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1.
Small ; : e1903398, 2019 Oct 03.
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.

2.
Anal Chem ; 91(19): 12453-12460, 2019 Oct 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.

3.
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
4.
Mikrochim Acta ; 186(8): 567, 2019 Jul 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.

5.
Mikrochim Acta ; 186(8): 490, 2019 Jul 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.

6.
Nanotechnology ; 30(47): 475503, 2019 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-31349242

RESUMO

Electrochemical methods have been deemed effective strategies for the detection of dye additive sunset yellow (SY) owing to their low cost, good stability, and high sensitivity. However, the application of the existing sensors with single electrical signal response is limited by their inadequate sensitivity and large background interference. Herein, a ratiometric electrochemical strategy with a dual signal was developed to detect SY. The strategy had an intrinsic built-in correction to the effects from the system, and thus reduced the influence of environmental change. 3D polyethyleneimine functionalized reduced graphene oxide aerogels@Au nanoparticles/SH-ß-cyclodextrin (PEI-rGAs@AuNPs/SH-ß-CD) was used as the sensing material due to its 3D macroporous microstructure with high specific surface area and excellent electronic conductivity. Guest molecule methylene blue (MB) was chosen as a probe molecule, which formed an inclusion host-guest complex with a SH-ß-CD host in advance. The target molecule SY displaced MB from the CD cavities, resulting in the decrease of MB current and the increase of SY current. With the logarithmic value of ISY/IMB as the readout signal, the detection limit of the developed ratiometric electrochemical sensor reached as low as 0.3 nM, confirming the excellent sensitivity. Furthermore, this strategy exhibited good selectivity and repeatability, and could be used for the detection of SY in a real sample.

7.
Chem Commun (Camb) ; 55(51): 7335-7338, 2019 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-31169289

RESUMO

It is highly important to develop cost-efficient electrocatalysts for the oxygen evolution reaction (OER). In this communication, we report a novel FeS-NiS hybrid nanosheet array on Ti mesh as a highly efficient non-noble-metal electrocatalyst for OER. This catalyst requires an overpotential of 260 mV to afford a current density of 10 mA cm-2 in 1.0 M KOH, 100 and 110 mV less than those required for FeS and NiS, respectively. In addition, this catalyst shows good durability, with maintenance of its catalytic activity for at least 25 h.

8.
Biosens Bioelectron ; 139: 111312, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-31136922

RESUMO

Photoelectrochemical (PEC) biosensor for highly sensitive detection of breast cancer biomarker human epidermal growth factor receptor-2 (HER2) is reported utilizing a dual signal amplification strategy. The biosensor was prepared based on tungsten sulfide nanowire array on Ti mesh (WS2 NW/TM). Such WS2 NW/TM electrode can generate photoelectric signal under visible light excitation. The HER2 aptamer was wrapped onto the nanowire array surface for specific binding with HER2 molecules, and gold nanoparticles (Au NPs) that modified with glucose oxidase (GOx) and HER2 binding peptide was utilized for signal amplification. The H2O2 that generated by GOx catalyzed glucose reaction and localized surface plasmon resonance of Au NPs can both enhance the PEC current intensity of the biosensor, leading to dual signal amplification. The PEC current intensity is enhanced linearly with HER2 concentration in the 0.5-10 ng/mL range with limit of detection of 0.36 ng/mL. Such biosensor was applied for the detection of HER2 in breast cancer serum samples with detection results in good agreement with commercial ELISA results.

