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ABSTRACT: Fluorescent organic nanoparticles (FONs) as a new class of nanomaterials can provide more advantages than molecule based probes. However, their applications in specific metal ion detection have rarely been exploited. We design and synthesize a branched small-molecule compound with triazole as a core and benzothiadiazole derivative as branches. By a facile reprecipitation method, nanoparticles (NPs) of this compound can be prepared in aqueous solutions, which can show high selectivity and sensitivity to Fe(III) ions based on fluorescence quenching. In addition, the fluorescence intensity of these NPs is resistant to pH changes in solutions. Such characters of this kind of NPs can be utilized in Fe3+ impurity detection in a promising cathode material (LiFePO4) for lithium ion batteries. When exposed to Fe3+, both the triazole and benzothiadiazole groups contribute to the fluorescence quenching of NPs, but the former one plays a more important role in Fe3+ impurity detection. The sensing mechanism has also been investigated which indicates that a Fe-organic complex formation may be responsible for such sensing behavior. Our findings demonstrate that specific metal ion detection can be realized by FONs and have extended the application field of FONs for chemical sensing in aqueous solutions.
ACS Applied Materials & Interfaces 03/2013; · 4.53 Impact Factor
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ABSTRACT: In this paper, a straightforward, economically viable, and green approach for the synthesis of well-stabilized Au/Ag bimetallic nanoparticles is described; this method uses nontoxic and renewable degraded pueraria starch (DPS) as a matrix, and mild reaction conditions. The DPS acted as both a reducing agent and a capping agent for the bimetallic nanoparticles. Au/Ag bimetallic nanoparticles were successfully grown within the DPS matrixes, and the bimetallic structures were characterized using various methods, including high-resolution transmission electron microscopy, energy-dispersive X-ray, and X-ray diffraction. Moreover, it was shown that these DPS-capped Au/Ag bimetallic nanoparticles could function as catalysts for the reduction of 4-nitrophenol in the presence of NaBH4, and were more effective than Au or Ag monometallic nanoparticles.
Langmuir 03/2013; · 4.19 Impact Factor
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ABSTRACT: Oncoprotein platelet derived growth factor-BB (PDGF-BB) is one of the most critical growth factors that regulates tumor growth and division. In this work, a highly sensitive and selective fluorescence resonance energy transfer (FRET) aptasensor for PDGF-BB detection based on the assembly of dye-labeled aptamer and graphene oxide (GO) is developed for the first time. Due to the non-covalent assembly between aptamer and GO, fluorescence quenching of the dye takes place because of FRET. In the presence of PDGF-BB, the binding between aptamer and PDGF-BB will disturb the interaction between aptamer and GO, and release the dye-labeled aptamer from the GO surface, resulting in restoration of the fluorophore fluorescence. Because of the high fluorescence quenching efficiency, unique structure, and electronic properties of GO, the GO aptasensor exhibits extraordinarily high sensitivity. We also demonstrate that two highly related molecular variants of PDGF (AA, AB) can be distinguished from PDGF-BB, which indicates the aptasensor has excellent selectivity. Such an aptasensor opens a rapid, selective and sensitive route for the detection of PDGF-BB and provides a promising strategy for other cancer-related proteins detections.
The Analyst 01/2013; · 4.23 Impact Factor
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ABSTRACT: Poly(ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), a widely-used hole selective layer (HSL) material in polymer solar cells (PSCs), suffers from the problem of being detrimental to the long-term device stability of PSCs due to its high acidity and hygroscopic nature. Here, a method is reported for preparing HSLs derived from polyoxomolybdate solutions via combustion processing, leading to formation of molybdenum oxide (MoO3) at low annealing temperatures, ensuring a high charge-transporting performance similar to PEDOT:PSS but overcoming its defect to device stability. The combustion precursor solution using ammonium heptamolybdate ((NH4)6Mo7O24•4H2O) as the metal source, acetylacetone as a 'fuel', and nitric acid as an oxidizer can largely reduce the temperature for transformation of the polyoxomolybdate to -phase MoO3. Furthermore, when a small amount of PEDOT:PSS has been introduced into the combustion precursor solution to improve the film morphology, the derived film can exhibit a flat and continuous surface morphology with co-existence of - and -MoO3 after being annealed at a very low temperature (150 C). PSCs employing this kind of HSL show a power conversion efficiency comparable to the PEDOT:PSS based device but a significantly prolonged long-term stability. The simplicity, rapidness and effectiveness of our method together with the low annealing temperature (150 °C) needed make it promising for the roll-to-roll manufacture of PSCs.
