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ABSTRACT: A facile, economic and green one-step hydrothermal synthesis route using dopamine as source towards photoluminescent carbon nanoparticles (CNPs) is proposed. The as-prepared CNPs have an average size about 3.8 nm. The emission spectra of the CNPs are broad, ranging from approximately 380 (purple) to approximately 525 nm (green), depending on the excitation wavelengths. Due to the favorable optical properties, the CNPs can readily enter into A549 cells and has been used for multicolor biolabeling and bioimaging. Most importantly, the as-prepared CNPs contain distinctive catechol groups on their surfaces. Due to the special response of catechol groups to Fe(3+) ions, we further demonstrate that such wholly new CNPs can serve as a very effective fluorescent sensing platform for label-free sensitive and selective detection of Fe(3+) ions and dopamine with a detection limit as low as 0.32 μM and 68 nM, respectively. The new "mix-and-detect" strategy is simple, green, and exhibits high sensitivity and selectivity. The present method was also applied to the determination of Fe(3+) ions in real water samples and dopamine in human urine and serum samples successfully.
Chemistry 04/2013; · 5.93 Impact Factor
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ABSTRACT: Both human telomeric G-rich and C-rich DNA have been considered as specific drug targets for cancer therapy. However, due to i-motif structure instability and lack of specific binding agents, it remains unclear whether stabilization of telomeric i-motif can inhibit telomerase activity. Single-walled carbon nanotubes (SWNTs) have been reported as the first ligand that can selectively stabilize human telomeric i-motif DNA. Here we report that SWNTs can inhibit telomerase activity through stabilization of i-motif structure. The persistence of i-motif and the concomitant G-quadruplex eventually leads to telomere uncapping and displaces telomere-binding proteins from telomere. The dysfunctional telomere triggers DNA damage response and elicits upregulation of p16 and p21 proteins. This is the first example that SWNTs can inhibit telomerase activity and interfere with the telomere functions in cancer cells. These results provide new insights into understanding the biomedical effects of SWNTs and the biological importance of i-motif DNA.
Nature Communications 09/2012; 3:1074. · 7.40 Impact Factor
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ABSTRACT: Natural DNA has been considered as a building block for developing novel functional materials. It is abundant, renewable, and biodegradable and has a well-defined structure and conformation with many unique features, which are difficult to find in other polymers. Herein, calf thymus DNA modified graphene/Pd nanoparticle (DNA-G-Pd) hybrid materials are constructed for the first time using DNA as a mediator, and the prepared DNA-G-Pd hybrid shows high catalytic activity for fuel cell formic acid electro-oxidation and for organic Suzuki reaction. The main advantages of using DNA are not only because the aromatic nucleobases in DNA can interact through π-π stacking with graphene basal surface but also because they can chelate Pd via dative bonding in such defined sites along the DNA lattice. Our results indicate that isolated, homogeneous, and ultrafine spherical Pd nanoparticles are densely in situ decorated on DNA-modified graphene surfaces with high stability and dispersibility. The prepared DNA-G-Pd hybrid has much greater activity and durability for formic acid electro-oxidation than the commercial Pd/C catalyst and polyvinylpyrrolidone-mediated graphene/Pd nanoparticle (PVP-G-Pd) hybrid used for direct formic acid fuel cells (DFAFCs). Besides, the DNA-G-Pd hybrid can also be an efficient and recyclable catalyst for the organic Suzuki reaction in aqueous solution under aerobic conditions without any preactivation. Since DNA can chelate various transition metal cations, this proof-of-concept protocol provides the possibility for the tailored design of other novel catalytic materials based on graphene with full exploitation of their properties.
ACS Applied Materials & Interfaces 09/2012; 4(9):5001-9. · 4.53 Impact Factor
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ABSTRACT: We report a smart therapeutic nanoplatform based on Fe(3)O(4)@CaP capped gold nanocages, which integrates magnetic targeting, photothermal therapy and chemotherapy for killing cancer cells. Combining photothermal- and chemo-therapy results in a synergistic effect in cancer treatment.
