity, reproducibility, and stability were investigated, and the method has been applied for the determination of CA in wine samples. Graphical abstract Schematic representation of electrochemical sensor for the detection of caffeic acid was designed based on flower-like graphene/copper oxide@copper(II) metal-organic framework (GR/CuO@Cu-BTC) composite electrode material.

6.
J Hazard Mater ; 396: 122776, 2020 09 05.
Artigo em Inglês | MEDLINE | ID: mdl-32334288

RESUMO

Pesticides play an important role in agricultural fields, but the pesticide residues pose strong hazardous to human health, thus designing sensitive and fast method for pesticides monitor is highly urgent. Herein, nanoarchitecture of Mxene/carbon nanohorns/ß-cyclodextrin-Metal-organic frameworks (MXene/CNHs/ß-CD-MOFs) was exploited as electrochemical sensing platform for carbendazim (CBZ) pesticide determination. ß-CD-MOFs combined the properties of host-guest recognition of ß-CD and porous structure, high porosity and pore volume of MOFs, enabling high adsorption capacity for CBZ. MXene/CNHs possessed large specific surface area, plenty of available active sites, high conductivity, which afforded more mass transport channels and enhances the mass transfer capacity and catalysis for CBZ. With the synergistic effect of MXene/CNHs and ß-CD-MOFs, the MXene/CNHs/ß-CD-MOFs electrode extended a wide linear range from 3.0 nM to 10.0 µM and a low limit of detection (LOD) of 1.0 nM (S/N = 3). Additionally, the prepared sensor also demonstrated high selectivity, reproducibility and long-term stability, and satisfactory applicability in tomato samples.

7.
Talanta ; 212: 120768, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-32113538

RESUMO

This study demonstrates a novel and convenient ratiometric fluorescent method for the detection of alkaline phosphatase (ALP) activity. Amino-functionalized mesoporous silica nanoparticle-gold nanoclusters (MSN-AuNCs) nanocomposites were integrated with o-phenylenediamine (OPD) to form a ratiometric fluorescence nanoplatform. The presence of ALP induced the generation of quinoxaline (QX) derivative which called 3-(dihydroxyethyl)furo[3,4-b]quinoxaline-1-one (DFQ) with strong fluorescence emission at 450 nm, while the orange-red fluorescence of MSN-AuNCs at 580 nm was slightly quenched. Meanwhile, an obvious fluorescence color change from orange-red to purple and finally to blue can be observed by naked eyes with the increasing of ALP concentration. Therefore, employing the fluorescence emission of DFQ at 450 nm as the reporter signal and the fluorescence emission of MSN-AuNCs at 580 nm as a reference signal, a sensitive ratiometric detection method for ALP was developed. Quantitative detection of ALP activity in the linear range from 0.2 to 80 U/L with a detection limit of 0.1 U/L can be realized in this way, which endows the assay with high sensitivity enough for practical detection of ALP in human serum samples.

8.
Analyst ; 145(4): 1362-1367, 2020 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-32040108

RESUMO

Although the potential of gold amalgam as a nanoenzyme has been demonstrated, its practical utility has been limited by its low catalytic activity caused by the aggregation of Au nanoparticles (Au NPs). Thus, there is a need to further engineer Au NPs to prevent aggregation and then to achieve higher enzyme activities for the detection of Hg2+ ions. Metal organic frameworks (MOFs), as one kind of promising material, have attracted particular attention due to their unique characteristics of uniform cavities and very high porosity. Herein, a hybrid material of Au nanoparticles and a MOF (AuNP@MOF), constructed by immobilization of Au NPs uniformly on the cavity surface of an iron-5,10,15,20-tetrakis (4-carboxyl)-21H,23H-porphyrin-based MOF (Fe-TCPP-MOF), has been successfully synthesized. Based on Hg2+ ion triggered Au catalysis of methylene blue (MB) reduction, a colorimetric method for highly sensitive and selective detection of Hg2+ ions has been established. The Hg2+ ions were first bound to the Au NP surface to form gold amalgam, and then the catalytic activity of Au NPs was initiated. This detection method showed the advantages of a fast response time, and high sensitivity and selectivity. The response time and the limit of detection were as low as 2 s and 103 pM, respectively, benefiting from the uniform cavities and the large specific surface area of Fe-TCPP-MOF, which ensure: (1) uniform dispersion of the Au NPs on the surface of the cavity; and (2) a higher chance of interaction of mercury and MB owing to the gathering effect of Fe-TCPP-MOF.

