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1.
HongCheng Li WenRu Luo Yong Tao Yuan Wu XueFei Lv QunFang Zhou GuiBin Jiang 《中国科学B辑(英文版)》2009,52(10):1683-1690
Quantum dots (QDs) have more and more attention as a novel example of nanocrystals due to their unique fluorescent characteristics.
Recently, the toxicity and the potential environmental effects of QDs have become a research hotspot. In this work, in vivo endocrine disrupting effect, toxicokinetics and oxidative stress of QDs were characterized following the intraperitoneal
dosing in Chinese loaches. Vitellogenin (Vtg) levels induced by E2 decreased significantly when administrated with the mixture
of QDs and E2, which was consistent with the observations of histopathology in testes. The release of free Cd2+ from QDs and the non-specific adsorption of E2 by QDs might be the joint factors contributing to the inhibition of Vtg expression
induced by E2 in the male Chinese loaches. In the muscle, bone, intestines, blood and testis, CdSe QDs reached the maximal
concentration (C
max) in approximately 1-h postinjection and subsequently presented downtrend with the prolonged time. Whereas, there were even
increasing tendencies of CdSe QDs’ concentrations in the liver and kidney. It is educible that CdSe QDs can be persistent
at least for 7 days, indicating the overall half-life of CdSe QDs in the fish body is very long. The measurement of hepatic
superoxide dismutase (SOD) activity and reduced glutathione (GSH) content indicate that QDs have smaller effects on the antioxidative
system of the organisms compared with free Cd2+ due to the effective prevention of the release of Cd by PEG coating of QDs. The comprehensive evaluation of QDs’ toxicity
in the present study provides an essential and general framework towards more focused research on the elucidation of the biological
effects of QDs in vivo. 相似文献
2.
É. I. Zen’kevich Th. Blaudeck M. Heidernätsch F. Cichos C. von Borczyskowski 《Theoretical and Experimental Chemistry》2009,45(1):23-34
The quenching of photoluminescence (PL) in semiconducting CdSe/ZnS and CdSe nanocrystals (NC) of various sizes during surface
passivation by molecules of tetrapyridylporphyrins (P) in toluene at 295 K was investigated. It was shown that resonance transfer
of energy NC → P plays a minor role in PL quenching (<10%), while photoinduced electron transfer NC → P is absent. On the
basis of experimental data and quantum-mechanical calculations it was established that with identical molar ratio x = CP/CNC the probability of quenching k
q
decreases with increase in the size of the NC while the PL quenching process itself under conditions of quantum confinement
is due to electron tunneling of the excited electron–hole pair on the surface of the NC followed by localization of the organic
ligand (P) on anchor groups. The obtained results are of interest for investigating the mechanisms of the blinking of PL in
single semiconductor nanocrystals.
Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 45, No. 1, pp. 17–26, January–February, 2009. 相似文献
3.
Ai-Ling Sun Wen-Wen Mu Yan-Mo Li Ya-Lei Sun Peng-Xiao Li Ren-Min Liu Jie Yang Guo-Yun Liu 《Molecules (Basel, Switzerland)》2021,26(11)
Chemotherapeutic agents, which contain the Michael acceptor, are potent anticancer molecules by promoting intracellular reactive oxygen species (ROS) generation. In this study, we synthesized a panel of PL (piperlongumine) analogs with chlorine attaching at C2 and an electron-withdrawing/electron-donating group attaching to the aromatic ring. The results displayed that the strong electrophilicity group at the C2–C3 double bond of PL analogs plays an important role in the cytotoxicity whereas the electric effect of substituents, which attached to the aromatic ring, partly contributed to the anticancer activity. Moreover, the protein containing sulfydryl or seleno, such as TrxR, could be irreversibly inhibited by the C2–C3 double bond of PL analogs, and boost intracellular ROS generation. Then, the ROS accumulation could disrupt the redox balance, induce lipid peroxidation, lead to the loss of MMP (Mitochondrial Membrane Potential), and ultimately result in cell cycle arrest and A549 cell line death. In conclusion, PL analogs could induce in vitro cancer apoptosis through the inhibition of TrxR and ROS accumulation. 相似文献
4.
