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ABSTRACT: A highly efficient upconversion-C60 nanoplatform was demonstrated for NIR imaging-guided photodynamic therapy of cancer.
Chemical Communications 03/2013; · 6.17 Impact Factor
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ABSTRACT: Although high quality aqueous CdTe and CdTeS alloyed quantum dots (QDs) have been synthesized in recent years, the relationship between the fluorescent properties and the growth kinetics has not been well documented yet. In this paper, 3-mercaptopropionic acid stabilized aqueous CdTe nanocrystals (NCs) are generally prepared with an improvement of the "traditional" synthetic approach, where the preparation of the red emission NCs is usually time-consuming due to the slow growth rate. The investigation on the kinetic and thermodynamic growth process shows that the growth can be effectively accelerated by decreasing the ligand concentration from 0.06 to 0.01 mol/L or elevating the growth temperature from 120 to 240 degrees C. In contrast to previous results, the quantum yield (QY) of the CdTe NCs is heightened to 45% only by increasing properly the growth rate. Our experiments depict that high growth rate favours high concentration of free monomers and thus decreases the number of the surface Te atoms of the NCs, leading to the enhancement of the photoluminescence (PL) QY.
Journal of Nanoscience and Nanotechnology 02/2013; 13(2):858-63. · 1.56 Impact Factor
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ABSTRACT: In this study, deep blue, pure electroluminescence (EL) at 441.5 nm from a ZnSe/ZnS quantum dot light-emitting device (QD-LED) is obtained by using poly (4-butylphenyl-diphenyl-amine) (poly-TPD) as the hole-transport layer (HTL) to open up the channel for energy transfer from poly-TPD to QDs. The emission originating from HTL is observed in the QD-LED with N,N<sup>'</sup>-bis (tolyl)-N,N<sup>'</sup>-diphenyl-1,1<sup>'</sup>-biphenyl-4,4<sup>'</sup>-diamine functionalized with two styryl groups (2-TPD) as the HTL due to inefficient energy-transfer from 2-TPD to QDs. The poly-TPD based device exhibits color-saturated blue emission with a narrow spectral bandwidth of full width at half maximum (∼17.2 nm). These results explore the operating mechanism of the QD EL and signify a remarkable progress in deep blue QD-LEDs based on environmental-friendly QD materials.
Optics Letters 01/2013; 38(1):7-9. · 3.40 Impact Factor
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Kai Liu,
Xiaomin Liu,
Qinghui Zeng,
Youlin Zhang,
Langping Tu,
Tao Liu, Xianggui Kong,
Yinghui Wang,
Feng Cao,
Saskia A G Lambrechts,
Maurice C G Aalders,
Hong Zhang
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ABSTRACT: A highly efficient multifunctional nanoplatform for simultaneous upconversion luminescence (UCL) imaging and photodynamic therapy has been developed on the basis of selective energy transfer from multicolor luminescent NaYF(4):Yb(3+),Er(3+) upconversion nanoparticles (UCNPs) to photosensitizers (PS). Different from popular approaches based on electrostatic or hydrophobic interactions, over 100 photosensitizing molecules were covalently bonded to every 20 nm UCNP, which significantly strengthened the UCNP-PS linkage and reduced the probability of leakage/desorption of the PS. Over 80% UCL was transferred to PS, and the singlet oxygen production was readily detected by its feature emission at 1270 nm. Tests performed on JAR choriocarcinoma and NIH 3T3 fibroblast cells verified the efficient endocytosis and photodynamic effect of the nanoplatform with 980 nm irradiation specific to JAR cancer cells. Our work highlights the promise of using UCNPs for potential image-guided cancer photodynamic therapy.