9.
Anal Chem ; 92(4): 3366-3372, 2020 02 18.
Artigo em Inglês | MEDLINE | ID: mdl-31995981

RESUMO

Mercury detection remains an important task because of its high toxicity. Herein a new dual-signal probe based on a boric acid (BA)-functionalized lanthanide metal-organic framework (BA-Eu-MOF) was developed for the detection of Hg2+ and CH3Hg+ ions for the first time. The BA-Eu-MOF was synthesized by coordination of Eu3+ with 5-boronobezene-1, 3-dicarboxylic acid (5-bop) through a one-pot method. The 5-bop ligand not only acted as the "antenna" to sensitize the luminescence of Eu3+ but also provided reaction sites for Hg2+ and CH3Hg+. Owing to the electron-withdrawing effect of the BA group, the "antenna" effect of the ligand was passivating and the BA-Eu-MOF showed weak red emission in water. Upon addition of Hg2+ or CH3Hg+ into the system, a transmetalation reaction took place, i.e., BA groups were replaced by Hg2+ or CH3Hg+; therefore, the "antenna" effect of the ligand was triggered, leading to the enhancement of red emission. As Hg2+ or CH3Hg+ concentration increased, the red emission was gradually enhanced, and the color change was also observed with the naked eye under 365 nm ultraviolet light. Owing to the porous characteristics and the surface effect of the MOF, as well as the unique transmetalation reaction between the BA group and Hg2+ or CH3Hg+, the developed nanoprobe showed excellent characteristics for simultaneous detection of Hg2+ and CH3Hg+, such as simple preparation, convenient operation, "turn-on" signal output, high sensitivity, and selectivity. The unique features of the BA-Eu-MOF make it an attractive probe for monitoring Hg2+ and CH3Hg+.

10.
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
11.
Anal Bioanal Chem ; 412(6): 1317-1324, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31927600

RESUMO

Herein, a dual-emission metal-organic framework based ratiometric fluorescence nanoprobe was reported for detecting copper(II) ions. In particular, carbon dots (CDs) and gold nanoclusters (AuNCs) were embedded into ZIF-8 (one of the classical metal-organic frameworks) to form CDs/AuNCs@ZIF-8 nanocomposites, which exhibited dual-emission peaks at UV excitation. In the presence of Cu2+, the fluorescence attributed to AuNCs can be rapidly quenched, while the fluorescence of CDs serves as reference with undetectable changes. Therefore, the CDs/AuNCs@ZIF-8 nanocomposites were utilized as a ratiometric fluorescence nanoprobe for sensitive and selective detection of Cu2+. A good linear relationship between the ratiometric fluorescence signal of CDs/AuNCs@ZIF-8 and Cu2+ concentration was obtained in the range of 10-3-103 µM, and the detection limit was as low as 0.3324 nM. The current ratiometric fluorescence nanoprobe showed promising prospects in cost-effective and rapid determination of Cu2+ ions with good sensitivity and selectivity. Furthermore, this nanoprobe has been successfully applied for the quantitative detection of Cu2+ in serum samples, indicating its value of practical application. Graphical abstract Carbon dots (CDs) and gold nanoclusters (AuNCs) were embedded into metal-organic frameworks (ZIF-8) to form CDs/AuNCs@ZIF-8 nanocomposites, which exhibited dual-emission peaks at 365 nm excitation. In the presence of Cu2+, the fluorescence emission peak at 574 nm can rapidly respond by quenching, while the fluorescence at 462 nm serves as reference with undetectable changes.