Semiconductor quantum dots and metal nanoparticles: syntheses,optical properties,and biological applications 总被引:1,自引:0,他引:1
Biju V Itoh T Anas A Sujith A Ishikawa M 《Analytical and bioanalytical chemistry》2008,391(7):2469-2495
We review the syntheses, optical properties, and biological applications of cadmium selenide (CdSe) and cadmium selenide–zinc
sulfide (CdSe–ZnS) quantum dots (QDs) and gold (Au) and silver (Ag) nanoparticles (NPs). Specifically, we selected the syntheses
of QDs and Au and Ag NPs in aqueous and organic phases, size- and shape-dependent photoluminescence (PL) of QDs and plasmon
of metal NPs, and their bioimaging applications. The PL properties of QDs are discussed with reference to their band gap structure
and various electronic transitions, relations of PL and photoactivated PL with surface defects, and blinking of single QDs.
Optical properties of Ag and Au NPs are discussed with reference to their size- and shape-dependent surface plasmon bands,
electron dynamics and relaxation, and surface-enhanced Raman scattering (SERS). The bioimaging applications are discussed
with reference to in vitro and in vivo imaging of live cells, and in vivo imaging of cancers, tumor vasculature, and lymph
nodes. Other aspects of the review are in vivo deep tissue imaging, multiphoton excitation, NIR fluorescence and SERS imaging,
and toxic effects of NPs and their clearance from the body.
Figure Semiconductor quantum dots and metal nanoparticles have extensive applications, e.g., in vitro and in vivo bioimaging
Tamitake Itoh and Abdulaziz Anas contributed equally to this article. 相似文献
5.
Eimo Kin Takeshi Fukuda Sayaka Kato Zentaro Honda Norihiko Kamata 《Journal of Sol-Gel Science and Technology》2009,50(3):409-414
In order to improve the stability of red phosphor with efficient and high color-purity characteristics under ultraviolet excitation,
we encapsulated Eu(TTA)3phen(tris(2-thenoyltrifluoroacetonato)(1,10-phenanthroline)europium(III)) by sol–gel derived silica glasses and studied their
photoluminescence (PL) characteristics. The dependence of pH values in the starting solution revealed that the process condition
should be within the modest region with the optimum pH value around 6–7. The PL intensity increased with increasing the concentration
of Eu(TTA)3phen initially, then it showed saturating tendency above 0.6 mol%. An improvement of reliability by the glass encapsulation
was exemplified by monitoring the long-term PL intensity under constant UV irradiation. We consider that the glass network
carefully prepared by sol–gel process is effective for preventing free oxygen and water from attacking Eu(TTA)3phen molecule without loss of PL output. 相似文献
6.
Pietryga JM Schaller RD Werder D Stewart MH Klimov VI Hollingsworth JA 《Journal of the American Chemical Society》2004,126(38):11752-11753
Efficient mid-infrared sources are of considerable general interest for gas analysis, remote sensing, and atmospheric monitoring, but existing technologies are limited. Here, we report the synthesis of the first colloidal QDs having photoluminescence (PL) in the mid-infrared. We show particle-size-tunable mid-infrared emission for large (10-17 nm), but quantum-confined, colloidal PbSe QDs, with efficient, narrow-bandwidth PL at energies as low as 0.30 eV (4.1 mum). Applying two new synthetic routes, we have achieved fine control of QD size and size distribution, allowing us to provide the first systematic correlation of QD size with PL energy for PbSe QDs emitting at wavelengths longer than 2 mum, results which are compared with a literature model. For the entire spectral range reported, we provide measured quantum yields in emission, showing a marked decrease with increasing QD size, for which we include a possible explanation. Finally, we present very promising preliminary results for overcoating PbSe with CdSe, a wider-gap semiconductor. We show PL enhanced by approximately 6-fold for such core/shell samples. 相似文献
7.