ACS Applied Materials & Interfaces 01/2013; · 4.53 Impact Factor
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ABSTRACT: As the properties of nanomaterials are strongly dependent on their size, shape and nanostructures, probing the relations between macro-properties and nanostructures is challenging for nanoscientists. Herein, we deliberately chose three types of Ni(OH)(2) with hexagonal, truncated trigonal, and trigonal hourglass-like nanostructures, respectively, as the electrode modifier to demonstrate the correlation between the nanostructures and their electrocatalytic performance towards L-histidine. It was found that the hexagonal hourglass-like Ni(OH)(2) sample had the best electrocatalytic activity, which can be understood by a cooperative mechanism: on one hand, the hexagonal sample possesses the largest specific surface area and the tidiest nanostructure, resulting in the most orderly packing on the electrode surface; on the other hand, its internal structure with the most stacking faults would generate a lot of unstable protons, leading to an enhanced electronic conductivity. The findings are important because they provide a clue for materials design and engineering to meet a specific requirement for electrocatalysis of L-histidine, possibly even for other biomolecules. In addition, the hexagonal Ni(OH)(2) -based biosensor shows excellent sensitivity and selectivity in the determination of L-histidine and offers a promising feature for the analytical application in real biological samples.
Chemistry 12/2012; · 5.93 Impact Factor
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ABSTRACT: In the present work, a facile one-pot method is designed to fabricate a core-shell fluorescent nanoparticle (NP) for cellular imaging based on a new cationic conjugated polymer, poly[9,9'-bis(6,6'-(N,N,N-trimethylaminium)fluorene-2,7-ylenevinylene-co-alt-2,5-dicyano-1,4-phenylene] (PFVCN). Gold nanoflowers (AuNFs) are prepared by a seedless method, in which a gelatin layer formed through a sol-gel phase transition is deposited on the surface of each AuNF. The cationic PFVCN self-assembles onto the negative surface of the resultant (AuNF@Gelatin NPs) driven by electrostatic attraction. An obvious enhancement of fluorescence intensity is observed. The AuNF@Gelatin/PFVCN NPs exhibit excellent cytocompatibility, and their cellular imaging ability is demonstrated by coculture with HeLa cells. AuNF@Gelatin/PFVCN hybrid NPs are expected to be a desirable material in the field of cellular imaging and biosensing.
ACS Applied Materials & Interfaces 12/2012; · 4.53 Impact Factor
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ABSTRACT: In this work, we described a signal-on architecture for electrochemical aptasensors that is applicable to a wide range of aptamers. Herein, we use thrombin as the model sensing target. The signal-on aptasensor is composed of multiple ion channels embedded within a polymeric membrane, with the anti-thrombin aptamers chemically modified onto the inner walls of each ion channel working as the sensing element. As the thrombin concentration increased, [Ru(NH3)6]3+ which was electrostatically absorbed onto the negatively charged phosphate backbones of aptamers beforehand, was displaced and pushed into the ion channels from the inner walls, leading to an increase in the current of redox cations at the working electrode surface. Compared with the traditional two-electrode design using a single ion channel sensing system, our ion channel sensing system is applied multiple times within an ordinary three-electrode system, providing such advantages as a high signal-to-noise ratio and suitability for a wide variety of redox species. The results indicate that multiple ion channel sensing provides improvements of orders of magnitude in signal sensitivity. In particular, this signal-on architecture avoids the problems of limited signal gain and "false positives". Moreover, the proposed aptasensor is simple, highly selective, stable and applicable to real samples.
