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241.
Poly(p‐phenylene) with Poly(ethylene glycol) Chains and Amino Groups as a Functional Platform for Controlled Drug Release and Radiotherapy 下载免费PDF全文
Bahar Guler Huseyin Akbulut Firat Baris Barlas Caner Geyik Dilek Odaci Demirkol Ahmet Murat Senisik Halil Armagan Arican Hakan Coskunol Suna Timur Yusuf Yagci 《Macromolecular bioscience》2016,16(5):730-737
Conventional cancer treatments such as chemotherapy, radiotherapy, or combination of these two result in side effects, which lower the quality of life of the patients. To overcome problems with these methods, altering the drug properties by conjugating them to carrier polymers has emerged. Such polymeric carriers also hold the potential to make tumor cells more sensitive to radiation therapy. Herein, poly(p‐phenylene) (PPP) polymer with poly(ethylene glycol) (PEG) chains and primary amino groups (PPP‐NH2‐g‐PEG) is synthesized and conjugated with anticancer drug Doxorubicin (DOX). pH dependent drug release experiments are performed at pH 5.3 and pH 7.4, respectively. Cell viability studies on human cervix adenocarcinoma cells show that lower doses of DOX inhibit cell proliferation when conjugated with nontoxic doses of PPP‐NH2‐g‐PEG polymer. Additionally, PPP‐NH2‐g‐PEG/Cys/DOX bioconjugate significantly increases radiosensitive properties of DOX. It is possible to use lower doses of DOX when conjugated to PPP‐NH2‐g‐PEG in combination with radiotherapy.
242.
Hanjun Sun Ibrahim Halil
ner Tao Wang Tao Zhang Oleksandr Selyshchev Christof Neumann Yubin Fu Zhongquan Liao Shunqi Xu Yang Hou Andrey Turchanin Dietrich R. T. Zahn Ehrenfried Zschech Inez M. Weidinger Jian Zhang Xinliang Feng 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(30):10476-10482
Conjugated polymers featuring tunable band gaps/positions and tailored active centers, are attractive photoelectrode materials for water splitting. However, their exploration falls far behind their inorganic counterparts. Herein, we demonstrate a molecular engineering strategy for the tailoring aromatic units of conjugated acetylenic polymers from benzene‐ to thiophene‐based. The polarized thiophene‐based monomers of conjugated acetylenic polymers can largely extend the light absorption and promote charge separation/transport. The C≡C bonds are activated for catalyzing water reduction. Using on‐surface Glaser polycondensation, as‐fabricated poly(2,5‐diethynylthieno[3,2‐b]thiophene) on commercial Cu foam exhibits a record H2‐evolution photocurrent density of 370 μA cm?2 at 0.3 V vs. reversible hydrogen electrode among current cocatalyst‐free organic photocathodes (1–100 μA cm?2). This approach to modulate the optical, charge transfer, and catalytic properties of conjugated polymers paves a critical way toward high‐activity organic photoelectrodes. 相似文献
243.
Bahar Bilgin Sokmen Serpil Ugras Hasan Yucel Sarikaya Halil Ibrahim Ugras Refiye Yanardag 《Applied biochemistry and biotechnology》2013,171(8):2030-2039
Some series of arylidene barbiturates and thiobarbiturates were evaluated for their antibacterial, antioxidant, and urease inhibition activities. The arylidene barbiturates and thiobarbiturates were tested for antimicrobial activity using the agar well diffusion technique against 13 bacteria. The synthesized compounds (1a–g) were screened for antiurease and antioxidant activities. The results showed that the synthesized compounds (1a–g) had effective antiurease, antioxidant, and antibacterial activities. 相似文献
244.
Akbas Elif Soyler U. Betul Oztop Mecit Halil 《Applied biochemistry and biotechnology》2019,188(1):54-71
Applied Biochemistry and Biotechnology - Oleoresin capsicum (OC) is an extract of chili pepper containing the active agent capsaicin. In this study, OC-loaded nanoemulsions were prepared by... 相似文献
245.
Veldman D Ipek O Meskers SC Sweelssen J Koetse MM Veenstra SC Kroon JM van Bavel SS Loos J Janssen RA 《Journal of the American Chemical Society》2008,130(24):7721-7735
The electro-optical properties of thin films of electron donor-acceptor blends of a fluorene copolymer (PF10TBT) and a fullerene derivative (PCBM) were studied. Transmission electron microscopy shows that in these films nanocrystalline PCBM clusters are formed at high PCBM content. For all concentrations, a charge transfer (CT) transition is observed with absorption spectroscopy, photoluminescence, and electroluminescence. The CT emission is used as a probe to investigate the dissociation of CT excited states at the donor-acceptor interface in photovoltaic devices, as a function of an applied external electric field and PCBM concentration. We find that the maximum of the CT emission shifts to lower energy and decreases in intensity with higher PCBM content. We explain the red shift of the emission and the lowering of the open-circuit voltage (V(OC)) of photovoltaic devices prepared from these blends with the higher relative permittivity of PCBM (epsilon(r) = 4.0) compared to that of the polymer (epsilon(r) = 3.4), stabilizing the energy (E(CT)) of CT states and of the free charge carriers in blends with higher PCBM concentration. We show that the CT state has a short decay time (tau = ca. 4 ns) that is reduced by the application of an external electric field or with increasing PCBM content. The field-induced quenching can be explained quantitatively with the Onsager-Braun model for the dissociation of the CT states when including a high electron mobility in nanocrystalline PCBM clusters. Furthermore, photoinduced absorption spectroscopy shows that increasing the PCBM concentration reduces the yield of neutral triplet excitons forming via electron-hole recombination, and increases the lifetime of radical cations. The presence of nanocrystalline domains with high local carrier mobility of at least one of the two components in an organic heterojunction may explain efficient dissociation of CT states into free charge carriers. 相似文献
246.