As a new type of carbon-based fluorescent nanomaterials, carbon dots(CDs) are provided with the advantages of small size, excellent photoluminescence(PL) property, easy surface modification, robust stability,good water solubility and biocompatibility, which endow them with great potential in sensing. In this review, we first describe the preparation of CDs from different starting materials via various techniques, and pre-/post-modification strategies to modulate their PL properties. Second, we o... 相似文献
8.
Herein we report that boron doping in carbon dots results in increased photoluminescence (PL) quantum yield, which could be used for ratiometric intracellular pH sensing in cancer cell lines. Using a mixture of citric acid monohydrate, thiourea, and boric acid, microwave-assisted synthesis of boron doped blue emitting carbon dots (B-Cdots) with an average size of 3.5±1.0 nm was achieved. For B-Cdots, the maximum quantum yield (QY) was observed to be 25.8 % (11.1 % (w/w) H3BO3 input concentration), whereas, the same was calculated to be 16.9 % and 11.4 % for Cdots (synthesized from citric acid monohydrate and thiourea only) and P-Cdots (phosphorus doped carbon dots; synthesized using citric acid monohydrate, thiourea and phosphoric acid) (11.1 % (w/w) H3PO4 input concentration), respectively. The observed luminescence efficiencies as obtained from steady state and time-resolved photoluminescence measurements suggest an alternative emission mechanism due to boron/phosphorus doping in carbon dots. We furthermore demonstrated facile composite formation using B-Cdots and another carbon dots with orange emission in presence of polyvinyl alcohol (PVA), resulting in white light emission (0.31, 0.32; λex 380 nm). The white light emitting composite enabled ratiometric pH sensing in the aqueous medium and showed favorable uptake properties by cancerous cells for intracellular pH sensing as well. 相似文献
9.
Struss AK Pasini P Flomenhoft D Shashidhar H Daunert S 《Analytical and bioanalytical chemistry》2012,402(10):3227-3236
Quorum sensing (QS) allows bacteria to communicate with one another by means of QS signaling molecules and control certain
behaviors in a group-based manner, including pathogenicity and biofilm formation. Bacterial gut microflora may play a role
in inflammatory bowel disease pathogenesis, and antibiotics are one of the available therapeutic options for Crohn’s disease.
In the present study, we employed genetically engineered bioluminescent bacterial whole-cell sensing systems as a tool to
evaluate the ability of antibiotics commonly employed in the treatment of chronic inflammatory conditions to interfere with
QS. We investigated the effect of ciprofloxacin, metronidazole, and tinidazole on quorum sensing. Several concentrations of
individual antibiotics were allowed to interact with two different types of bacterial sensing cells, in both the presence
and absence of a fixed concentration of N-acylhomoserine lactone (AHL) QS molecules. The antibiotic effect was then determined by monitoring the biosensor’s bioluminescence
response. Ciprofloxacin, metronidazole, and tinidazole exhibited a dose-dependent augmentation in the response of both bacterial
sensing systems, thus showing an AHL-like effect. Additionally, such an augmentation was observed, in both the presence and
absence of AHL. The data obtained indicate that ciprofloxacin, metronidazole, and tinidazole may interfere with bacterial
communication systems. The results suggest that these antibiotics, at the concentrations tested, may themselves act as bacterial
signaling molecules. The beneficial effect of these antibiotics in the treatment of intestinal inflammation may be due, at
least in part, to their effect on QS-related bacterial behavior in the gut. 相似文献
10.