9.
Mikrochim Acta ; 186(5): 291, 2019 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-31016395

RESUMO

Nanosheets of tungsten disulfide (WS2) were used to improve the physicochemical properties of reduced graphene oxide aerogel (rGA). The nanosheets were directly integrated into 3D hybrid architecture of rGA by a solvothermal mixing method by which the WS2 sheets were assembled onto the conductive graphene network. WS2 with highly exfoliated and defect-rich structure made the WS2/rGA composite possess plentiful active sites, and this enhanced the electrocatalytic capability of the composite. The introduction of poorly conductive WS2 into 3D rGA system decreases the background current of rGA when used as electrode material. This is advantageous in terms of signal to-noise ratio and analytical performance in general. The WS2/rGA electrode, best operated at a potential of 0.68 V (vs. SCE) has a linear response in the 0.01 to 130 µM nitrite concentration range with a low detection limit of 3 nM (at S/N = 3). It is selective, reproducible, stable and is successfully applied to the determination of nitrite in spiked bacon samples. Graphical Abstract Schematic presentation of an electrochemically modified electrode for the detection of nitrite based on 3D tungsten disulfide/reduced graphene oxide aerogel (WS2/rGA).

10.
Mikrochim Acta ; 186(5): 282, 2019 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-30989411

RESUMO

A fluorometric turn-on assay is described for ascorbic acid (AA). It is based on the controlled release of polyallylamine-stabilized gold nanoclusters (polyallylamine-AuNCs) from MnO2 nanosheets. In an aqueous solution of near-neutral pH value, the positively charged capped AuNCs are adsorbed on the surface of the negatively charged MnO2 nanosheets. The adsorption leads to the quenching of the fluorescence of the AuNCs. However, in the presence of AA, MnO2 is reduced to Mn2+. This causes the destruction of the MnO2 nanosheets. As a result, the fluorescence of the polyallylamine-AuNCs at 615 nm is recovered. This method for determination of AA is inexpensive, sensitive, and selective. It works in the 0.01 to 200 µM concentration range and has a 3.2 nM detection limit (for S/N = 3). Graphical abstract Gold nanoclusters (AuNCs) and polyallylamine can form polyallylamine-AuNCs to enhance the orange fluorescence of AuNCs. MnO2 nanosheets can absorb polyallylamine-AuNCs, and this results in fluorescence quenching of polyallylamine-AuNCs. Ascorbic acid (AA) can reduce MnO2 nanosheets, in this results in the fluorescence recovery of polyallylamine-AuNCs.

11.
Chem Commun (Camb) ; 55(17): 2469-2472, 2019 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-30734789

RESUMO

The development of new electrocatalysts is critical for efficient water electrolysis to produce hydrogen. In this communication, we report a novel electrocatalyst for the oxygen evolution reaction (OER) which is realized via Fe doping in CoS2 nanosheets (Fe-CoS2). This catalyst shows an overpotential of 302 mV for a current density of 10 mA cm-2, 85 mV less than that for CoS2. In addition, Fe-CoS2 also exhibits high catalytic stability.

13.
Mikrochim Acta ; 186(2): 73, 2019 01 09.
Artigo em Inglês | MEDLINE | ID: mdl-30627836

RESUMO

A method is described for photoelectrochemical determination of the activity of alkaline phosphatase (ALP). It employs an indium tin oxide (ITO) electrode modified a CdS quantum dots@graphene (CdS@GR) composite and hexagonal cobalt oxyhydroxide (CoOOH) nanosheets. The CdS@GR nanocomposite was synthesized by assembling the CdS quantum dots onto a GO film to receive a basic photocurrent response of the ITO. This is further improved by covering it with CoOOH nanosheets. Secondly, 2-phospho-L-ascorbic acid (AAP) is added as a substrate for ALP. Its hydrolysis yields ascorbic acid which reduces CoOOH to form cobalt(II) ion. As a result, the CoOOH nanosheets decompose. This is accompanied by a reduction of the photocurrent. The effect was used to design a selective and sensitive assay of determination of the activity of ALP. Under the optimized experimental conditions, response is linear in the 10 to 300 U·L-1ALP activity range. The detection limit is 1.5 U·L-1 at a signal-to-noise ratio of 3. Graphical abstract Indium tin oxide (ITO) was coted with CdS@graphene and CoOOH to obtain a material with superior photoelectrochemical properties. The detection of alkaline phosphatase (ALP) was accomplished by using 2-phospho-L-ascorbic acid (AAP) which is hydrolyzed by ALP to release ascorbic acid (AA) which reduces CoOOH to Co2+.

