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Thermo-/pH-dual responsive properties of hyperbranched polyethylenimine grafted by phenylalanine
Chen, Jie,Xia, Jialiang,Tian, Huayu,Tang, Zhaohui,He, Chaoliang,Chen, Xuesi 대한약학회 2014 Archives of Pharmacal Research Vol.37 No.1
Novel thermo- and pH-dual responsive amphiphilic copolymers were synthesized based on hyperbranched polyethylenimine (PEI) by grafting $\small{L}$-phenylalanine. The phenylalanine-modified PEI exhibited lower cytotoxicity than commercial PEI. These copolymers showed the phenomena of phase transitions in response to pH and temperature. The dilute copolymer solution at lower pH displayed the higher LCST. Furthermore, LCST increased with the increasing of phenylalanine grafting density. LCST of these copolymers were tunable from 7.2 to $59.6^{\circ}C$ by the degree of amidation and pH of solution. DLS and TEM experiments certified that the copolymer chains aggregated to form small size particles as increasing the temperature above LCST. For these reasons, the obtained smart copolymers were considered to be potential gene/drug carriers in biomedical field.
Thermo-/pH-dual responsive properties of hyperbranched polyethylenimine grafted by phenylalanine
Jie Chen,Jialiang Xia,Huayu Tian,Zhaohui Tang,Chaoliang He,Xuesi Chen 대한약학회 2014 Archives of Pharmacal Research Vol.37 No.1
Novel thermo- and pH-dual responsiveamphiphilic copolymers were synthesized based on hyperbranchedpolyethylenimine (PEI) by grafting L-phenylalanine. The phenylalanine-modified PEI exhibited lowercytotoxicity than commercial PEI. These copolymersshowed the phenomena of phase transitions in response topH and temperature. The dilute copolymer solution atlower pH displayed the higher LCST. Furthermore, LCSTincreased with the increasing of phenylalanine graftingdensity. LCST of these copolymers were tunable from 7.2to 59.6 C by the degree of amidation and pH of solution. DLS and TEM experiments certified that the copolymerchains aggregated to form small size particles as increasingthe temperature above LCST. For these reasons, theobtained smart copolymers were considered to be potentialgene/drug carriers in biomedical field.
pH-Responsive Drug Delivery Systems Based on Clickable Poly(L-glutamic acid)-Grafted Comb Copolymers
Jianxun Ding,Xuesi Chen,Chaoliang He,Chunsheng Xiao,Jie Chen,Xiuli Zhuang 한국고분자학회 2012 Macromolecular Research Vol.20 No.3
Five pH-responsive alkyne-poly(2-aminoethyl methacrylate)-graft-poly(L-glutamic acid) (alkyne-PAMA-g-PLGA) comb copolymers were synthesized through the ring-opening polymerization (ROP) of γ-benzyl-L-glutamate N-carboxyanhydride (BLG NCA) and the subsequent deprotection of benzyl group from BLG unit. The chemical structures of copolymers were confirmed by proton nuclear magnetic resonance spectra (1H NMR) and Fourier transform infrared spectroscopy (FTIR). The pyrene-probe-based fluorescence technique and transmission electron microscopy (TEM) measurements revealed that the comb copolymers could spontaneously self-assemble into micellar or vesicular nanoparticles in phosphate buffered saline (PBS) at pH 7.4. Doxorubicin (DOX), an anthracycline anticancer drug, was loaded into nanoparticles as a model anticancer drug. The in vitro release results showed that the release behaviors could be altered by adjusting the composition of the comb copolymer and pH of the release medium. In vitro methyl thiazolyl tetrazolium (MTT) assays demonstrated that the copolymers were biocompatible,and DOX-loaded nanoparticles showed effective inhibition of cellular proliferation. Hemolysis tests indicated that the copolymers were also hemocompatible, and that the presence of the copolymers could reduce the hemolysis ratio (HR) of the DOX significantly. In addition, the comb copolymers could be modified through versatile Cu(I)-catalyzed “click chemistry” between the terminal alkyne group and azide-modified functional agents. These properties indicate that the pH-responsive clickable comb copolymers are promising candidates for multifunctional nanocarriers in cancer diagnosis and therapy.
Lee, Yuhan,Lee, Soo Hyeon,Kim, Jee Seon,Maruyama, Atsushi,Chen, Xuesi,Park, Tae Gwan Elsevier 2011 Journal of controlled release Vol.155 No.1
<P><B>Abstract</B></P><P>Development of nano-sized gene delivery vehicles for small interfering RNA (siRNA) delivery is of great importance for their clinical applications such as cancer therapy. Herein, we demonstrate the controlled synthesis of polyethyleneimine (PEI)-coated gold nanoparticles (AuNPs) using catechol-conjugated PEI (PEI-C) for siRNA delivery. Since the conjugated catechol groups are reductive and moderately hydrophobic, PEI-C formed spherical multi-cored micelles in aqueous solution and served as reductive templates for the growth and synthesis of spherical AuNPs with tunable sizes and surface charges. PEI-C was stably anchored on the surface of growing crystal gold seeds with crosslinking, resulting in robust cationic AuNPs. The fabricated PEI-coated AuNPs formed stable complexes with siRNA, and the complexes showed an excellent gene silencing effect in cancer cells. Size and surface charge values of the synthesized AuNPs had a great influence on intracellular uptake and unpacking of siRNA, and the resultant gene silencing efficiency. The PEI-coated AuNPs exhibited an extremely low cytotoxicity due to the reduced density of primary amine groups and the absence of uncomplexed PEI fraction in aqueous solution.</P> <P><B>Graphical Abstract</B></P><P><ce:figure id='f0035'></ce:figure></P>