ACS Nano 04/2012; 6(5):4054-62. · 10.77 Impact Factor
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ABSTRACT: To be able to label a gene and monitor its migration are key important approaches for the clinical application of cancer suicide gene therapy. Photonic nanomaterials are introduced in this work. One of the most promised suicide genes - herpes simplex virus thymidine kinase (HSV-TK) gene - is successfully linked with CdTe/CdS core/shell quantum dots (QDs) via EDC/NHS coupling method. From confocal microscopy it was demonstrated that plasmid TK intracellular trafficking can be effectively and distinctly traced via monitoring the luminescence of the QDs up to 96 h after transfection of QDs-TK conjugates into Hela cells. MTT results show that the QDs-TK conjugates have a high efficient cytotoxicity after adding GCV into Hela cells, whereas the QDs exert no detectable deleterious effects on the cellular processes. The apoptosis induced by QDs-TK conjugates with GCV is distinctly traced partly due to the strong luminescence of the QDs. Our results indicate that photonic nanomaterials, e.g. QDs, provide a tool for monitoring TK gene delivery and anti-cancer activity.
Biomaterials 03/2012; 33(17):4336-44. · 7.40 Impact Factor
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ABSTRACT: Multi-sized quantum dots (QDs) donors and tailor-made gold nanorods (GNRs) are employed to form a FRET nanoplatform for homogeneous immunoassays developed for analysis of multiple virus antigens. The single GNRs/multiple QDs nanocomposite based nanosensor offers a simple and sensitive approach for multiple analytes detection in a homogeneous format.
Chemical Communications 01/2012; 48(12):1781-3. · 6.17 Impact Factor
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ABSTRACT: LRET-based optical biosensor of an aptamer-upconversion conjugate was constructed. It is demonstrated that photosensitized breakage and damage of aptamers are eliminated by employing UCNPs as donors, and the as-designed biosensor is specific and sensitive in the detection of ATP.
Chemical Communications 12/2011; 48(8):1156-8. · 6.17 Impact Factor
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ABSTRACT: The concentration quenching threshold of upconversion luminescence was broken through for the first time via a designed strategy: spatial separation of the emitter doping area.
Chemical Communications 11/2011; 47(43):11957-9. · 6.17 Impact Factor
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ABSTRACT: Almost all the luminescence upconversion nanoparticles used for Förster resonant energy transfer (FRET) applications are bare cores based on the consideration that the energy transfer efficiency is optimized because the distance between energy donors and acceptors is minimized. On the other hand, it is well proved that core/shell structure is efficient in minimizing the nonradiative loss of excitation energy of the luminescence donors. In this work we use core/shell upconversion NaYF4:Yb3+,Er3+@NaYF4 nanoparticles and rose bengal photosensitizer to construct a FRET conjugate. From the photophysics and singlet oxygen generation we have determined that the core/shell structured nanoparticles are better than bare cores for FRET applications. More importantly, we have found that there exists a critical shell thickness for the best FRET performance. In the model we have established, the critical shell thickness is a trade-off between the opposing optimal conditions for upconversion and FRET efficiency. This work shall lead to more efficient FRET-based applications of nanomaterials.Keywords: core/shell; upconversion; nanoparticle; photosensitizer; FRET; critical shell thickness
08/2011;
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ABSTRACT: A novel inorganic-organic composite ultrathin film was fabricated by layer-by-layer assembly of naphthol green B (NGB) and layered double hydroxides (LDHs) nanoplatelets, which shows remarkable electrocatalytic behavior for oxidation of ascorbic acid. LDHs nanoplatelets were prepared using a method involving separate nucleation and aging steps (particle size: 25±5 nm; aspect ratio: 2-4) and used as building blocks for alternate deposition with NGB on indium tin oxide (ITO) substrates. UV-vis absorption spectroscopy and XRD display regular and uniform growth of the NGB/LDHs ultrathin film with extremely c-orientation of LDHs nanoplatelets (ab plane of microcrystals parallel to substrates). A continuous and uniform surface morphology was observed by SEM and AFM image. The film modified electrode displays a couple of well-defined reversible redox peaks attributed to Fe(2+)/Fe(3+) in NGB (ΔE(p)=68 mV and I(a)/I(c)=1.1). Moreover, the modified electrode shows a high electrocatalytic activity towards ascorbic acid in the range 1.2-55.2 μM with a detection limit of 0.51 μM (S/N=3). The Michaelis-Menten constant was calculated to be K(M)(app)=67.5 μM.
