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81.
Nidhi Andhariya Bhupendra Chudasama R. V. Mehta R. V. Upadhyay 《Journal of nanoparticle research》2011,13(4):1677-1688
The use of nanoparticles as drug delivery systems for anticancer therapeutics has great potential to revolutionize the future
of cancer therapy. The aim of this study is to construct a novel drug delivery platform comprising a magnetic core and biodegradable
thermoresponsive shell of tri-block-copolymer. Oleic acid-coated Fe3O4 nanoparticles and hydrophilic anticancer drug “doxorubicin” are encapsulated with PEO–PLGA–PEO (polyethylene oxide–poly d, l lactide-co-glycolide–polyethylene oxide) tri-block-copolymer. Structural, magnetic, and physical properties of Fe3O4 core are determined by X-ray diffraction, vibrating sample magnetometer, and transmission electron microscopy techniques,
respectively. The hydrodynamic size of composite nanoparticles is determined by dynamic light scattering and is found to be
~36.4 nm at 25 °C. The functionalization of magnetic core with various polymeric chain molecules and their weight proportions
are determined by Fourier transform infrared spectroscopy and thermogravimetric analysis, respectively. Encapsulation of doxorubicin
into the polymeric magnetic nanoparticles, its loading efficiency, and kinetics of drug release are investigated by UV–vis
spectroscopy. The loading efficiency of drug is 89% with a rapid release for the initial 7 h followed by the sustained release
over a period of 36 h. The release of drug is envisaged to occur in response to the physiological temperature by deswelling
of thermoresponsive PEO–PLGA–PEO block-copolymer. This study demonstrates that temperature can be exploited successfully as
an external parameter to control the release of drug. 相似文献
82.
N Tibrewal TE Downey SG Van Lanen E Ul Sharif GA O'Doherty J Rohr 《Journal of the American Chemical Society》2012,134(30):12402-12405
Two enzymes of the gilvocarcin biosynthetic pathway, GilMT and GilM, with unclear functions were investigated by in vitro studies using purified, recombinant enzymes along with synthetically prepared intermediates. The studies revealed GilMT as a typical S-adenosylmethionine (SAM) dependent O-methyltransferase, but GilM was identified as a pivotal enzyme in the pathway that exhibits dual functionality in that it catalyzes a reduction of a quinone intermediate to a hydroquinone, which goes hand-in-hand with a stabilizing O-methylation and a hemiacetal formation. GilM mediates its reductive catalysis through the aid of GilR that provides FADH(2) for the GilM reaction, through which FAD is regenerated for the next catalytic cycle. This unusual synergy eventually completes the biosynthesis of the polyketide-derived defuco-gilvocarcin chromphore. 相似文献
83.
The ground state geometries of [Alanine (Ala) + M2+] [M = Ca, Cu, and Zn) complexes were calculated in gas phase at B3LYP/6‐311++G(d,p) level of theory. Transition states (TSs) between different stable conformers of [Ala + M2+] complexes were also calculated. Among the different [Ala + M2+] complexes, the complex where metal cations coordinated to carboxylate group (? COO?) is found to be energetically most favorable. To calculate TSs, the ground state structures of any two conformers of [Ala + M2+] complexes were used. The ground state energies of two stable conformers and their TS structures were used to calculate the activation energy. The reactivity of different conformers of [Ala + M2+] complexes have been discussed in terms of energy difference between their highest occupied molecular orbital and lowest unoccupied molecular orbital. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012 相似文献
84.
The CdS nanostructure undergoes photochemical dissolution, and hence, the photocatalytic activity deteriorates with light irradiation time. A thin layer of silica coating over CdS surface may prevent the photocorrosion and coalescence of quantum size CdS particles. Hence, we synthesized SiO(2)@CdS nanocomposites of different shapes and characterized them by XRD, HRTEM, EDX, SAED, BET surface area measurement and absorption and emission study. The dispersion of spherical CdS (Cd-2.62 at% and S-2.33 at%) nanoparticles of cubic crystal structure into thick amorphous SiO(2) (43.79 at%) matrix is demonstrated here. The fabrication of core (CdS)-shell (SiO(2)) structure (SiO(2)@CdS) consisting of CdS nanorod (Cd-19.79 at% and S-22.90 at%) core (length ~126 nm and width ~6 nm) having characteristic lattice fringes of hexagonal crystals and thin SiO(2) (12.81 at%) shell (thickness=1-1.4 nm) is successfully achieved for the first time. The surface area (21.2m(2)/g) of CdS nanorod (aspect ratio=21) is found to increase (42.3m(2)/g) after SiO(2) coating. The photoluminescence of CdS nanosphere (485 nm) and nanorod (501 nm) is highly quenched after SiO(2) layer formation. The superior photocatalytic activity of SiO(2)@CdS composites for the benzaldehyde oxidation under UV irradiation has been displayed. 相似文献
85.
86.