Analytical Chemistry 11/2012; · 5.86 Impact Factor
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ABSTRACT: A new kind of hybrid core-shell nanosphere was fabricated by combining the in situ formation of Au nanoparticles and covalent crosslinking of biocompatible carboxymethyl starch dialdehyde (CMSD) and chitosan (CTS). When the fluorescent dye poly[9,9'-bis(6"-(N,N,N-trimethylammonium)-hexyl)fluorene-2,7-ylenevinylene-co-alt-1,4-phenylene dibromide] (PFV) was assembled on the surface of the hybrid nanospheres through electrostatic attraction, these biocompatible hybrid nanospheres exhibited metal-enhanced fluorescence effects. The fluorescence intensity of (CTS-Au)@CMSD/PFV hybrid nanosphere is 1.43 times that of CTS-CMSD/PFV hybrid nanospheres lacking Au nanoparticle. In addition, the (CTS-Au)@CMSD/PFV hybrid nanospheres exhibit excellent biodegradability upon exposure to enzymatic aqueous solution, and good biocompatibility when co-cultured with HeLa cervical carcinoma cells, these advantages making them attractive for cellular imaging and biological analysis and detection.
ACS Applied Materials & Interfaces 10/2012; · 4.53 Impact Factor
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ABSTRACT: A flexible free-standing graphene/SnO2 nanocomposites paper (GSP) was prepared by coupling a simple filtration method and a thermal reduction together for the first time. Compared with the pure SnO2 nanoparticles, the GSP exhibited a better cycling stability, because the graphene with high mechanical strength and elasticity can work as a buffer to prevent the volume expansion and contraction of SnO2 nanoparticles during Li+ insertion/extraction process. Meanwhile, compared with single graphene paper, the GSP showed a higher capacity because of the hybridizing with higher capacity SnO2 nanoparticles. The excellent electrochemical performance of the GSP as an anode material in Li-ion battery was obtained. The as-prepared GSP shows a great potential for flexible Li-ion batteries.
ACS Applied Materials & Interfaces 10/2012; · 4.53 Impact Factor
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ABSTRACT: A novel water-soluble conjugated polymer poly{(4,4'-azobenzene)-2,7-[9,9-bis(6'-N,N,N,-trimethylammonium)hexyl fluorene]dibromide} (PFAB) has been designed and synthesized via Suzuki cross-coupling the fluorene units and azobenzene units. Through simple photoreduction, the azo group of the nonfluorescent PFAB to hydrazine group using UV light, polyfluorene PFAB-L with turn-on fluorescence in aqueous solution is obtained. The optical measurements illustrate that the generation of the flexible hydrazine group induces face-to-face arrangement of phenyl-fluorene-phenyl moieties. Therefore, the excimer formation of phenyl-fluorene-phenyl moieties was induced in PFAB-L. And the fluorescence of PFAB-L can be controlled through modulating the protonation of the -NH-NH- group in solution with different pH. The pH-responsive property is reversible. Moreover, the Fe(3+) ions can selectively quench the fluorescence of the PFAB-L. This new polymer PFAB-L could be used for selective and sensitive sensing Fe(3+) ions in aqueous solution.
ACS Applied Materials & Interfaces 09/2012; 4(9):4927-33. · 4.53 Impact Factor
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ABSTRACT: In this Article, large and uniform Ag nanoparticle-containing hybrid hydrogels were prepared by in situ reduction of Ag ions in cross-linked tapioca dialdehyde starch (DAS)-chitosan hydrogels. In the hybrid hydrogels, chitosan was chosen as a macromolecular cross-linker because of its abundant source and good biocompatibility. The hybrid hydrogel showed good water-swelling properties, which could be controlled by varying the ratio of chitosan to tapioca DAS in the hydrogel. The reductive aldehyde groups in the cross-linked hydrogels could be used to reduce Ag ions to Ag nanoparticles without any additional chemical reductants. Interestingly, by controlling the reduction conditions such as the tapioca DAS concentration, aqueous AgNO(3) concentration, reaction time, and aqueous ammonium concentration, Ag nanoparticles with different sizes and morphologies were obtained. Because of their biocompatibility, degradable constituents, mild reaction conditions, and controlled preparation of Ag nanoparticles, these tapioca DAS-chitosan/Ag nanoparticle hybrid hydrogels show promise as functional hydrogels.