Chemical Communications 06/2012; 48(61):7640-2. · 6.17 Impact Factor
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ABSTRACT: Luminescent carbon nanoparticles (CNPs) are newcomers to the world of nanomaterials and have shown great impact in health
and environmental applications as well as being promising building blocks for future nanodevices because of their fascinating
photoluminescence and potential to serve as nontoxic replacements for traditional heavy-metals-based quantum dots. Herein,
fluorescent CNPs have been prepared from candle soot by refluxing with HNO3 and subsequently separated by a single centrifugation. The CNPs can be represented by the empirical formula C1H0.677O0.586N0.015Na0.069, and have a size of 20–100 nm, height of 3.0 nm, lifetime of 7.31 ns ± 0.06 ns and quantum yield of ∼1.7%. Further studies
demonstrate that: (1) the as-prepared CNPs exhibit excellent stability in biological media and their luminescence intensity
does not change with ionic strength or pH in the physiological and pathological range of pH 4.5–8.8; (2) CNPs can act as electron
donors and transporters and porphyrin can assemble onto CNPs through electrostatic and π-stacking interactions to form porphyrin-CNPs
supramolecular composites; (3) CNPs have strong intrinsic peroxidase-like activity. Based on this intrinsic peroxidase activity,
a simple, cheap, and highly selective and sensitive colorimetric and quantitative assay has been developed for the detection
of glucose levels. This assay has been used to analyze real samples, such as diluted blood and fruit juice.
KeywordsCarbon nanoparticles–luminescence–supramolecular assembly–peroxidase–biosensing
Nano Research 04/2012; 4(9):908-920. · 6.97 Impact Factor
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ABSTRACT: A novel strategy to dissociate amyloid aggregation is presented, using localised heat generation from a clinically used amyloid staining dye, thioflavin-S (ThS)-modified graphene oxide (GO) under NIR laser irradiation. Compared to traditional chemotherapies, photothermal therapy shows reduced side effects and improved selectivity and safety.
Advanced Materials 03/2012; 24(13):1722-8. · 13.88 Impact Factor
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ABSTRACT: Strontium ions play important roles in biological systems. The inhalation of strontium can cause severe respiratory difficulties, anaphylactic reaction and extreme tachycardia. Strontium can replace calcium in organisms, inhibit normal calcium absorption and induce strontium "rickets" in childhood. Thus, the development of sensitive and selective methods for the determination of trace amounts of Sr(2+) in aqueous media is of considerable importance for environmental and human health protection. A number of methodologies, such as X-ray energy dispersive spectrometry, inductively coupled argon plasma atomic emission spectroscopy (ICP-AES), atomic absorption spectrometry (AAS) and instrumental thermal neutron activation analysis, have been reported. However, these methods are somewhat complex, costly, time consuming and, especially, need special instruments. Thus, the design of convenient and inexpensive approaches for the sensitive and selective detection of Sr(2+) with rapid, easy manipulation is in ever-increasing demand. To the best of our knowledge, using DNA conformational change to detect Sr(2+) has not yet been reported. Herein we utilized thiazole orange (TO) as a signal reporter to devise a simple Sr(2+) detection assay based on Sr(2+) induced human telomeric DNA conformational change in the presence of SWNTs. The limit of detection is 10 nM Sr(2+) (0.87 μg L(-1)), far below 4 mg L(-1), the U.S. Federal threshold in drinking water defined by the U.S. EPA.
Molecular BioSystems 12/2011; 8(3):779-82. · 3.53 Impact Factor
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ABSTRACT: Both graphene oxide (GO) and DNA can be used as building blocks for nano/micro devices or hybrid structures. Reversible assembly of these nanomaterials is highly desirable because of their promising applications in chemical sensors, energy storage, catalysis, and optoelectronic applications. However, reversible assembly of GO-DNA hybrid materials has not been achieved based on specific DNA hybridization and conformational transition. Here we report a general pH-responsive, DNA-directed assay for the design of a reversible assembly of GO-GO and GO-AuNPs hybrid using human telomeric G-quadruplex and i-motif DNA.
Molecular BioSystems 09/2011; 7(9):2681-7. · 3.53 Impact Factor
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ABSTRACT: Single-walled carbon nanotubes (SWNTs) have received much attention in nanotechnology because of their potential applications in molecular electronics, field-emission devices, biomedical engineering, and biosensors. Carbon nanotubes as gene and drug delivery vectors or as "building blocks" in nano-/microelectronic devices has been successfully explored. However, since SWNTs lack chemical recognition, SWNT-based electronic devices and sensors are strictly related to the development of a bottom-up self-assembly technique. Here we present an example of using DNA duplex-based protons (H(+)) as a fuel to control reversible assembly of SWNTs without generation of waste duplex products that poison DNA-based systems.