Assuntos
Carbono/química , Cobre/análise , Ouro/química , Nanopartículas Metálicas/química , Estruturas Metalorgânicas/química , Pontos Quânticos/química , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Cobre/sangue , Humanos , Limite de Detecção
12.
Biosens Bioelectron ; 150: 111875, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31757562

RESUMO

An ultrasensitive photoelectrochemical (PEC) biosensor was constructed based on gold nanoparticles (Au NPs)/tungsten sulfide nanorod array (WS2 NA) photoelectrode as the PEC matrix and silver nanoparticles/flake-like zinc metal-organic framework (Ag/ZnMOF) nanozyme with the peroxidase mimetic enzyme property for sensitive detection of bleomycin (BLM). In particular, Au/WS2 and Ag/ZnMOF were linked by thiolate DNA1 and DNA2 strand, respectively, and the Au/WS2-Ag/ZnMOF probe was prepared via hybridization reaction between the two DNAs. The introduction of Ag/ZnMOF in the probe offers two functions: i) the steric hindrance effect can effectively impede electron transport and reduce the photocurrent; ii) Ag/ZnMOF nanozyme can also be used as mimic peroxidase to effectively catalyze 3,3-diaminobenzidine (DAB) to produce the relevant precipitation, which will further reduce photocurrent and eliminate false positive signals. When BLM exists, BLM with Fe2+ as irreversible cofactor can specifically recognize and cleave of the 5'-GC-3' active site of DNA2, resulting in reduced precipitation deposited on the electrode and recovery of PEC signal. The highly sensitive PEC biosensor exhibits a the linear strategy from 0.5 nM to 500 nM with a detection limit down to 0.18 nM. Further, the unique strategy was conducted in biological samples for BLM detection with satisfactory consequence, offering available and efficient pathway for disease diagnosis.

13.
Spectrochim Acta A Mol Biomol Spectrosc ; 228: 117855, 2020 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-31784222

RESUMO

G-triplexes have been reported recently with the similar function to G-quadruplex that can combine with thioflavin T (ThT) and emit strong fluorescence but easier to be controlled and excited. In this work, we report an Hg2+-mediated stabilization of G-triplex based functional molecular beacon (G3TMB) sensing system for the label-free detection of Hg2+, reduced glutathione (GSH), and glutathione reductase (GR) activity. In the presence of Hg2+, the extended G-triplex sequence containing the "T" bases can form a stable hairpin structure due to the strong interactions of "T-Hg2+-T", resulting in the locking of G-tracts in the stem of the G3TMB effectively. However, the hairpin structure of the G3TMB can be opened by the introduction of GSH through the stronger "GSH-Hg2+" interaction. Therefore, by employing the fact that GR can catalyze the reduction of oxidized glutathione (GSSG) into GSH, this concept can be applied to fluorescence "off-on" detection of GR activity, with a linear range of 0.02-30 mU/mL and detection limit of 0.01 mU/mL. This work may expand a new perspective of G-triplex based functional molecular beacon as the label-free fluorescent probes in the detection of small biomolecule and enzyme activity.

14.
Spectrochim Acta A Mol Biomol Spectrosc ; 227: 117607, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31654846

RESUMO

The level of alkaline phosphate (ALP) is a significant biomarker index in organism. In this work, a label-free and sensitive G-quadruplex fluorescence assay for monitoring ALP activity has been developed with the assistance of Cu2+ based on the competitive binding effect between pyrophosphate (PPi) and G-quadruplex-N-methylmesoporphyrin (G4/NMM) complex to Cu2+. In the sensing assay, the G4/NMM complex is employed as a signal indicator, while the Cu2+ as a quencher and the PPi as recovery agent as well as the hydrolytic substance for ALP. In details, the fluorescence of the G4/NMM complex was efficiently quenched by introducing Cu2+ due to the proximal carboxylate groups of NMM coordinating with the Cu2+ as well as the unfolding of G-quadruplex by Cu2+, while the higher affinity between PPi and Cu2+ could lead to the fluorescence recovery. However, in the presence of ALP, the PPi was hydrolyzed to phosphate ions (Pi) which cannot integrate with Cu2+, resulting in the fluorescence quenching once again. Thus, a simple and facile way to inspect ALP has been exploited. The proposed assay shows a good linear relationship in the range from 0.5 to 100 U/L with the detection limit of 0.3 U/L. Moreover, the fabricated method is succeeded in detecting ALP in human serum samples, indicating the potential as a profitable candidate in biological and biomedical application.

