共查询到10条相似文献,搜索用时 156 毫秒
1.
《Current Applied Physics》2008,8(6):646-650
The polymerization of trimethylene carbonate (TMC) in the presence of HCl · Et2O via activated monomer mechanism was performed to synthesize linear and star-shaped block copolymers composed of polyethyleneglycol (PEG) and poly(trimethylene carbonate) (PTMC). The obtained PTMCs had molecular weights close to the theoretical values calculated from the TMC to PEG molar ratios and exibited monomodal GPC curves. We successfully prepared PEG and PTMC linear and star-shaped block copolymers by activated monomer mechanism. The characterization for formation of micelle of block copolymers in an aqueous phase was carried out by using NMR, dynamic light scattering (DLS), AFM and fluorescence techniques (FL). The block copolymers gave micelles with a critical micelle concentration (CMC) ranging 1.88 × 10−2–3.09 × 10−3 mg/mL depended on the molecular shape of block copolymers. The diameters of micelles, measured by DLS, were 100–250 nm. Most micelles exhibited a spherical shape in AFM. 相似文献
2.
Using the absorption probes 1-H-imidazol-1-yloxy-4,5-dihydro-4,4,5,5-tetramethyl-2-ethyl-3-oxide, 1-H-imidazol-1-yloxy-4,5-dihydro-4,4,5,5-tetramethyl-2-nitrophenyl-3-oxide,
and 1-H-imidazol-1-yloxy-4,5-dihydro-4,4,5,5-tetramethyl-2-undecyl-3-oxide, the micropolarity of micellar aggregates formed
in aqueous solutions of poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) triblock copolymers, Pluronics L62,
L64, and F127, as well as in reverse micellar systems of F127/butanol/water, has been investigated These absorption probes
have different hydrophilic/hydrophobic features and solvatochromic properties. Their specific absorption parameters, sensitive
to changes in micropolarity, were calibrated using the reference curves carried out in homogeneous tetraethyleneglycol/water
mixtures. The probes were able to detect changes in the micelle micropolarity induced by hydration. Thus, with the help of
calibration solutions, the effective local hydration of the polymeric chain sensed by the molecular probe solubilized in the
guest aggregate was quantified and hypothetical relative locations of the probes in micelles have been proposed. The probes
evidence differences in the micropolarity function of the structure (nature) and concentration of the Pluronic block copolymers. 相似文献
3.
E. K. Efthimiadou C. Tapeinos P. Bilalis G. Kordas 《Journal of nanoparticle research》2011,13(12):6725-6736
Amphiphilic block copolymers are well established as building blocks for the preparation of micellar drug carriers. The functional
polymer micelles possess several advantages, such as high drug efficiency, targeted delivery, and minimized cytotoxicity.
The synthesis of block copolymers using nano-structured templates has emerged as a useful and versatile approach for preparing
drug carriers. Here, we report the synthesis of a smart polymeric compound of a diblock PLA-Lys-b-PEG copolymer containing doxorubicin. We have synthesized functionalized diblock copolymers, with lysinol, poly(lactide)
and monomethoxy poly(ethylene glycol) via thermal ring-opening polymerization and a subsequent six-step substitution reaction.
A variety of spectroscopic methods were employed here to verify the product of our synthesis. 1H-Nuclear magnetic resonance and Fourier transform infrared studies validated the expected synthesis of copolymers. Doxorubicin
is chemically loaded into micelles, and the ex vitro release can be evaluated either in weak acidic or in SBF solution by
UV–vis spectroscopy. Dynamic light scattering, thermo gravimetric analysis, and size exclusion chromatography have also been
used. 相似文献
4.
Siyuan Han Huan Wang Xingjie Liang Liming Hu Min Li Yan Wu 《Journal of nanoparticle research》2011,13(9):4371-4385
A novel poly(l-aspartic) derivative (PAL-DPPE) containing polylactide and 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) segments
has been successfully synthesized. The chemical structures of the copolymers were confirmed by Fourier-transform infrared
spectroscopy (FTIR), NMR (1H NMR, 13C NMR, 31P NMR), and thermogravimetric analysis (TGA). Fluorescence spectroscopy, dynamic light scattering (DLS), and transmission
electron microscopy (TEM) confirmed the formation of micelles of the PAL-DPPE copolymers. In order to estimate the feasibility
as novel drug carriers, an anti-tumor model drug doxorubicin (DOX) was incorporated into polymeric micelles by double emulsion
and nanoprecipitation method. The DOX-loaded micelle size, size distribution, and encapsulation efficiency (EE) were influenced
by the feed weight ratio of the copolymer to DOX. In addition, in vitro release experiments of the DOX-loaded PAL-DPPE micelles
exhibited that faster release in pH 5.0 than their release in pH 7.4 buffer. The poly(l-aspartic) derivative copolymer was proved to be an available carrier for the preparation of micelles for anti-tumor drug
delivery. 相似文献
5.