14.
Talanta ; 194: 55-62, 2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30609572

RESUMO

We present a fluorescence turn-on and colorimetric dual-readout sensing system for the sensitive detection of alkaline phosphatase (ALP) activity via self-assembled gold nanoclusters (AuNCs) based on fluorescence resonance energy transfer (FRET). The positively charged polyallylamine hydrochloride (PAH)-crosslinked AuNCs (PAH-AuNCs) with aggregation-induced enhancement (AIE) characteristics can electrostatically adsorb the negatively charged 2, 6-dichlorophenolindophenol (DCIP). Thus, the fluorescence of PAH-AuNCs can be significantly quenched by the occurrence of FRET from PAH-AuNCs to DCIP. However, the reduction reaction of DCIP from blue to colourless by L-ascorbic acid (AA) which is generated by the ALP catalyse hydrolysis of 2-Phospho-L-ascorbic acid (AAP) disturbs the FRET between PAH-AuNCs to DCIP. The quenched PAH-AuNCs fluorescence can be recovered efficiently. The strategy of first creating AIE-enhanced PAH-AuNCs, followed by the effective FRET manipulation, is an important contribution to the sensitive detection of ALP. More importantly, the distinct colorimetric signal change can be used to visually distinguish the presence of ALP. More importantly, the distinct colorimetric signal change can be used to visually distinguish the presence of ALP. Good linear relationships of fluorescence and colorimetric sensing towards ALP were obtained in the range from 0.5 to 100 U/L, and the detection limits were 0.2 U/L and 0.5 U/L, respectively. In addition, the proposed FRET sensing system was applied to the detection of ALP in human serum samples with satisfactory results. The simple and efficient sensing approach proposed here has the potential to promote the development of chemo/biodetection methods using fluorescence and colorimetric dual-readout.

15.
Nanoscale ; 10(46): 21617-21624, 2018 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-30457152

RESUMO

Increasing demand for hydrogen energy has boosted the exploration of inexpensive and effective catalysts. Transition metal phosphides (TMPs) have been proven as excellent catalysts for the hydrogen evolution reaction (HER). Very recently, the search for TMP-based catalysts has being mainly directed at enhanced electrocatalytic performance. Hence, a concluded guideline for enhancing HER activity is highly desired. In this mini review, we briefly summarize the most recent and instructive developments in the design of TMP-based catalysts with enhanced electrocatalysis for hydrogen evolution from composition and structure engineering strategies. These strategies and perspectives are also meaningful for designing other inexpensive and high-performance catalysts.

16.
Chem Commun (Camb) ; 54(91): 12848-12851, 2018 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-30374491

RESUMO

NH3 synthesis heavily depends on the energy-intensive Haber-Bosch process, which produces serious carbon emission. Electrocatalytic N2 reduction emerges as an environmentally benign process for sustainable artificial N2 fixation but requires efficient, stable and selective catalysts for the N2 reduction reaction (NRR). Here, we report that Cr2O3 nanofiber behaves as a superb non-noble-metal NRR electrocatalyst for artificial N2 fixation to NH3, with excellent selectivity under ambient conditions. In 0.1 M HCl, this catalyst achieves a high Faradaic efficiency of 8.56% and a high NH3 formation rate of 28.13 µg h-1 mgcat.-1, placing it amongst the most active aqueous-based NRR electrocatalysts. Moreover, this catalyst also shows strong electrochemical durability during electrolysis and the recycling test. It opens a new avenue to explore the rational design of Cr-based nanostructures as advanced catalysts for N2 fixation and other applications.