Talanta 07/2011; 85(1):493-8. · 3.79 Impact Factor
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ABSTRACT: The ordered ultrathin films (UTFs) based on CoFe-LDH (layered double hydroxide) nanoplatelets and manganese porphyrin (Mn-TPPS) have been fabricated on ITO substrates via a magnetic-field-assisted (MFA) layer-by-layer (LBL) method and were demonstrated as an electrochemical sensor for glucose. The XRD pattern for the film indicates a long-range stacking order in the normal direction of the substrate. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) images of the MFA LDH/Mn-TPPS UTFs reveal a continuous and uniform surface morphology. Cyclic voltammetry, impedance spectroscopy, and chronoamperometry were used to evaluate the electrochemical performance of the film, and the results show that the MFA-0.5 (0.5 T magnetic field) CoFe-LDH/Mn-TPPS-modified electrode displays the strongest redox current peaks and fastest electron transfer process compared with those of MFA-0 (without magnetic-field) and MFA-0.15 (0.15 T magnetic field). Furthermore, the MFA-0.5 CoFe-LDH/Mn-TPPS exhibits remarkable electrocatalytic activity toward the oxidation of glucose with a linear response range (0.1-15 mM; R(2) = 0.999), low detection limit (0.79 μM) and high sensitivity (66.3 μA mM(-1) cm(-2)). In addition, the glucose sensor prepared by the MFA LBL method also shows good selectivity and reproducibility as well as resistance to poisoning in a chloride ion solution. Therefore, the novel strategy in this work creates new opportunities for the fabrication of nonenzyme sensors with prospective applications in practical detection.
Langmuir 06/2011; 27(13):8233-40. · 4.19 Impact Factor
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ABSTRACT: Physical and chemical properties of nanoparticles are known to be subject to the surface factors. For their biological/biomedical applications, typically, surface of the nanoparticles has to be modified which inevitably affects their performance. In this work we have studied the interaction between the surface related organic vibrational modes and the luminescent centers--rare earth ions--in one of the most efficient luminescence upconversion nanosystems--NaYF4. Specifically, the surface quenching centers, the surface related luminescent centers, as well as the role of shell properties, are investigated spectroscopically. Our results demonstrate that the surface related high-frequency vibrational modes can be critical to the spectral properties of the nanosystems once the surface is not well separated from the discrete luminescent centers.
Journal of Nanoscience and Nanotechnology 11/2010; 10(11):7149-53. · 1.56 Impact Factor
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ABSTRACT: The green emission semiconductor CdSe quantum dots are successfully encapsulated with lecithoid molecules and transferred into aqueous solution. The liposome-encapsulated CdSe maintain similar emission spectrum properties to free CdSe quantum dots. Fluorescence thermal antiquenching is investigated for the liposome-encapsulated CdSe when the temperature is increased from 20 degrees C to 80 degrees C. The reason of the fluorescence enhancement with increasing the temperature is that the vesicle structure of liposome-encapsulated CdSe becomes the CdSe micell structure over the phase transition temperature of the liposome vesicles, and the corresponding structure variation inducing surface reconstruction of CdSe quantum dots.
Journal of Nanoscience and Nanotechnology 11/2010; 10(11):7311-5. · 1.56 Impact Factor
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Berichte der deutschen chemischen Gesellschaft 10/2010; 2010(33):5195 - 5199. · 2.94 Impact Factor
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ABSTRACT: This paper reports the fabrication of a bi-protein/layered double hydroxide (LDH) ultrathin film in which hemoglobin (HB) and horseradish peroxidase (HRP) molecules were assembled alternately with LDH nanosheets via the layer-by-layer (LBL) deposition technique, and its electrocatalytic performances for oxidation of catechol were demonstrated. The results of XRD indicate that the HB-HRP/LDH ultrathin film possesses a long range stacking order in the normal direction of the substrate, with the two proteins accommodated in the LDH gallery respectively as monolayer arrangement. SEM images show that the film surface exhibits a continuous and uniform morphology, and AFM reveals the Root-Mean-Square (RMS) roughness of ∼10.2 nm for the film. A stable direct electrochemical redox behavior of the proteins was successfully obtained for the HB-HRP/LDH film modified electrode. In addition, it exhibits remarkable electrocatalytic activity towards oxidation of catechol, based on the synergistic effect of the two proteins. The catechol biosensor in this work displays a wide linear response range (6-170 μM, r=0.999), low detection limit (5 μM), high sensitivity and good reproducibility.
