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31.
32.
Srivastava S Ball V Podsiadlo P Lee J Ho P Kotov NA 《Journal of the American Chemical Society》2008,130(12):3748-3749
The exponentially growing layer-by-layer (LBL) films made from poly(diallyldimethylammonium chloride) (PDDA) and poly(acrylic acid) (PAA) were used to load and unload the CdTe nanoparticles (NPs). The reversible loading of NPs were investigated through UV-vis studies and further confirmed by confocal microscopy. In addition the LBL films were also compared for the release kinetics for pH 9 and 7 and films capped with (PDDA-PSS)10 layers. The amount of released particles at pH 9 was found to be at least 2 orders of magnitude higher than those at pH 7 and with (PDDA-PSS)10 capped layers after 25 h. This variation in film response for CdTe-particle release presents a route for studies in which highly swollen exponentially growing LBL films can be loaded with functionalized NPs for biological applications and explored as carriers to hold the NPs inside the films for self-assembly. 相似文献
33.
Podsiadlo P Sinani VA Bahng JH Kam NW Lee J Kotov NA 《Langmuir : the ACS journal of surfaces and colloids》2008,24(2):568-574
6-mercaptopurine and its riboside derivatives are some of the most widely utilized anti-leukemic and anti-inflammatory drugs. Their short biological half-life and severe side effects limit their use. A new delivery method for these drugs based on 4-5 nm gold nanoparticles can potentially resolve these issues. We have found substantial enhancement of the antiproliferative effect against K-562 leukemia cells of Au nanoparticles bearing 6-mercaptopurine-9-beta-d-ribofuranoside compared to the same drug in typically administered free form. The improvement was attributed to enhanced intracellular transport followed by the subsequent release in lysosomes. Enhanced activity and nanoparticle carriers will make possible the reduction of the overall concentration of the drug, renal clearance, and, thus, side effects. The nanoparticles with mercaptopurine also showed excellent stability over 1 year without loss of inhibitory activity. 相似文献
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Podsiadlo P Paternel S Rouillard JM Zhang Z Lee J Lee JW Gulari E Kotov NA 《Langmuir : the ACS journal of surfaces and colloids》2005,21(25):11915-11921
In a recent report, we have presented the layer-by-layer (LBL) assembly of a biomimetic nanostructured composite from Na(+)-montmorillonite clay nanosheets and poly(diallylmethylammonium chloride) (Tang, Z.; Kotov, N.; Magonov, S.; Ozturk, B. Nat. Mater. 2003, 2, 413). The structure, deformation mechanism, and mechanical properties of the material are very similar to those of natural nacre and lamellar bones. This fact prompts further investigation of these composites as potential bone implants. LBL assembly affords preparation of multifunctional composites, and here we demonstrate that not only mechanical strength, but also antibacterial activity, can be introduced in these implantable materials by alternating clay layers with starch-stabilized silver nanoparticles. The resulting composite showed excellent structural stability with no detectable levels of silver lost over a 1 month period. Evaluation of the antibacterial properties showed almost complete growth inhibition of E. coli over an 18 h period. The amount of silver eluted from the LBL composite over a 1 month period was determined to be only 0.5-3.0 microg/L. This concentration of silver did not prevent the growth of the mammalian tissue cultures. The LBL composite has shown biocompatibility with the human osteoblast cell line. 相似文献
36.
Sara Abalde‐Cela Szushen Ho Benito Rodríguez‐González Dr. Miguel A. Correa‐Duarte Dr. Ramón A. Álvarez‐Puebla Dr. Luis M. Liz‐Marzán Prof. Nicholas A. Kotov Prof. 《Angewandte Chemie (International ed. in English)》2009,48(29):5326-5329
Feature film : Thin films made by exponential layer‐by‐layer growth display high diffusivity and can be readily infiltrated with inorganic nanoparticles. They can sequestrate molecular systems from solution as a function of the composition of their layers, while providing intense surface‐enhanced Raman scattering (SERS) signals (see picture).
37.
Zexi Liu Jing Ai Prashant Kumar Enming You Xiong Zhou Xi Liu Zhongqun Tian Petr Bou Yingying Duan Lu Han Nicholas A. Kotov Songyuan Ding Shunai Che 《Angewandte Chemie (International ed. in English)》2020,59(35):15226-15231
A surface‐enhanced Raman scattering‐chiral anisotropy (SERS‐ChA) effect is reported that combines chiral discrimination and surface Raman scattering enhancement on chiral nanostructured Au films (CNAFs) equipped in the normal Raman scattering Spectrometer. The CNAFs provided remarkably higher enhancement factors of Raman scattering (EFs) for particular enantiomers, and the SERS intensity was proportional to the enantiomeric excesses (ee) values. Except for molecules with mesomeric species, all of the tested enantiomers exhibited high SERS‐ChA asymmetry factors (g), ranging between 1.34 and 1.99 regardless of polarities, sizes, chromophores, concentrations and ee. The effect might be attributed to selective resonance coupling between the induced electric and magnetic dipoles associated with enantiomers and chiral plasmonic modes of CNAFs. 相似文献
38.
S.?G.?Barsov S.?I.?Vorob’ev E.?I.?Golovenchits A.?A.?Dzyuba E.?N.?Komarov V.?P.?Koptev S.?A.?Kotov V.?A.?Sanina G.?V.?Shcherbakov 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(5):705-707
The present paper is devoted to studying the multiferroics HoMnO3, YMnO3, EuMn2O5, and GdMn2O5 by means of the µSR-method. Determination of the dynamic relaxation parameter 7n and the distribution of the local magnetic fields results in a clear phase diagram. 相似文献
39.
St. Kotov 《Journal of inclusion phenomena and macrocyclic chemistry》2010,68(3-4):485-491
The effect of N7 protonation on the IR-spectroscopic characteristics in solid-state and aromatic character of 7-azaindole (7AI) are elucidated by means of linear-polarized IR-spectroscopy of oriented colloids in nematic host. A comparison between the data of neutral and protonated form of 7AI is done. The experimental data are supported by theoretical ab initio ones and experimental UV-spectroscopic measurements. 相似文献
40.
The kinetic relations holding in nucleophilic replacement of hydrogen in para-substituted nitrobenzenes by phenylacetonitrile carbanion suggest a complex reaction mechanism involving two alternative pathways. The direction of the process is determined by the structure of intermediate -complex. 相似文献