15.
Small ; 16(15): e1903398, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31583803

RESUMO

Inorganic halide perovskite quantum dots (IHPQDs) have recently emerged as a new class of optoelectronic nanomaterials that can outperform the existing hybrid organometallic halide perovskite (OHP), II-VI and III-V groups semiconductor nanocrystals, mainly due to their relatively high stability, excellent photophysical properties, and promising applications in wide-ranging and diverse fields. In particular, IHPQDs have attracted much recent attention in the field of photoelectrochemistry, with the potential to harness their superb optical and charge transport properties as well as spectacular characteristics of quantum confinement effect for opening up new opportunities in next-generation photoelectrochemical (PEC) systems. Over the past few years, numerous efforts have been made to design and prepare IHPQD-based materials for a wide range of applications in photoelectrochemistry, ranging from photocatalytic degradation, photocatalytic CO2 reduction and PEC sensing, to photovoltaic devices. In this review, the recent advances in the development of IHPQD-based materials are summarized from the standpoint of photoelectrochemistry. The prospects and further developments of IHPQDs in this exciting field are also discussed.

16.
Mikrochim Acta ; 186(11): 740, 2019 11 04.
Artigo em Inglês | MEDLINE | ID: mdl-31686245

RESUMO

A luminescent metal organic framework (LMOF) of type UiO-66-NH2 was chosen for specific and sensitive detection of trace levels of hypochlorite. Hypochlorite causes the quenching of the blue fluorescence of nano-UiO-66-NH2 (with excitation/emission maxima at 325/430 nm), and this finding forms the basis for a fluorometric assay for hypochlorite. The method overcomes disadvantages of conventional redox-probes which are interfered by oxidants with oxidation capability stronger than that of hypochlorite. Compared with other fluorescent probes for sensing hypochlorite, UiO-66-NH2 has a comparable detection limit of 0.3 µmol L-1 and a broad linearity relationship in the range of 1-8 µmol L-1. The probe was successfully applied to the detection of hypochlorite in complex water samples and living Hela cells. Graphical abstract Schematic representation of hypochlorite induced quenching of the blue fluorescence of nano-UiO-66-NH2 (with excitation/emission maxima at 325/430 nm) through energy transfer. It overcomes disadvantages of conventional redox-probes which are interfered by oxidants with oxidation capability stronger than that of hypochlorite.


Assuntos
Corantes Fluorescentes/química , Ácido Hipocloroso/análise , Estruturas Metalorgânicas/química , Microscopia Confocal/métodos , Microscopia de Fluorescência/métodos , Espectrometria de Fluorescência/métodos , Água Potável/análise , Transferência de Energia , Fluorescência , Células HeLa , Humanos , Limite de Detecção , Nanopartículas/química , Piscinas , Poluentes Químicos da Água/análise
17.
Anal Chem ; 91(19): 12453-12460, 2019 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-31466442

RESUMO

Ferric ion (Fe3+) plays a vital role in cellular homeostasis. However, the detection of Fe3+ with rhodamine B (RhB) has potential problems, such as poor selectivity and low photostability. To address these problems, we rationally designed an RhB@MOF nanocomposite-based "on-off-on" fluorescent switching nanoprobe for highly sensitive and selective detection of Fe3+ and ascorbic acid. This RhB@MOF nanoprobe was prepared through a facile one-pot synthesis. Here MOF served as a selectivity regulator for the detection of Fe3+. By embedding RhB into the porous crystalline MOF, enhanced photostability and fluorescence lifetime of RhB to Fe3+ were achieved. The as-prepared RhB@MOF was demonstrated to be an ultrasensitive and selective nanoprobe for the detection of Fe3+ in human serum and ascorbic acid in rat brain microdialysate. Furthermore, inner filter effect (IFE) and photoinduced electron transfer (PET) were proposed and discussed to explain the selectivity and sensitivity of RhB to Fe3+ against other interfering substances. Our novel "on-off-on" nanoprobe provides insight into the rational design of MOF-based biosensors for selective and sensitive detection of analytes.