Berret JF Cristobal G Hervé P Oberdisse J Grillo I 《The European physical journal. E, Soft matter》2002,9(4):301-311
We report on the phase behavior and scattering properties of colloidal complexes made from block copolymers and surfactants. The copolymer is poly(sodium acrylate)-b-poly(acrylamide), hereafter abbreviated as PANa-PAM, with molecular weight 5000 g/mol for the first block and 30000 g/mol for the second. In aqueous solutions and neutral pH, poly(sodium acrylate) is a weak polyelectrolyte, whereas poly(acrylamide) is neutral and in good-solvent conditions. The surfactant is dodecyltrimethylammonium bromide (DTAB) and is of opposite charge with respect to the polyelectrolyte block. Combining dynamical light scattering and small-angle neutron scattering, we show that in aqueous solutions PANa-PAM diblocks and DTAB associate into colloidal complexes. For surfactant-to-polymer charge ratios Z lower than a threshold (Z(C) approximately 0.3), the complexes are single surfactant micelles decorated by few copolymers. Above the threshold, the colloidal complexes reveal an original core-shell microstructure. We have found that the core of typical radius 100-200 A is constituted from densely packed surfactant micelles connected by the polyelectrolyte blocks. The outer part of the colloidal complex is a corona and is made from the neutral poly(acrylamide) chains. Typical hydrodynamic sizes for the whole aggregate are around 1000 A. The aggregation numbers expressed in terms of numbers of micelles and copolymers per complex are determined and found to be comprised between 100-400, depending on the charge ratio Z and on the total concentration. We have also shown that the sizes of the complexes depend on the exact procedure of the sample preparation. We propose that the driving mechanism for the complex formation is similar to that involved in the phase separation of homopolyelectrolyte/surfactant systems. With copolymers, the presence of the neutral blocks prevents the macroscopic phase separation from occurring. 相似文献
6.
Polymeric Micelles Employing Platinum(II) Linker for the Delivery of the Kinase Inhibitor Dactolisib
Haili Shi Bo Lou Mies J. van Steenbergen Niels J. Sijbrandi Wim E. Hennink Robbert J. Kok 《Particle & Particle Systems Characterization》2019,36(8)
Polymeric micelles are attractive nanocarriers for hydrophobic drug molecules such as the kinase inhibitor dactolisib. Two different poly(ethylene glycol)–poly(acrylic acid) (PEG‐b‐PAA) block‐copolymers are synthesized, PEG(5400)‐b‐PAA(2000) and PEG(10000)‐b‐PAA(3700), respectively. Polymeric micelles are formed by self‐assembly once dactolisib is conjugated via the ethylenediamine platinum(II) linker (Lx) to the PAA block of the block copolymers. Dactolisib micelles with dactolisib loading content of 17% w/w show good colloidal stability and display sustained release of Lx‐dactolisib over 96 h in PBS at 37 °C, while media containing reagents that compete for platinum coordination (e.g., glutathione (GSH) or dithiothreitol (DTT)) effectuate release of the parent inhibitor dactolisib at similar release rates. Dactolisib/lissamine‐loaded micelles are internalized by human breast adenocarcinoma cells (MCF‐7) in a dose and time‐dependent manner as demonstrated by confocal microscopy. Dactolisib‐loaded micelles inhibit the PI3K/mTOR signaling pathway at low concentrations (400 × 10?9 m ) and exhibit potent cytotoxicity against MCF‐7 cells with IC50 values of 462 ± 46 and 755 ± 75 × 10?9 m for micelles with either short or longer PEG‐b‐PAA block lengths. In conclusion, dactolisib loaded PEG‐b‐PAA micelles are successfully prepared and hold potential for nanomedicine‐based tumor delivery of dactolisib. 相似文献
7.
Emanuela Fabiola Craparo Girolamo Teresi Maria Chiara Ognibene Maria Pia Casaletto Maria Luisa Bondì Gennara Cavallaro 《Journal of nanoparticle research》2010,12(7):2629-2644
In this article, the synthesis of two amphiphilic polyaspartamide copolymers, useful to obtain polymeric nanoparticles without
using surfactants or stabilizing agents, is described. These copolymers were obtained starting from α,β-poly-(N-2-hydroxyethyl)-dl-aspartamide (PHEA) by following a novel synthetic strategy. In particular, PHEA and its pegylated derivative (PHEA-PEG2000) were functionalized with poly(lactic acid) (PLA) through 1,1′-carbonyldiimidazole (CDI) activation to obtain PHEA–PLA and
PHEA-PEG2000–PLA graft copolymers, respectively. These copolymers were properly purified and characterized by 1H-NMR, FT-IR, and Size Exclusion Chromatography (SEC) analyses, which confirmed that derivatization reactions occurred. Nanoparticles
were obtained from PHEA–PLA and PHEA-PEG2000–PLA graft copolymers by using the high pressure homogenization-solvent evaporation method, avoiding the use of surfactants
or stabilizing agents. Polymeric nanoparticles were characterized by dimensional analysis, before and after freeze-drying
process, and Scanning Electron Microscopy (SEM). Zeta potential measurements and X-ray Photoelectron Spectroscopy (XPS) analysis
demonstrated the presence of PEG and/or PHEA onto the PHEA-PEG2000–PLA and PHEA–PLA nanoparticle surface, respectively. 相似文献
8.
