排序方式: 共有70条查询结果,搜索用时 15 毫秒
31.
Avidin: a natural bridge for quantum dot-antibody conjugates 总被引:20,自引:0,他引:20
Goldman ER Balighian ED Mattoussi H Kuno MK Mauro JM Tran PT Anderson GP 《Journal of the American Chemical Society》2002,124(22):6378-6382
We describe the preparation and characterization of bioinorganic conjugates in which luminescent semiconductor CdSe-ZnS core-shell nanocrystal quantum dots (QDs) were coupled to antibodies through the use of an avidin bridge adsorbed to the nanocrystal surface via electrostatic self-assembly. Avidin, a highly positively charged protein, was found to adsorb tightly to QDs modified with dihydrolipoic acid, which gives their surface a homogeneous negative charge. QD conjugation to biotinylated antibodies subsequently is readily achieved. Fluoroimmunoassays utilizing these antibody conjugated QDs were successful in the detection of protein toxins (staphylococcal enterotoxin B, cholera toxin). QD-antibody conjugates formed in such a facile manner permit their use as a common immuno reagent, and in the development of multianalyte detection. 相似文献
32.
New derivatives of 4-amino [3,4-d] pyrazolo pyrimidine have been prepared. Mono, di- and tri-substitution products are characterised by unequivocal synthesis. Several compounds are being tested for possible carcinostatic activity. 相似文献
33.
We give explicit upper bounds for linear trigonometric sums over primes.
34.
Ji X Palui G Avellini T Na HB Yi C Knappenberger KL Mattoussi H 《Journal of the American Chemical Society》2012,134(13):6006-6017
We investigated the charge transfer interactions between luminescent quantum dots (QDs) and redox active dopamine. For this, we used pH-insensitive ZnS-overcoated CdSe QDs rendered water-compatible using poly (ethylene glycol)-appended dihydrolipoic acid (DHLA-PEG), where a fraction of the ligands was amine-terminated to allow for controlled coupling of dopamine-isothiocyanate onto the nanocrystal. Using this sample configuration, we probed the effects of changing the density of dopamine and the buffer pH on the fluorescence properties of these conjugates. Using steady-state and time-resolved fluorescence, we measured a pronounced pH-dependent photoluminescence (PL) quenching for all QD-dopamine assemblies. Several parameters affect the PL loss. First, the quenching efficiency strongly depends on the number of dopamines per QD-conjugate. Second, the quenching efficiency is substantially increased in alkaline buffers. Third, this pH-dependent PL loss can be completely eliminated when oxygen-depleted buffers are used, indicating that oxygen plays a crucial role in the redox activity of dopamine. We attribute these findings to charge transfer interactions between QDs and mainly two forms of dopamine: the reduced catechol and oxidized quinone. As the pH of the dispersions is changed from acidic to basic, oxygen-catalyzed transformation progressively reduces the dopamine potential for oxidation and shifts the equilibrium toward increased concentration of quinones. Thus, in a conjugate, a QD can simultaneously interact with quinones (electron acceptors) and catechols (electron donors), producing pH-dependent PL quenching combined with shortening of the exciton lifetime. This also alters the recombination kinetics of the electron and hole of photoexcited QDs. Transient absorption measurements that probed intraband transitions supported those findings where a simultaneous pronounced change in the electron and hole relaxation rates was measured when the pH was changed from acidic to alkaline. 相似文献
35.
Javier Pérez‐Pellitero Dr. Hedi Amrouche Flor R. Siperstein Dr. Gerhard Pirngruber Dr. Carlos Nieto‐Draghi Dr. Gérald Chaplais Dr. Angélique Simon‐Masseron Dr. Delphine Bazer‐Bachi Dr. David Peralta Nicolas Bats Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(5):1560-1571
Experimental measurements and molecular simulations were conducted for two zeolitic imidazolate frameworks, ZIF‐8 and ZIF‐76. The transferability of the force field was tested by comparing molecular simulation results of gas adsorption with experimental data available in the literature for other ZIF materials (ZIF‐69). Owing to the good agreement observed between simulation and experimental data, the simulation results can be used to identify preferential adsorption sites, which are located close to the organic linkers. Topological mapping of the potential‐energy surfaces makes it possible to relate the preferential adsorption sites, Henry constant, and isosteric heats of adsorption at zero coverage to the nature of the host–guest interactions and the chemical nature of the organic linker. The role played by the topology of the solid and the organic linkers, instead of the metal sites, upon gas adsorption on zeolite‐like metal–organic frameworks is discussed. 相似文献
36.