18.
Mikrochim Acta ; 186(8): 567, 2019 07 24.
Artigo em Inglês | MEDLINE | ID: mdl-31338696

RESUMO

An enzyme-free electrochemical method is described for the determination of trace levels of malathion. It is based on a nanostructured copper-cerium oxide (CuO-CeO2) composite prepared by calcination of a Cu(II)/Ce(III) metal-organic framework. The morphology, crystal structure and elemental composition of composite was studied by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The principle for malathion determination is based on the fact that the redox signal of CuO (best measured at around -0.1 V vs. SCE) (at 100 mV/s) is inhibited by malathion due to affinity between CuO and the sulfur groups of malathion. The introduction of CeO2 into the composite system further improves the analytical performance. This is attributed to the unique microstructure and the synergistic effect between CuO and CeO2. Experimental parameters like solution pH value, Cu/Ce molar ratio, accumulation potential, accumulation time, and CuO-CeO2 volume on the electrode were optimized. The assay has a linear range of 10 fM to 100 nM and a 3.3 fM detection limit (at S/N = 3). The electrode is selectively inhibited by malathion even in the presence of potentially interfering substances. Graphical abstract A sensitive and effective enzyme-free electrochemical sensor has been developed for the detection of malathion based on CuO-CeO2 composite derived from bimetallic metal-organic frameworks.


Assuntos
Cério/química , Cobre/química , Técnicas Eletroquímicas/métodos , Malation/análise , Estruturas Metalorgânicas/química , Nanocompostos/química , Eletrodos , Inseticidas/análise , Limite de Detecção , Oxirredução
19.
Chem Commun (Camb) ; 55(65): 9653-9656, 2019 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-31342021

RESUMO

The fast and accurate real-time monitoring of hydrogen peroxide (H2O2) secreted from living cells plays a critical role in clinical diagnosis and management. Herein, we report low-cost and self-supported MoS2 nanosheet arrays for non-enzymatic eletrochemical H2O2 detection. Under the optimal test conditions, such MoS2 electrodes exhibit extremely promising electrocatalytic performance with a low detection limit of 1.0 µM (S/N = 3) and an excellent sensitivity of 5.3 mA mM-1 cm-2. Furthermore, the detection of the trace amount of H2O2 secreted from live A549 cancer cells was successfully performed with this biosensor.


Assuntos
Dissulfetos/química , Peróxido de Hidrogênio/análise , Molibdênio/química , Nanoestruturas/química , Células A549 , Técnicas Biossensoriais/métodos , Carbono/química , Dissulfetos/síntese química , Técnicas Eletroquímicas/métodos , Humanos , Limite de Detecção
20.
Mikrochim Acta ; 186(8): 490, 2019 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-31267219

RESUMO

A photoelectrochemical (PEC) method has been developed for sensitive detection of trypsin. It is based on the use of a composite consisting of MoS2 nanosheets and TiO2 nanorods (MoS2-TiO2). The material has a high specific surface area, superior electrical conductivity, excellent biocompatibility and good band gap matching. The composite was synthesized by a one-pot method using TiO2 as a template. This results in a uniform distribution of the MoS2 nanosheets (<5 layers) in the composite. If the composite, placed on an indium tin oxide (ITO) electrode, is coupled to apoferritin, the photocurrent response decreases due to the insulating effect of the protein. Trypsin, in acting as an alkaline protease, decomposes the apoferritin. This results in the recovery of the PEC signal. Attractive features of this PEC method include (a) a superior PEC signal, (b) sensor stability, (c) simple operation, and (d) the lack of any additional modifications of the biosensor. This warrants high sensitivity, reproducibility, repeatability and practicality. The ITO sensor has a linear response in the 1 to 1000 ng·mL-1 trypsin concentration range and a 0.82 ng·mL-1 detection limit. The assay was applied to the determination of trypsin in spiked serum samples and gave satisfactory results. Graphical abstract Schematic presentation of an indium tin oxide (ITO)/MoS2-TiO2 sensor for detecting trypsin. The PEC signal was decreased after immobilization of apoferritin (APO) on the modified ITO. Trypsin catalytically hydrolyzes APO specifically and induces the PEC signal to recover.


Assuntos
Técnicas Biossensoriais , Tripsina/análise , Catálise , Dissulfetos/química , Dissulfetos/efeitos da radiação , Técnicas Eletroquímicas , Eletrodos , Humanos , Luz , Molibdênio/química , Molibdênio/efeitos da radiação , Nanoestruturas/química , Nanoestruturas/efeitos da radiação , Processos Fotoquímicos , Compostos de Estanho/química , Titânio/química , Titânio/efeitos da radiação , Tripsina/sangue , Tripsina/química
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