Chemistry 06/2011; 17(25):7013-9. · 5.93 Impact Factor
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ABSTRACT: As a promising strategy for artificially control of gene expression, reversible assembly of nanomaterials and DNA nanomachine, DNA triplex formation has received much attention. Carbon nanotubes as gene and drug delivery vector or as 'building blocks' in nano/microelectronic devices have been successfully explored. Therefore, studies on triplex DNA-based carbon nanotube hybrid materials are important for development of smart nanomaterials and for gene therapy. In this report, a small molecule directed single-walled carbon nanotubes (SWNTs) self-assembly assay has been developed by disproportionation of SWNTs-dT(22)·dA(22) duplex into triplex dT(22)·dA(22)·dT(22) and dA(22) by a triplex formation inducer, coralyne. This has been studied by circular dichroism, light scattering (LS) spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), electrophoretic mobility shift assay and supported by using DNA random sequence. In contrast, SWNTs do not aggregate under the same experimental conditions when the small molecules used can not induce dT(22)·dA(22)·dT(22) triplex formation. Therefore, this novel small molecule-directed SWNTs self-assembly assay has also been used for screening of triplex inducers in our studies.
Nucleic Acids Research 02/2011; 39(9):3939-48. · 8.03 Impact Factor
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Journal of Materials Chemistry 01/2011; 21:2445-2450. · 5.97 Impact Factor
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Advanced Functional Materials 12/2010; 21(3):583 - 590. · 10.18 Impact Factor
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ABSTRACT: Herein we report that a visual, label-free gold nanoparticle-based assay for rapid and efficient screening of Alzheimer's disease β-amyloid inhibitors.
Molecular BioSystems 10/2010; 6(12):2389-91. · 3.53 Impact Factor
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ABSTRACT: A novel luminescent Eu3+-complex functionalized single-walled carbon nanotube (SWNT) was constructed by covalent linkage through a diaminotriethylene glycol linker. TGA, FT-IR, and SEM demonstrated successful attachment of the Eu3+-complex onto the SWNT surface. Spectroscopic methods showed that the SWNT-Eu3+ complex is highly luminescent and DNA can further enhance the red luminescence, and the enhancement depends on DNA sequence and form. The order of the enhancement follows: AT alternative dsDNA > nonalternative AT dsDNA > GC dsDNA > ssDNA dA > ssDNA dT > ssDNA (GT)20.
09/2010;
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ABSTRACT: Here we combine click chemistry and carbon nanotube peroxidase-like catalytic colour reaction together to develop a turn-on, highly sensitive and selective copper sensor.
Chemical Communications 09/2010; 46(35):6572-4. · 6.17 Impact Factor
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Advanced Functional Materials 08/2010; 20(22):3967 - 3971. · 10.18 Impact Factor
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ABSTRACT: Here we report a reusable DNA single-walled carbon nanotube (SWNT)-based fluorescent sensor for highly sensitive and selective detection of Ag(+) and cysteine (Cys) in aqueous solution. SWNTs can effectively quench the fluorescence of dye-labeled single-stranded DNA due to their strong pi-pi stacking interactions. However, upon incubation with Ag(+), Ag(+) can induce stable duplex formation mediated by C-Ag(+)-C (C=cytosine) coordination chemistry, which has been further confirmed by DNA melting studies. This weakens the interactions between DNA and SWNTs, and thus activates the sensor fluorescence. On the other hand, because Cys is a strong Ag(+) binder, it can remove Ag(+) from C-Ag(+)-C base pairs and deactivates the sensor fluorescence by rewrapping the dye-labeled oligonucleotides around the SWNT. In this way, the fluorescence signal-on and signal-off of a DNA/SWNT sensor can be used to detect aqueous Ag(+) and Cys, respectively. This sensing platform exhibits high sensitivity and selectivity toward Ag(+) and Cys versus other metal ions and the other 19 natural amino acids, with a limit of detection of 1 nM for Ag(+) and 9.5 nM for Cys. Based on these results, we have constructed a reusable fluorescent sensor by using the covalent-linked SWNT-DNA conjugates according to the same sensing mechanism. There is no report on the use of SWNT-DNA assays for the detection of Ag(+) and Cys. This assay is simple, effective, and reusable, and can in principle be used to detect other metal ions by substituting C-C base pairs with other native or artificial bases that selectively bind to other metal ions.
Chemistry 07/2010; 16(27):8147-54. · 5.93 Impact Factor
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Advanced Materials 05/2010; 22(19):2206-10. · 13.88 Impact Factor
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Chemistry 02/2010; 16(12):3617-21. · 5.93 Impact Factor