Cold crystallization of poly (l-lactide)/poly (d-lactide) blends at low temperatures results in the formation of a stereocomplex with loose intermolecular packing. Upon heating, it undergoes significant reorganization into a compact one with an extremely high melting point via a solid–solid transition. In contrast, the stereocomplex crystallized at high temperatures exhibits little reorganization and thus a relatively low melting point. 相似文献
9.
Williams AA Fakayode SO Alptürk O Jones CM Lowry M Strongin RM Warner IM 《Journal of fluorescence》2008,18(2):285-296
Novel fluorescent chiral molecular micelles (FCMMs) were synthesized, characterized, and employed as chiral selectors for
enantiomeric recognition of non-fluorescent chiral molecules using steady state fluorescence spectroscopy. The sensitivity
of the fluorescence technique allowed for investigation of low concentrations of chiral selector (3.0 × 10−5 M) and analyte (5.0 × 10−6 M) to be used in these studies. The chiral interactions of glucose, tartaric acid, and serine in the presence of FCMMs poly(sodium
N-undecanoyl-l-tryptophanate) [poly-l-SUW], poly(sodium N-undecanoyl-l-tyrosinate) [poly-l-SUY], and poly(sodium N-undecanoyl-l-phenylalininate) [poly-SUF] were based on diastereomeric complex formation. Poly-l-SUW had a significant fluorescence emission spectral difference as compared to poly-l-SUY and poly-l-SUF for the enantiomeric recognition of glucose, tartaric acid, and serine. Studies with the hydrophobic molecule α-pinene
suggested that poly-l-SUY and poly-l-SUF had better chiral discrimination ability for hydrophobic analytes as compared to hydrophilic analytes. Partial-least-squares
regression modeling (PLS-1) was used to correlate changes in the fluorescence emission spectra of poly-l-SUW due to varying enantiomeric compositions of glucose, tartaric acid, and serine for a set of calibration samples. Validation
of the calibration regression models was determined by use of a set of independently prepared samples of the same concentration
of chiral selector and analyte with varying enantiomeric composition. Prediction ability was evaluated by use of the root-mean-square
percent relative error (RMS%RE) and was found to range from 2.04 to 4.06%.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
10.
ChangYang Gong YuJun Wang XiuHong Wang XiaWei Wei QinJie Wu BiLan Wang PengWei Dong LiJuan Chen Feng Luo ZhiYong Qian 《Journal of nanoparticle research》2011,13(2):721-731
Polymeric micelles, prepared by self-assembly of biodegradable poly(ethylene glycol)-poly(ε-caprolactone)-poly(ethylene glycol)
(PEG–PCL–PEG, PECE) copolymer in aqueous solution, were proved to be a potential carrier for hydrophobic drug honokiol in
our previous contribution. In this study, the safety of blank PECE micelles was evaluated in vitro and in vivo before its
further application in biomedical field. The average particle size of obtained micelle was 83.47 ± 0.44 nm, and polydisperse
index was 0.27 ± 0.01. Also, the zeta potential of prepared micelles was about −0.41 ± 0.02 mV. Otherwise, cytotoxicity of
PECE micelles was evaluated by cell viability assay using L929 cells, and in vitro hemolytic test was also performed. In vivo
acute toxicity evaluation and histopathological study of PECE micelles were conducted in BALB/c mice by intravenous administration.
Furthermore, serum chemistry profile and complete blood count test were performed. In acute toxicity test, the mice were observed
continuously for 7 days. For histopathological study, samples including heart, liver, spleen, lung, and kidneys were histochemical
prepared and stained with hematoxylin-eosin (H&E). No mortality or significant signs of acute toxicity was observed during
the whole observation period, and there is no significant lesion to be shown in histopathological study of major organs. The
maximal tolerance dose of PECE micelles (100 mg/mL) by intravenous administration was calculated to be higher than 10 g/kg
body weight (b.w.). The results indicated that the obtained PECE micelles was non-toxic after intravenous administration,
and could be a safe candidate for hydrophobic drug delivery system. 相似文献