Weipan Cui Rui Liu Eeshita Manna Joong-Mok Park Fadzai Fungura Joseph Shinar Ruth Shinar 《Analytica chimica acta》2015
Approaches to generate porous or doped sensing films, which significantly enhance the photoluminescence (PL) of oxygen optical sensors, and thus improve the signal-to-noise (S/N) ratio, are presented. Tailored films, which enable monitoring the relative humidity (RH) as well, are also presented. Effective porous structures, in which the O2-sensitive dye Pt octaethylporphyrin (PtOEP) or the Pd analog PdOEP was embedded, were realized by first generating blend films of polyethylene glycol (PEG) with polystyrene (PS) or with ethyl cellulose (EC), and then immersing the dried films in water to remove the water-soluble PEG. This approach creates pores (voids) in the sensing films. The dielectric contrast between the films’ constituents and the voids increases photon scattering, which in turn increases the optical path of the excitation light within the film, and hence light absorption by the dye, and its PL. Optimized sensing films with a PEG:PS ratio of 1:4 (PEG’s molecular weight Mw ∼8000) led to ∼4.4× enhancement in the PL (in comparison to PS films). Lower Mw ∼200 PEG with a PEG:EC ratio of 1:1 led to a PL enhancement of ∼4.7×. Film-dependent PL enhancements were observed at all oxygen concentrations. The strong PL enhancement enables (i) using lower dye (luminophore) concentrations, (ii) reducing power consumption and enhancing the sensor’s operational lifetime when using organic light emitting diodes (OLEDs) as excitation sources, (iii) improving performance when using compact photodetectors with no internal gain, and (iv) reliably extending the dynamic range. 相似文献
11.
Yuanjing Cui Jiancan Yu Junkuo Gao Zhiyu Wang Guodong Qian 《Journal of Sol-Gel Science and Technology》2009,52(3):362-369
A DCM derivative, namely 4-Dicyanomethylene-2-methyl-6-{[4′-(N-hydroxyethyl-N-methyl)amino]styryl}-4H-pyran (DCMH), has been synthesized and covalently incorporated into the inorganic silica network as pendants via a sol–gel process. Molecular
structures of the resultants are confirmed by elemental analysis, 1H NMR, DSC, TGA, FTIR and UV–Vis spectroscopy. Photoluminescence (PL) spectra shows that the emission of DCMH peaked at 625 nm is almost completely quenched in DMF solution with a concentration of 1 × 10−4 mol/L, however, in hybrid films, the PL intensity enhances obviously with increasing DCMH concentration even at the high loading content of 40 mol%. All the hybrid films exhibit PL emission around 646–650 nm and
the peak position reveal little dependence on the concentration of dye, suggesting they can be used as red emissive materials
in light-emitting diodes. The relationship between fluorescence lifetime and dye concentration is also investigated by time-resolved
PL measurements. 相似文献
12.
Qualitative and quantitative profiling of six different categories of urinary phospholipids (PLs) from patients with prostate
cancer was performed to develop an analytical method for the discovery of candidate biomarkers by shotgun lipidomics method.
Using nanoflow liquid chromatography–electrospray ionization–tandem mass spectrometry, we identified the molecular structures
of a total of 70 PL molecules (21 phosphatidylcholines (PCs), 11 phosphatidylethanolamines (PEs), 17 phosphatidylserines (PSs),
11 phosphatidylinositols (PIs), seven phosphatidic acids, and three phosphatidylglycerols) from urine samples of healthy controls
and prostate cancer patients by data-dependent collision-induced dissociation. Identified molecules were quantitatively examined
by comparing the MS peak areas. From statistical analyses, one PC, one PE, six PSs, and two PIs among the PL species showed
significant differences between controls and cancer patients (p < 0.05, Student’s t test), with concentration changes of more than threefold. Cluster analysis of both control and patient groups showed that
18:0/18:1-PS and 16:0/22:6-PS were 99% similar in upregulation and that the two PSs (18:1/18:0, 18:0/20:5) with two PIs (18:0/18:1
and 16:1/20:2) showed similar (>95%) downregulation. The total amount of each PL group was compared among prostate cancer
patients according to the Gleason scale as larger or smaller than 6. It proposes that the current study can be utilized to
sort out possible diagnostic biomarkers of prostate cancer. 相似文献
13.