247.
Bayrakçeken F Aktaş S Unlügedik A Karaaslan I 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2003,59(7):1663-1666
Electronic absorption spectra in the 210-250 nm region, were reported for the allyl radical in the vapor phase and subsequent reactions have been investigated by kinetic spectroscopy and gas-liquid chromatography. Extinction coefficients are calculated for the strong absorption bands of the allyl free radical by measured rate constants at room temperature. 相似文献
248.
Yucelen GI Choudhury RP Vyalikh A Scheler U Beckham HW Nair S 《Journal of the American Chemical Society》2011,133(14):5397-5412
We report the identification and elucidation of the mechanistic role of molecular precursors and nanoscale (1-3 nm) intermediates with intrinsic curvature in the formation of single-walled aluminosilicate nanotubes. We characterize the structural and compositional evolution of molecular and nanoscale species over a length scale of 0.1-100 nm by electrospray ionization mass spectrometry, nuclear magnetic resonance spectroscopy ((27)Al liquid-state, (27)Al and (29)Si solid-state MAS), and dynamic light scattering. Together with structural optimization of key experimentally identified species by solvated density functional theory calculations, this study reveals the existence of intermediates with bonding environments, as well as intrinsic curvature, similar to the structure of the final nanotube product. We show that "proto-nanotube-like" intermediates with inherent curvature form in aqueous synthesis solutions immediately after initial hydrolysis of reactants, disappear from the solution upon heating to 95 °C due to condensation accompanied by an abrupt pH decrease, and finally form ordered single-walled aluminosilicate nanotubes. Detailed quantitative analysis of NMR and ESI-MS spectra from the relevant aluminosilicate, aluminate, and silicate solutions reveals the presence of a variety of monomeric and polymeric aluminate and aluminosilicate species (Al(1)Si(x)-Al(13)Si(x)), such as Keggin ions [AlO(4)Al(12)(OH)(24)(H(2)O)(12)](7+) and polynuclear species with a six-membered Al oxide ring unit. Our study also directly reveals the complexation of aluminate and aluminosilicate species with perchlorate species that most likely inhibit the formation of larger condensates or nontubular structures. Integration of all of our results leads to the construction of the first molecular-level mechanism of single-walled metal oxide nanotube formation, incorporating the role of monomeric and polymeric aluminosilicate species as well as larger nanoparticles. 相似文献
249.
Halil İbrahim Ulusoy Ramazan Gürkan Öznur Yılmaz Mehmet Akçay 《Journal of Analytical Chemistry》2012,67(2):131-139
A sensitive and selective method has been developed for the determination of chromium in water samples based on using cloud
point extraction (CPE) preconcentration and determination by flame atomic absorption spectrometry (FAAS). The method is based on the complexation of Cr(III) ions with Brilliant Cresyl Blue (BCB) in the presence of non-ionic surfactant Triton X-114. Under the optimum conditions, the preconcentration of 50 mL of water
sample in the presence of 0.5 g/L Triton X-114 and 1.2 × 10−5 M BCB permitted the detection of 0.42 μg/L chromium(III). The calibration graph was linear in the range of 1.5–70 μg/L, and
the recovery of more than 99% was achieved. The proposed method was used in FAAS determination of Cr(III) in water samples
and certified water samples. In addition, the developed CPE-FAAS method was also used for speciation of the inorganic chromium
species after reduction of Cr(VI) to Cr(III) using a thiosulphate solution of 120 mg/L in the presence of Hg(II) ion as a
stabilizer. 相似文献
250.
Daoud S. Daoud Ipek Caltinoglu 《Journal of Mathematical Analysis and Applications》2007,333(2):1153-1164
We are interested in solving time dependent problems using domain decomposition methods. In the classical approach, one discretizes first the time dimension and then one solves a sequence of steady problems by a domain decomposition method. In this article, we treat directly the time dependent problem and we study a Schwarz waveform relaxation algorithm for the convection diffusion equation. We study the convergence of the overlapping Schwarz waveform relaxation method for solving the reaction-diffusion equation over multi-overlapped subdomains. Also we will show that the method converges linearly and superlinearly over long and short time intervals, and the convergence depends on the size of overlap. Numerical results are presented from solutions of a specific model problems to demonstrate the convergence, linear and superlinear, and the role of the overlap size. 相似文献