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Cationic and amphipathic cell-penetrating peptides (CPPs): Their structures and in vivo studies in drug delivery
Jennica L. Zaro,Wei-Chiang Shen
Front. Chem. Sci. Eng.. 2015, 9 (4 ): 407-427.
https://doi.org/10.1007/s11705-015-1538-y
Over the past few decades, cell penetrating peptides (CPPs) have become an important class of drug carriers for small molecules, proteins, genes and nanoparticle systems. CPPs represent a very diverse set of short peptide sequences (10?30 amino acids), generally classified as cationic or amphipathic, with various mechanisms in cellular internalization. In this review, a more comprehensive assessment of the chemical structural characteristics, including net cationic charge, hydrophobicity and helicity was assembled for a large set of commonly used CPPs, and compared to results from numerous in vivo drug delivery studies. This detailed information can aid in the design and selection of effective CPPs for use as transport carriers in the delivery of different types of drug for therapeutic applications.
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SERS nanoprobes for bio-application
Han-Wen Cheng,Jin Luo,Chuan-Jian Zhong
Front. Chem. Sci. Eng.. 2015, 9 (4 ): 428-441.
https://doi.org/10.1007/s11705-015-1536-0
The ability to tune the size, shape, composition and surface properties impart nanoparticles with the desired functions for bio-application. This article highlights some of the recent examples in the exploration of metal (e.g., gold and silver) nanoparticles, especially those with magnetic properties and bio-conjugated structures, as theranostic nanoprobes. Such nanoprobes exhibit tunable optical, spectroscopic, magnetic, and electrical properties for signal amplifications. Examples discussed in this article will focus on the nanoproble-enhanced colorimetric detection and surface enhanced Raman scattering (SERS) detection of biomarkers or biomolecules such as proteins and DNAs. The understanding of factors controlling the biomolecular interactions is essential for the design of SERS nanoprobes with theranostic functions.
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Alkaline modification of ZSM-5 catalysts for methanol aromatization: The effect of the alkaline concentration
Zhenhao Wei,Tengfei Xia,Minghui Liu,Qingsheng Cao,Yarong Xu,Kake Zhu,Xuedong Zhu
Front. Chem. Sci. Eng.. 2015, 9 (4 ): 450-460.
https://doi.org/10.1007/s11705-015-1542-2
The effects of alkaline treatment on the physical properties of ZSM-5 catalysts and on their activities for methanol to aromatics conversion have been investigated. A mild alkaline treatment (0.2 and 0.3 mol/L NaOH) created mesopores in the parent zeolite with no obvious effect on acidity. The presence of mesopores gives the catalyst a longer lifetime and higher selectivity for aromatics. Treatment with 0.4 mol/L NaOH decreased the number of Brønsted acid sites due to dealumination and desilication, which resulted in a lower deactivation rate. In addition, more mesopores were produced than with the mild alkaline treatment. As a result, the lifetime of the sample treated with 0.4 mol/L NaOH was almost five times that of the parent ZSM-5. Treatment with a higher alkaline concentration (0.5 mol/L) greatly reduced the number of Brønsted acid sites and the number of micropores resulting in incomplete methanol conversion. When the alkaline-treated catalysts were washed with acid, some of the porosity was restored and a slight increase in selectivity for aromatics was obtained.
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Selective conversion of cellulose to hexitols over bi-functional Ru-supported sulfated zirconia and silica-zirconia catalysts
Zhiqiang Song,Hua Wang,Yufei Niu,Xiao Liu,Jinyu Han
Front. Chem. Sci. Eng.. 2015, 9 (4 ): 461-466.
https://doi.org/10.1007/s11705-015-1543-1
We report a process of selective conversion of microcrystalline cellulose to hexitols over bi-functional Ru-supported sulfated zirconia and silica-zirconia catalysts. A 58.1% yield of hexitols and a 71.0% conversion of cellulose were achieved over Ru/SZSi(100:15)-773 catalyst at 443 K. The as-synthesized catalysts were characterized by X-ray diffraction (XRD), BET, thermogravimetric analysis and pyridine adsorption Fourier transform infrared spectroscopy (FTIR). XRD results indicated that the sulfated catalysts were pure tetragonal phase of ZrO2 when calcined at 773 K. Monoclinic zirconia appeared at the calcination temperature of 873 K, and the content of monoclinic phase increased with the elevating temperature. Compared with sulfated zirconia catalyst, sulfated silica-zirconia catalysts possessed a higher ratio of Brønsted to Lewis on the surface of catalysts, as shown from pyridine adsorption FTIR results. The reaction results indicated that the tetragonal zirconia, which is necessary for the formation of superacidity, was the active phase to cellulose conversion. The higher amounts of Brønsted acid sites can remarkably accelerate the cellulose depolymerization and promote side reactions that convert C5–C6 alcohols into the unknown soluble degradation products.