Langmuir 07/2012; 28(30):11188-94. · 4.19 Impact Factor
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ABSTRACT: In this work, we described signal amplification architecture for electronic aptamer-based sensor (E-AB), which is applicable to a wide range of aptamers. Herein, we only take lysozyme as the representative sensing target. The amplification method was based on the network of thiocyanuric acid (TCA)/gold nanoparticles (AuNPs) modified with ssDNA. The binding event can be detected by a decrease in the integrated charge of the surface-bound [Ru(NH(3))(6)](3+) which electrostatically absorbed onto the negatively charged phosphate backbones of DNA. In the presence of target molecules, a large amount of TCA/AuNP/ssDNA network associated with [Ru(NH(3))(6)](3+) would be removed from the electrode surface, leading to a significant decrease of redox current. Cyclic voltammetry (CV) signals of [Ru(NH(3))(6)](3+) provides quantitative measures of the concentrations of lysozyme, with a linear calibration ranging from 5 pM to 1 nM and a detection limit is 0.1 pM. The detection limit of the proposed sensor is one order of magnitude and three orders of magnitude more sensitive than the detection limits in the absence of TCA (5 pM) and in the absence of TCA/AuNP/ssDNA network (0.5 nM). This amplification method is promising for broad potential application in clinic assay and various protein analysis.
Biosensors & bioelectronics 05/2012; 38(1):37-42. · 5.43 Impact Factor
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04/2012; , ISBN: 978-953-51-0500-8
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ABSTRACT: In this paper, a novel core-shell hybrid nanoparticle with a silver core and cross-linked poly(3-acrylamidephenylboronic acid-co-acrylic acid) shell (Ag@PAPBA-PAA) was reported. The prepared hybrid nanoparticles can exhibit good responsiveness to the glucose concentration and pH of the environment and exhibit a responsive swelling and shrinking behavior. Tuned by the glucose concentration or pH, a swelling of up to 15.0 nm thickness of the hybrid nanoparticle shell can be observed. These unique responsive properties can be employed to tune the metal-enhanced fluorescence (MEF) effects of the incorporated Ag cores. The fluorescence of adsorbed positively charged porphyrin molecules (Por(4+)) shows good sensitivity to the glucose concentration and pH with an enhancement of up to about 1.8-fold. These functional hybrid nanoparticles with tunable MEF effects show a great potential application in the fields of responsive fluorescent sensing and detection.
ACS Applied Materials & Interfaces 02/2012; 4(3):1747-51. · 4.53 Impact Factor
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ABSTRACT: A facile one-step solution-based process to in situ synthesize SnO(2)/graphene (SG) nanocomposites was developed, by using the mixture of dimethyl sulfoxide (DMSO) and H(2)O as both solvent and reactant. The reduction of graphene oxide (GO) and the in situ formation of SnO(2) nanoparticles were realized in one step. The electrochemical experiments showed the composites provided a better Li-storage performance. The method presented in this paper may provide an effective, economic, and green strategy for the preparation of metal-oxide/graphene nanocomposites.