Pallavi Dwivedi V. Vivekanand Nidhi Pareek Amit Sharma Rajesh P. Singh 《Applied biochemistry and biotechnology》2010,160(1):255-268
Mixed enzyme preparation having both xylanase and laccase activity was evaluated for its bleach enhancing ability of mixed
wood pulp. The enzyme was produced through co-cultivation of mutant Penicillium oxalicum SAUE-3.510 and Pleurotus ostreatus MTCC 1804 under solid-state fermentation. Bleaching of pulp with mixed enzyme had resulted into a notable decrease in kappa
number and increased brightness as compared to xylanase alone. Analysis of bleaching conditions had denoted that 8 IU g−1 of mixed enzyme preparation (xylanase/laccase, 22:1) had led into maximal removal of lignin from pulp when bleaching was
performed at 10% pulp consistency (55 °C, pH 9.0) for 3 h. An overall improvement of 21%, 8%, 3%, and 5% respectively in kappa
number, brightness, yellowness, and viscosity of pulp was achieved under derived bleaching conditions. Process of enzymatic
bleaching was further ascertained by analyzing the changes occurring in polysaccharide and lignin by HPLC and FTIR. The UV
absorption spectrum of the compounds released during enzymatic treatment had denoted a characteristic peak at 280 nm, indicating
the presence of lignin in released coloring matter. The changes in fiber morphology following enzymatic delignification were
studied by scanning electron microscopy. 相似文献
87.
Nanotechnology can be described as an emerging technology and, as has been the case with other emerging technologies such
as genetic modification, different socio-psychological factors will potentially influence societal responses to its development
and application. These factors will play an important role in how nanotechnology is developed and commercialised. This article
aims to identify expert opinion on factors influencing societal response to applications of nanotechnology. Structured interviews
with experts on nanotechnology from North West Europe were conducted using repertory grid methodology in conjunction with
generalized Procrustes analysis to examine the psychological constructs underlying societal uptake of 15 key applications
of nanotechnology drawn from different areas (e.g. medicine, agriculture and environment, chemical, food, military, sports,
and cosmetics). Based on expert judgement, the main factors influencing societal response to different applications of nanotechnology
will be the extent to which applications are perceived to be beneficial, useful, and necessary, and how 'real' and physically
close to the end-user these applications are perceived to be by the public. 相似文献
88.
An ascorbate oxidase (AsOx) (E.C.1.10.3.3) purified from Lagenaria siceraria fruit was immobilized covalently onto a carboxylated multiwalled carbon nanotubes and polyaniline (c-MWCNT/PANI) layer electrochemically deposited on the surface of an Au electrode. The diffusion coefficient of ascorbic acid was determined as 3.05 × 10(-4) cm(2) s(-1). The behavior of different electrolytes on electro-deposition was also studied. An ascorbate biosensor was fabricated using a AsOx/c-MWCNT/PANI/Au electrode as a working electrode, Ag/AgCl (3 M/saturated KCl) as standard and Pt wire as an auxiliary electrode connected through a potentiostat. Linear range, response time and detection limit were 2-206 μM, 2 s and 0.9 μM respectively. The biosensor showed optimum response at pH 5.8 and in a broader temperature range (30-45 °C), when polarized at +0.6 V. The biosensor was employed for determination of ascorbic acid level in sera, fruit juices and vitamin C tablets. The sensor was evaluated with 91% recovery of added ascorbic acid in sera and 6.5% and 11.4% within and between batch coefficients of variation respectively for five serum samples. There was a good correlation (r = 0.98) between fruit juice ascorbic acid values by the standard 2,6-dichlorophenolindophenol (DCPIP) method and the present method. The enzyme electrode was used 200 times over a period of two months, when stored at 4 °C. The biosensor has advantages over earlier enzyme sensors in that it has no leakage of enzyme, due to the covalent coupling of enzyme with the support, lower response time, wider working range, higher storage stability and no interference by serum substances. 相似文献
89.
Nanosized Pd17Se15 and PdP2 were synthesized at moderate temperature (using less toxic TOPO in case of PdP2) and explored for the first time to catalyze transfer hydrogenation (TH) of aldehydes / ketones using 2-propanol as a source of hydrogen. The optimum catalyst loading was equivalent to 1.0 mol % of Pd. The round shaped Pd17Se15 NPs (15 to 30 nm), resulted on reacting (3-(phenylseleno)propylamine) with Na2PdCl4 in a mixture (1 : 1) of olylamine and 1-octadecene at 250 °C for 50 min. Nanoflowers of PdP2 (25 to 55 nm) were obtained by reacting Na2PdCl4 with trioctylphosphine oxide (TOPO) in a similar solvent mixture at 350 °C for 60 min. Both the NPs were found air insensitive and authenticated with powder X-ray diffraction, HR-TEM, SEM, SEM-EDX and XPS. The conversion was found more efficient for aldehydes in comparison to that of ketones. In comparison to most of the other Pd based nano-phases, reported earlier, the present NPs are somewhat better activators for TH. 相似文献
90.
Feliu Elisenda Kaihnsa Nidhi de Wolff Timo Yürük Oğuzhan 《Journal of Dynamics and Differential Equations》2022,34(2):825-852
Journal of Dynamics and Differential Equations - Multistationarity in molecular systems underlies switch-like responses in cellular decision making. Determining whether and when a system displays... 相似文献