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Organogelators based on p -alkoxylbenzamide and their self-assembling properties
Yan Zhai,Wei Chai,Wenwen Cao,Zipei Sun,Yaodong Huang
Front. Chem. Sci. Eng.. 2015, 9 (4 ): 488-493.
https://doi.org/10.1007/s11705-015-1503-9
A series of p -alkoxylbenzamides featuring a long alkyl chain have been synthesized and are readily to form stable gels in a variety of organic solvents. Their self-assembly properties and structure-property relationship were investigated by scanning electron microscopy, X-ray diffraction, 1 H nuclear magnetic resonance, and Fourier transform infrared spectroscopy. The gels formed were multi-responsive to environmental stimuli such as temperature and fluoride anion. The results show that a combination of hydrogen bonding, π-π stacking and van der Waals interaction result in the aggregation of p -alkoxylbenzamides to form three-dimension networks, depending on the length of the long alkyl chain.
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DsbA-DsbAmut fusion chaperon improved soluble expression of human trypsinogen-1 in Escherichia coli
Ye Liu,Wenyong Zhang,Xubin Yang,Guangbo Kang,Damei Wang,He Huang
Front. Chem. Sci. Eng.. 2015, 9 (4 ): 511-521.
https://doi.org/10.1007/s11705-015-1519-1
A co-expressing system of DsbA-DsbAmut was suggested for the first time to enhance the soluble expression of human trypsin-1. As a control, leaderless DsbA chaperone was also co-expressed with human trypsin-1. Vectors pET39b-trypsin and pET28a-DsbA-DsbAmut -trypsin with the above two DsbA fusion tag were constructed. The strain with vector pET39b-trypsin expressed fusion protein DsbA-trypsin in form of inclusion bodies. While in E. coli BL21 (DE3) strain with vector pET28a-DsbA-DsbAmut -trypsin, the soluble expression of trypsin fusion protein was achieved. Under the optimized expression conditions, the soluble fraction accounted for about 49.43% of total DsbA-DsbAmut -trypsin proteins in crude supernatant. The purification yield was 4.15% by nickel chelating chromatography and 3.3 mg activated trypsin with a purity of 88.68% was obtained from 1 L LB broth. To detect the possible functions of DsbA series chaperons in trypsin fusion protein, we analyzed the primary three-dimensional structure of fusion proteins, mainly focusing on the compatibleness between trypsin and fusion chaperons. The results suggested that (1) besides the primary function in periplasm, leaderless DsbA or DsbAmut may also act as a signal sequences-like leader targeted to periplasm that partly relieved the pressure from fusion protein overexpression and inclusion body formation, and (2) as there was significant soluble expression of DsbA-DsbAmut -trypsin compared with DsbA-trypsin, DsbAmut may function as charge or hydrophobic balance in recombinant protein DsbA-DsbAmut -trypsin.
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Effects of operational and structural parameters on cell voltage of industrial magnesium electrolysis cells
Ze Sun,Chenglin Liu,Guimin Lu,Xingfu Song,Jianguo Yu
Front. Chem. Sci. Eng.. 2015, 9 (4 ): 522-531.
https://doi.org/10.1007/s11705-015-1539-x
Electric field is the energy foundation of the electrolysis process and the source of the multiphysical fields in a magnesium electrolysis cell. In this study, a three-dimensional numerical model was developed and used to calculate electric field at the steady state through the finite element analysis. Based on the simulation of the electric field, the operational and structural parameters, such as the current intensity, anode thickness, cathode thickness, and anode-cathode distance (ACD), were investigated to obtain the minimum cell voltage. The optimization is to obtain the minimum resistance voltage which has a significant effect on the energy consumption in the magnesium electrolysis process. The results indicate that the effect of the current intensity on the voltage could be ignored and the effect of the ACD is obvious. Moreover, there is a linear decrease between the voltage and the thicknesses of the anode and cathode; and the anode-cathode working height also has a significant effect on the voltage.
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