17.
Analyst ; 143(22): 5388-5394, 2018 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-30295305

RESUMO

Heparin (Hep) is widely used as a major anticoagulant in surgery. Simple and sensitive methods capable of quantitative detection of Hep are desired for better regulating its clinical use. Herein, a novel nanoassembly of amino-functionalized mesoporous silica nanoparticle-gold nanoclusters (MSN-AuNCs) with remarkable emission enhancement characteristics for sensitive fluorescence detection of Hep is developed. The electrostatic interaction between the positively charged amino-functionalized MSNs and the AuNC-stabilizing surface ligands triggers the self-assembly of MSN-AuNC nanocomposites which exhibit more than 5-fold fluorescence emission enhancement. However, the presence of negatively charged Hep inhibits the emission enhancement phenomenon due to the effective wrapping of Hep on the surface of MSNs, which blocks the interaction between AuNCs and MSNs. Benefitting from the remarkable emission enhancement and the competing binding of Hep, facile and ultrasensitive detection of Hep can be realized with a detection limit as low as 2 nM. Moreover, the successful application of the proposed method for detection of Hep in human serum samples shows promise for clinical applications.

18.
Analyst ; 143(22): 5474-5480, 2018 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-30288517

RESUMO

Since bleomycins (BLMs) play a prominent role in the clinical treatment of various cancers, the development of convenient and sensitive detection assays for BLM is of great significance in cancer therapy and related biological mechanism research. Here, taking advantage of the easily controllable and excitation of the G-triplex DNA structure, we reported a facile, label-free G-triplex based functional molecular beacon (G3MB) sensing system for fluorescence "turn-on" detection of BLM based on BLM-Fe(ii) mediated DNA strand scission. In the presence of BLM, the stable hairpin structure of G3MB undergoes an irreversible cleavage in the loop region that contains a 5'-GT-3' recognition site for BLM. The released G-tract DNA fragment self-assembles into a G-triplex-ThT complex showing a strong fluorescence. Owing to the effective locking of G-tracts in the stem of the G3MB and the specific DNA strand scission by BLM which is like a key for the release of G-tracts, the assay shows high sensitivity and selectivity with a detection limit of 0.2 nM. In addition, satisfactory results were obtained for the detection of BLM in human serum samples. Critically, the convenient "mix-and-detect" protocol, fast response and no need for modifying DNA offered a potential application of the proposed strategy for BLM assay in biomedical and clinical studies.

19.
Chem Commun (Camb) ; 54(72): 10100-10103, 2018 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-30124709

RESUMO

Developing earth-abundant and efficient catalysts for the hydrogen evolution reaction (HER) is highly desirable. In this communication, we report the development of a Mn-doped Ni3S2 nanosheet array on Ni foam (Mn-Ni3S2/NF) as a superior and durable catalyst for alkaline hydrogen evolution. Such Mn-Ni3S2/NF demands an overpotential of 152 mV to afford 10 mA cm-2 in 1.0 M KOH, 46 mV less than that for Ni3S2/NF. Furthermore, this catalyst also shows high long-term electrochemical durability. This work provides important guidance for exploring optimal HER catalysts.

20.
Chem Commun (Camb) ; 54(42): 5323-5325, 2018 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-29736524

RESUMO

The development of a sustainable route to ammonia production is one of the most attractive targets in chemistry. The primary method of ammonia production, Haber-Bosch process, can bring about excessive consumption of fossil fuels and large CO2 emission. In this communication, we develop a VN nanowire array on carbon cloth (VN/CC) as a high-performance catalyst for the nitrogen reduction reaction (NRR) under ambient conditions. Such an electrocatalyst achieves high ammonia yield (2.48 × 10-10 mol-1 s-1 cm-2) and faradaic efficiency (3.58%) at -0.3 V versus RHE in 0.1 M HCl, outperforming most reported results for N2 fixation under ambient conditions, and even comparing favorably with those obtained under high temperatures and/or pressures. This work not only provides us an attractive catalyst material for the NRR in acidic media, but would also open up an exciting new avenue to the rational design and fabrication of transition metal nitrides for the NRR.

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