A convergent building block synthesis has been applied to new off/on photoinduced electron transfer (PET) modulated fluorescent sensors which are based on a BF(2) chelated tetraarylazadipyrromethene platform and operate in the biomedically important red region of the visible spectrum. Incorporation of diethylamine and morpholine receptors facilitates off/on microenvironment polarity and pH sensing. Aqueous formulation and in vitro cellular imaging demonstrates their potential for intracellular sensing. 相似文献
14.
Raw and thermally treated sepiolites from the Mantoudi area, Euboea, Greece, were investigated by means of X-ray diffraction
(XRD) in combination with thermo-gravimetric analysis (TG/DTG) and differential thermal analysis (DTA), as well as Fourier
transform (FTIR) spectroscopy, in order to study the collapse of the sepiolite structure with increasing temperature. The
main mineral constituent (>95%) is a well crystallized sepiolite. Quartz and dolomite occur in minor amounts. Calcination
of the samples was carried out up to 350, 720 and 820°C, for 2 h, and ‘sepiolite dihydrite’, ‘sepiolite anhydrite’ and ‘enstatite’
were formed, respectively, as magnesium co-ordinated water and octahedrically co-ordinated hydroxyl groups, are removed and
the dehydroxylated phase recrystallize to enstatite (MgSiO3). These structural and textural changes play an important role to the properties and uses of the studied sepiolites. 相似文献
15.
Silica-coated magnetic polystyrene nanospheres (MPN) containing CdTe/CdS quantum dots (QDs) and Fe3O4 nanoparticles were prepared, and novel anti-EGFR antibodies were conjugated onto these magneto-fluorescent nanocomposites
(MPN–QDs–SiO2) for cancer cell targeting, imaging and collection. Transmission electron microscopy (TEM), scanning electron microscopy
(SEM) images and energy-dispersive x-ray spectrometry (EDS) data showed that the MPN had been successfully coated with QDs
and a silica shell, and the nanocomposites obtained with negative charged surfaces were well dispersed. The bioconjugates
could be used for specifically labeling and separating cancer cells (MDA-MB-435S, SMMC-7721), but did not recognize and separate
the K562 cells because the human epidermal growth factor receptor (EGFR) was not expressed on the surface. Because the anti-EGFR
antibody, which we have developed, could specifically recognize certain cancer cells that highly expressed EGFR on their surface,
these nanoscale bioconjugates, synchronously exhibiting fluorescence and magnetism, may be used in novel bioprobes for labeling
and collecting rare cancer cells, which may be beneficial for early cancer diagnosis. 相似文献
16.
High sensitivity sensing of nitroaromatic explosive vapors based on polytriphenylamines with AIE‐active tetraphenylethylene side groups
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Wenyue Dong Yuyu Pan Martin Fritsch Ullrich Scherf 《Journal of polymer science. Part A, Polymer chemistry》2015,53(15):1753-1761
Two polytriphenylamines (PTPAs) (P1 and P2) with aggregation induced emission (AIE)‐active tetraphenylethylene side groups have been designed and successfully synthesized. Both polymers only faintly emit in dilute solution but show strong emission in aggregated state, meaning that they are AIE‐active. The detection of 1,3,5‐trinitrobenzene (TNB) vapors has been investigated by photoluminescence (PL) quenching in polymer films. High solid state quantum yields and donor‐acceptor interactions of the electron‐rich PTPA chains with the TNB analyte, hereby, induce a high sensing sensitivity, both for P1 and P2 films towards TNB vapor. Contacting thin P1 and P2 films with saturated TNB vapor, the PL intensity was quenched by 85% for P1 and 89% for P2 within 600 s, respectively. The sensing process is reversible, >90% of the PL is recovered, also after repeated cycling. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 53, 1753–1761 相似文献
17.
Over the last few decades there has been a strong decrease in the number of Thermal Analysis and Calorimetry (TA and C) ‘practitioners’
- scientists who know the in sand outs of TA and C and its (im)possibilities and are capable of initiating new developments.