Hedi Mighri Hafedh Hajlaoui Ahmed Akrout Hanen Najjaa Mohamed Neffati 《Comptes Rendus Chimie》2010,13(3):380-386
This study was conceived to examine the antimicrobial and antioxidant activities of four essential oil types extracted by hydrodistillation from the aerial parts of Artemisia herba-alba cultivated in southern Tunisia. The chemical composition was investigated using both capillary GC and GC/MS techniques. β-thujone, α-thujone, α-thujone/β-thujone and 1,8-cineole/camphor/α-thujone/β-thujone were respectively, the major components of these oil types. The antimicrobial activity of different oils was tested using the diffusion method and by determining the inhibition zone. The results showed that all examined oil types had great potential of antimicrobial activity against strains. In addition, antioxidant capacity was assessed by different in vitro tests and weak activity was found for these A. herba-alba oils. 相似文献
37.
Abdallah Harizi Hedi Zantour 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):219-229
Abstract A variety of 2-phosphonomethyl N-amidobenzimidazoles and 2-phosphonomethyl N-hydrazidobenzimidazoles has been efficiently synthesized by treatment of 2-phosphonométhyl N-ethoxycarbonylbenzimidazoles respectively with the appropriate prim amines and hydrazines. The structure of these products was confirmed by IR, NMR(1H, 13C, 31P) spectroscopy and mass spectra. 相似文献
38.
Soufiane Touil Hedi Zantour 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2):353-360
The reaction of n , n '-diphosphonylketones 1 with active methylenenitriles and sulfur in basic conditions led to the new 5-amino-2-(phosphonomethyl)-3-(phosphonoethyl)thiophenes 2 . These compounds were then used in the Horner-Wadsworth-Emmons reaction to give 5-amino-2-alkenyl-3-(phosphonoethyl)thiophenes 3 . The structure of all obtained products was confirmed by NMR ( 1 H, 31 P, 13 C) and IR spectroscopy. 相似文献
39.
Heng Lu Xuejuan Zhang Cuihong Li Hedi Wei Qian Liu Weiwei Li Zhishan Bo 《Macromolecular rapid communications》2015,36(14):1348-1353
Performance enhancement of polymer solar cells (PSCs) is achieved by expanding the absorption of the active layer of devices. To better match the spectrum of solar radiation, two polymers with different band gaps are used as the donor material to fabricate ternary polymer cells. Ternary blend PSCs exhibit an enhanced short‐circuit current density and open‐circuit voltage in comparison with the corresponding HD‐PDFC‐DTBT (HD)‐ and DT‐PDPPTPT (DPP)‐based binary polymer solar cells, respectively. Ternary PSCs show a power conversion efficiency (PCE) of 6.71%, surpassing the corresponding binary PSCs. This work demonstrates that the fabrication of ternary PSCs by using two polymers with complementary absorption is an effective way to improve the device performance.
40.
Hedi Benamor 《代数通讯》2013,41(3):715-736
We present a reduction of the adjoint representation of the Lie superalge-bra,sl(2,1) and a study of the quotient algebra B(c,k)= u/u(C?c)+u(D?kc), where c,k are two complex numbers. Under some additional conditions, we prove that every irreducible infinite dimensional representation of B(c,k) is faithful, and that B(C,K) is a primitive algebra. We give explicitly a set of generators of primitive degenerate ideal of infinite codimension. Essentially we prove that any minimal primitive ideal of u(sl(2,1)) is generated, as a 2-sided ideal, by its intersection with the algebra of gg-iuvariants. 相似文献