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Preparation and in vitro cytotoxicity study of poly(aspartic acid) stabilized magnetic nanoparticles
Peng YANG, Wei CHEN, Changchun WANG
Front Chem Chin. 2011, 6 (1): 9-14.
https://doi.org/10.1007/s11458-011-0222-0
Biocompatible magnetic nanoparticles were prepared by co-precipitation method in the presence of poly(aspartic acid) (PAsp) as stabilizer, which was one of the most extensively studied and used poly(amino acids). As a biocompatible dispersant, PAsp was successfully attached to the Fe3O4 nanoparticles, which was approved by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). From X-ray diffraction (XRD) and vibrating sample magnetometry (VSM) measurement results, it was found that PAsp stabilized iron oxide nanoparticles possess excellent Fe3O4 crystal structure and superparamagnetic property. Compared with trisodium citrate stabilized magnetic nanoparticles, PAsp stabilized magnetic nanoparticles were biocompatible and with lower cytotoxicity, which makes it more applicable in medicine, biology and biomaterial science.
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Selective detection of phosphaphenanthrene-containing luminophors with aggregation-induced emission enhancement to transition metal ions
Lijun QIAN, Bin TONG, Shu SUN, Jianbing SHI, Junge ZHI, Yuping DONG
Front Chem Chin. 2011, 6 (1): 15-20.
https://doi.org/10.1007/s11458-011-0221-1
Transition metal ions (Pb2+, Zn2+, Cd2+, Co2+, Mn2+, Cu2+, Ni2+, Hg2+, Ag+, Fe3+) in water are used to quench emission of 2-(6-oxido-6H-dibenz<c,e><1,2>oxaphosphorin-6-yl)-1,4-phenylene-bis(p-pentyloxylbenzoate)s (MD5) with aggregation-induced emission enhancement (AIEE) in water-acetonitrile (AN) mixture (80:20 by volume). Among all metal ions, Fe3+ exhibits the highest quenching efficiency on AIEE of MD5 even when the concentration of Fe3+ is lower than 1×10-6 mol/L. The quenching efficiency of Hg2+ is lower than that of Fe3+ at the same concentration, though MD5 is used to detect Hg2+ efficiently, too. To other metal ions, low quenching efficiency has few relations with a wider concentration range. The UV absorbance spectra show only red shift of absorbance wavelength in the presence of Hg2+ and Fe3+, which indicates a salt-induced J-aggregation. SEM photos reveal larger aggregation and morphological change of nanoparticles of MD5 in water containing Hg2+ and Fe3+, which reduce the surface area of MD5 emission for further aggregation. The selective quenching effect of transition metal ions to emission of MD5 has a potential application in chemical sensors of some metal ions.
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Synthesis of cyclic carbonates and dimethyl carbonate using CO2 as a building block catalyzed by MOF-5/KI and MOF-5/KI/K2CO3
Jinliang SONG, Binbin ZHANG, Tao JIANG, Guanying YANG, Buxing HAN
Front Chem Chin. 2011, 6 (1): 21-30.
https://doi.org/10.1007/s11458-011-0225-x
The synthesis of cyclic carbonates or dimethyl carbonate (DMC) using CO2 as a building block is a very interesting topic. In this work, we found that the metal-organic framework-5 (MOF-5)/KI was an active and a selective catalytic system for the synthesis of cyclic carbonates from CO2 and epoxides, and MOF-5/KI/K2CO3 was efficient for the preparation of DMC from CO2, propylene, and methanol by a sequential route. The impacts of temperature, pressure, and reaction time length on the reactions were investigated, and the mechanism of the reactions is proposed on the basis of the experimental results.
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The effect of carboxymethyl-chitosan nanoparticles on proliferation of keloid fibroblast
Chao FENG, Xiguang CHEN, Jing ZHANG, Gangzheng SUN, Xiaojie CHENG, Zhiguo WANG, Hyun-Jin PARK
Front Chem Chin. 2011, 6 (1): 31-37.
https://doi.org/10.1007/s11458-011-0229-6
In this study, different molecular weight (MW) carboxymethyl chitosans (CM-chitosan) nanoparticles were prepared by ionic gelification. The particle size of nanoparticles was around 180–250 nm by dynamic light scattering (DLS) and transmission electron microscope (TEM). With the increase of CM-chitosan nanoparticles concentration from 2 to 200 μg/mL, the growth inhibition effects on the keloid fibroblast increased. At the concentration of 100 μg/mL, CM-chitosan nanoparticles with MW 6.3 kDa had a significant inhibitory effect (inhibition ratio 48.79%) of the proliferation of keloid fibroblast. Compared with CM-chitosan solution, the inhibition of CM-chitosan nanoparticles were lower in prior period and similar in later period. By analyzing the different effects of chitosan, CM-chitosan solution and CM-chitosan nanoparticles on proliferation of keloid fibroblast, we have found that the carboxylmethyl groups of CM-chitosan play an important role in inhibition of proliferation of keloid fibroblast.
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Aligned polymer fibers produced via an additive electric field
Yufei AI, Hongpeng ZHEN, Jun NIE, Dongzhi YANG
Front Chem Chin. 2011, 6 (1): 44-47.
https://doi.org/10.1007/s11458-011-0226-9
Electrospinning is known to be a highly versatile method to produce nanofibers, and several techniques have been developed to align nanofibers. In this paper, poly(vinyl alcohol) (PVA), poly(vinylpyrrolidone) (PVP), poly(propylene carbonate) (PC), poly(ethylene oxide) (PEO), PVA/Chitosan and PVA/Fe3O4 uniaxially aligned ultrafine fibers were obtained with electrospinning method by adding another electric field in the collection area. Alignment of the nanofibers was characterized by the use of digital cameras and field emission scanning electron microscopy, polarized Fourier transform infrared spectroscopy (FTIR), and wide-angle X-ray diffraction (XRD). The mechanism of fiber alignment was investigated as well.
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Preparation of chitosan/alginate microcapsules by high-voltage electrostatic method
Yufei AI, Shuang GUO, Qi ZHANG, Jing QIAO, Xuanyue GAO, Jun NIE, Dongzhi YANG
Front Chem Chin. 2011, 6 (1): 48-53.
https://doi.org/10.1007/s11458-011-0230-0
Chitosan and sodium alginate have the opposite charges; they can become a gelatin by the electrostatic attraction, High-voltage electrostatic droplet generator method was used to prepare chitosan-sodium alginate microcapsule. Multi-layer chitosan-sodium alginate microcapsule was prepared through layer-by-layer self-assembly, and the morphology was investigated. In addition, the release property of ofloxacin in microcapsules was studied by UV-Vis microscopy under different conditions such as pH value, layer number, etc. The results showed that the prepared microcapsules have a smooth surface with average particle size about 100 μm. The result of controlled release indicated that the prepared microcapsules are pH-independent, and the rate of release decreased when the layer number increases.
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