Biosensors & bioelectronics 10/2010; 26(2):549-54. · 5.43 Impact Factor
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ABSTRACT: Tailor-designed Au/SiO(2) core/shell nanoparticles are employed to enhance the efficiency of fluorescence resonance energy transfer based on quantum dots and R-phycoerythrin in solution.
Chemical Communications 09/2010; 46(35):6479-81. · 6.17 Impact Factor
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ABSTRACT: Highly sensitive, multi-analyte assay is a long-standing challenge for a single fiber-optic evanescent wave biosensor (FOB). In this paper, we report the first realization of such kind of FOB using CdSe/ZnS core/shell quantum dots (QDs) as labels. A direct binding assay model between antibody and antigen was employed to demonstrate the advantages of using QDs, instead of conventional fluorescein isothiocyanate (FITC), in lifting the sensitivity. Especially, multiplexed immunoassay was demonstrated in a single fiber FOB constructed with four differently sized QDs. Furthermore, the phenomenon that the affinity of the QD-labeled human IgG (QD-IgG) with goat anti-human IgG (anti-IgG) was lower than that of the FITC-labeled human IgG (FITC-IgG) was investigated and was ascribed to the differences in size and mass of the two. Our study indicates that the affinity could be improved by controlling the amount of IgG binding on QDs.
Biosensors & bioelectronics 09/2010; 26(1):149-54. · 5.43 Impact Factor
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ABSTRACT: To design more effective CIEEL (chemically initiated electron exchange luminescence) systems demands a complete picture of the dynamics of the chemiluminescence, which is often a challenge. In this work, photoluminescence of the methyl m-oxybenzoate anion - the authentic emitter of AMPPD (3-[2-spiroadamantane]-4-methoxy-4-[3-phosphoryloxy]-phenyl-1,2-dioxetane) in aqueous solvent has been studied. Combining the effect of solvent properties, e.g. pH value, and spectroscopic studies employing steady-state and ultrafast time-resolved emission and absorption and (1)H NMR techniques, a novel mechanism is proposed. We conclude that the deviation of emission peaks between chemiluminescence and photoluminescence of the authentic emitter of AMPPD i.e. the methyl m-oxybenzoate anion, in alkaline aqueous solvents is due to its hydrolysis, rather than the hydrogen-bonding effect as has been assumed so far. Besides, the hydrogen-bonding is suggested to play a key role in significantly decreasing the chemiluminescence yield of AMPPD in aqueous solution by shortening the lifetime of the excited authentic emitter to 10 ps order of magnitude - three orders of magnitude shorter than the previously reported value ( approximately 10 ns). These results shed light on the chemiluminescence dynamics of AMPPD and facilitate the design of more effective CIEEL systems.
Physical Chemistry Chemical Physics 07/2010; 12(25):6789-94. · 3.57 Impact Factor
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Junwei Zhao,
Xiaomin Liu,
Di Cui,
Yajuan Sun,
Yi Yu,
Yifei Yang,
Chuang Du,
Yu Wang,
Kai Song,
Kai Liu,
Shaozhe Lu, Xianggui Kong,
Hong Zhang
Berichte der deutschen chemischen Gesellschaft 03/2010; 2010(12):1813 - 1819. · 2.94 Impact Factor
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ABSTRACT: Water-soluble pure hexagonal-phase NaYF(4):Yb(3+),Er(3+)/Tm(3+) nanoparticles were obtained by an ionothermal method for the first time which offers a new alternative in synthesizing such materials.
Chemical Communications 11/2009; · 6.17 Impact Factor