ACS Applied Materials & Interfaces 12/2011; 4(1):454-9. · 4.53 Impact Factor
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ABSTRACT: Angiogenin (Ang), one of the most potent angiogenic factor, is related with the growth and metastasis of numerous tumors. This paper presents a very simple and label-free square-wave voltammetry (SWV) aptasensor to detect angiogenin, in which an anti-angiogenin-aptamer was used as a molecular recognition element, and the couple ferro/ferricyanide as a redox probe. At the bare gold electrode, the redox couple (K(4)[Fe(CN)(6)]/K(3)[Fe(CN)(6)]) can be very easily accessed to the electrode surface to give a very strong SWV signal. At the anti-angiogenin/Au electrode surface, when angiogenin was added to the electrochemical cell, the binding of the analyte results in less availability for a redox reaction, which led to smaller SWV current. To quantify the amount of angiogenin, current suppressions of SWV peak were monitored using the redox couple of an [Fe(CN)(6)](4-/3-) probe. The plot of signal suppression against the logarithm of angiogenin concentration is linear with over the range from 0.01 nM to 30 nM with a detection limit of 1 pM. The aptasensor also showed very good selectivity for angiogenin without being affected by the presence of other proteins in serum. It is the first time to use a very simple method to detect the cancer marker. Such an aptasensor opens a rapid, selective and sensitive route for angiogenin detection and provides a promising strategy for other protein detections.
Biosensors & bioelectronics 12/2011; 30(1):261-6. · 5.43 Impact Factor
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ABSTRACT: In this paper, we report on the Ag nanoparticle-containing hybrid poly(N-isopropylacrylamide-co-acrylic acid) (PNIPAM-co-PAA) microgels with pH- and thermoresponsive metal-enhanced fluorescence (MEF). The hybrid microgels were prepared by in situ reducing Ag salts to Ag nanoparticles in the PNIPAM-co-PAA microgels. According to the interaction distance-dependent nature of MEF effects, we can realize a controllable MEF effect by adjusting the average interaction distance between fluorophores and Ag nanoparticles due to the good stimuli-responsive swelling-shrinking behavior of the hybrid microgels. The results show that MEF effect can be well tuned in the pH region 2-12 as well as the temperature region of 20-50 °C. By this method, an enhanced fluorescence detection can possibly be manipulated by adjusting external stimuli such as pH and temperature.
Langmuir 11/2011; 28(1):883-8. · 4.19 Impact Factor
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ABSTRACT: Chemically modified graphene has been studied in many applications due to its excellent electrical, mechanical, and thermal properties. Among the chemically modified graphenes, reduced graphene oxide is the most important for its structure and properties, which are similar to pristine graphene. Here, we introduce an environment-friendly approach for preparation of reduced graphene oxide nanosheets through the reduction of graphene oxide that employs L-cysteine as the reductant under mild reaction conditions. The conductivity of the reduced graphene oxide nanosheets produced in this way increases by about 10(6) times in comparison to that of graphene oxide. This is the first report about using amino acids as a reductant for the preparation of reduced graphene oxide nanosheets, and this procedure offers an alternative route to large-scale production of reduced graphene oxide nanosheets for applications that require such material.
Nanotechnology 08/2011; 22(32):325601. · 3.98 Impact Factor
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ABSTRACT: A highly sensitive and specific electrochemical aptasensor for Cu(2+) detection based on gold nanoparticles (AuNPs) is presented. In this work, AuNPs offered a big surface area to immobilize a large number of aptamers and excellent electrochemical signal transduction. Its high sensitivity, low detection limit, and wide detection range are the main advantages over our former copper aptasensor. The peak current increased proportionally to the Cu(2+) concentration over the range from 0.1 nM to 10 μM with a detection limit of 0.1 pM. The presence of other divalent metal ions did not affect the detection of Cu(2+), which indicates a high specificity of Cu(2+) detection could be detected. Rapidity, simplicity, and excellent selectivity make it suitable for practical use in determination of Cu(2+) from lake samples.
Talanta 07/2011; 85(1):730-5. · 3.79 Impact Factor
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ABSTRACT: A sensitive aptasensor for detection of L-histidine based on the switching structure of aptamer and gold nanoparticles-graphene nanosheets (GNPs-GNSs) composite was reported for the first time. The fabricated biosensor shows an expanded linear range, excellent sensitivity and selectivity against other amino acids.
Chemical Communications 05/2011; 47(19):5476-8. · 6.17 Impact Factor