By contrast, an increasing number of TA and C ‘users’ are scarcely able to acquire in-depth knowledge of TA and C. It is therefore
of great importance that national TA and C societies create the infrastructure for dedicated education. In addition, the feasibility
of setting up one or more expertise centers per country, where ‘practitioners’ can do research,carry out contract research
and give advice to users, needs to be investigated.
Equally important, the TA and C community needs to address a number of challenges in the coming decade with the aim of controlling
the ‘knowledge cycle’ in the field of polymers: to translate non-optimal properties into improved processing conditions or
even a more suitable macromolecular architecture, in order to reduce the lead times for the development and optimization of
materials.
Although Thermal Analysis and Calorimetry can generally be considered to be ‘mature’, in specific subareas a large number
of new developments take place. A few examples of these developments and of state-of-the-art TA and C are given:quantitative
heat capacity measurements by means of DSC; (very) high pressure DSC;real-time morphological analysis and temperature-modulated
X-ray analysis. In addition, anew form of TA and C is discussed: High Performance DSC (HPer DSC), which is also a high rate
DSC and a high throughput DSC.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
18.
Yow-Jon Lin Chia-Lung Tsai Chia-Jyi Liu Lance Horng Yu-Tai Shih Mu-Shan Wang Chuan-Sheng Jhang Chao-Shien Huang 《Journal of Sol-Gel Science and Technology》2009,52(1):109-112
Co0.2Mg
x
Zn0.8−x
O films prepared with different molar ratio of magnesium acetate to zinc acetate were deposited on substrates by the sol–gel
technique. X-ray diffraction, photoluminescence (PL) and ferromagnetism measurements were used to characterize the Co0.2Mg
x
Zn0.8−x
O diluted magnetic semiconductors. The acceptor-like defects were determined in the PL band and the intensity of the acceptor-related
PL increased with increasing Mg concentration. Therefore, an increase in the number of the acceptor-like defects (zinc vacancies
especially) in the Co0.2Mg
x
Zn0.8−x
O film may lead to the enhancement of the magnetic properties. It is worth noting that changes in Mg concentration and the
number of the acceptor-like defects are important issues for producing strong ferromagnetism Co0.2Mg
x
Zn0.8−x
O films prepared by the sol–gel method. 相似文献
19.
本文以NBD-NH2荧光团偶联N-(4-吡啶甲基)乙二胺质子受体构建了基于光致电子转移(PET)机制的pH探针NBD-Py。探针在pH 5.0~8.5范围内显示pH降低导致的荧光增强响应,pKa为6.48。该响应不受胞内常见金属离子干扰且有良好的可逆性。研究表明质子受体中引入4-甲基吡啶修饰乙二胺是探针实现对弱酸/近中性pH响应的关键。HeLa细胞中的造影证实了探针的pHi造影能力和溶酶体靶向性能,为溶酶体pH相关的生理过程研究提供了新的可靠手段。 相似文献
20.
P. M. Chu G. C. Rhoderick D. Van Vlack S. J. Wetzel W. J. Lafferty F. R. Guenther 《Analytical and bioanalytical chemistry》1998,360(3-4):426-429
Open-path monitoring of the atmosphere using Fourier transform infrared spectrometry has recently become a useful real-time
in situ analytical technique. The U.S. Environmental Protection Agency (EPA) is currently formulating Method TO-16, a protocol
for infrared remote sensing of the hazardous air pollutants (HAPs) identified in EPA’s Clean Air Act of 1990. To support infrared
based sensing technologies, the National Institute of Standards and Technology (NIST) is currently developing a standard quantitative
spectral database of the HAPs based on gravimetrically prepared samples. This paper presents the protocol used to prepare
the gravimetric mixtures and initial results.
Received: 6 June 1997 / Revised: 4 August 1997 / Accepted: 7 August 1997 相似文献