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ABSTRACT: The interaction between amino-terminated, and ethylenediamine core poly(amidoamine) (PAMAM) dendrimers and herring sperm DNA
was investigated by various spectroscopic methods including UV spectroscopy, fluorescence spectroscopy, microscopic FTIR-
and circular dichroism (CD-) spectroscopy. Ethidium bromide (EB) is used as a nucleic acid probe for this study. Experimental
results show that PAMAM dendrimers can form stable complexes with DNA and the dendrimers bind to DNA sufficiently strong which
cannot be displaced by EB, and we also found that the formation of the complexes can cause the conformation change of the
DNA secondary structure. According to the Scatchard analysis, the association constant of PAMAM to DNA is calculated to be
2.53 × 104 mol/L−1.
Keywordspoly(amidoamine) dendrimers-DNA-interaction-spectroscopic methods
Chinese Science Bulletin 05/2012; 50(19):2161-2165. · 1.32 Impact Factor
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ABSTRACT: Dendritic polymers are three-dimensional, highly ordered compounds formed by reiterative reaction sequences, and via discrete
stages referred to as generations. To study the spacer effect of low density lipoprotein (LDL) adsorbent, we linked dendrimer
polyamidoamine (PAMAM) generation 1 (G1), generation 3 (G3) and generation 5 (G5) to cellulose beads, respectively, and then
determined the adsorption proportion of the adsorbents with PAMAM decorated with taurine. The result shows that the spacer
with activated multi-points could efficiently improve the adsorption capacity of the adsorbent.
Frontiers of Chemical Engineering in China 04/2012; 2(4):434-438.
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ABSTRACT: The interactions of amino-terminated, and ethylenediamine core poly(amidoamine) (PAMAM) dendrimers and their derivatives with
bovine serum albumin (BSA) were investigated by fluorescence spectroscopy. Experimental results showed that the fluorescence
intensity of BSA decreased after the addition of different modified dendrimers, and the extent of the fluorescence quenching
caused by various modified dendrimers strongly depends upon the different functional groups on their surfaces. We also investigated
the influence of pH and ionic strength on the interaction between various modified dendrimers and BSA. Circular dichroism
(CD) spectroscopic measurements showed that the content of α-helix structure of BSA decreased after the addition of different
modified dendrimers, which indicated that dendrimers induced changes in the secondary structure of BSA.
Keywordspoly(amidoamine) dendrimers-bovine serum albumin-fluorescence quenching-circular dichroism
Chinese Science Bulletin 04/2012; 50(21):2436-2441. · 1.32 Impact Factor
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ABSTRACT: Cell labeling and tracking are becoming increasingly important in the fields of stem cell transplantation. To track the migration and distribution of the implanted cells is critical for understanding the beneficial effects of stem cell therapy. The aim of this study is to synthesize new superparamagnetic nanoparticles and investigate the feasibility of magnetic labeling of bone marrow mesenchymal stem cells (MSCs). Monodisperse hydrophobic magnetite (Fe3O4) nanoparticles were prepared through high temperature decomposition of Fe(acac)3 and a long-chain alcohol. The nanoparticles were further modified with a bipolar surfactant, 2,3-dimercaptosuccinic acid (DMSA) and then transformed into water-soluble iron oxide nanoparticles (WION). The magnetic particles showed uniform size (10 nm), high efficiency and stability in MSCs labeling. The labeled cells were cultured until passage 8, there is no reduction in magnetic tropism and the percentage of labeled cells. The results of MTT proliferation assay and flow cytometry analysis show that the WION are biocompatible. The labeling process does not cause cell death and apoptosis, and has no side effect on growth capacity of the cells. In conclusion, the successful and stable labeling of MSCs and the efficient magnetic tropism indicate that this WION can be used for tracking of MSCs in future MSCs-based stem cell therapy.
Journal of Nanoscience and Nanotechnology 05/2011; 11(5):3749-56. · 1.56 Impact Factor
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ABSTRACT: A novel class of non-viral gene vectors consisting of low molecular weight poly(ethylene imine) (PEI) (molecular weight 800 Da) grafted onto degradable linear poly(ethylene glycol) (PEG) analogs was synthesized. First, a Michael addition reaction between poly(ethylene glycol) diacrylates (PEGDA) (molecular weight 258 Da) and d,l-dithiothreitol (DTT) was carried out to generate a linear polymer (PEG-DTT) having a terminal thiol, methacrylate and pendant hydroxyl functional groups. Five PEG-DTT analogs were synthesized by varying the molar ratio of diacrylates to thiols from 1.2:1 to 1:1.2. Then PEI (800 Da) was grafted onto the main chain of the PEG-DTTs using 1,1'-carbonyldiimidazole as the linker. The above reaction gave rise to a new class of non-viral gene vectors, (PEG-DTT)-g-PEI copolymers, which can effectively complex DNA to form nanoparticles. The molecular weights and structures of the copolymers were characterized by gel permeation chromatography, (1)H nuclear magnetic resonance and Fourier transform infrared spectroscopy. The size of the nanoparticles was<200 nm and the surface charge of the nanoparticles, expressed as the zeta potential, was between+20 and+40 mV. Cytotoxicity assays showed that the copolymers exhibited much lower cytotoxicities than high molecular weight PEI (25 kDa). Transfection was performed in cultured HeLa, HepG2, MCF-7 and COS-7 cells. The copolymers showed higher transfection efficiencies than PEI (25 kDa) tested in four cell lines. The presence of serum (up to 30%) had no inhibitory effect on the transfection efficiency. These results indicate that this new class of non-viral gene vectors may be a promising gene carrier that is worth further investigation.
Acta biomaterialia 07/2010; 6(7):2650-7. · 3.98 Impact Factor
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ABSTRACT: Phage display technology has been demonstrated to be a powerful tool for screening useful ligands that are capable of specifically binding to biomarkers on the surface of tumor cells. The ligands found by this technique, such as peptides, have been successfully applied in the fields of early cancer diagnostics and chemotherapy. In this study, a novel nonsmall cell lung cancer-targeting peptide (LCTP, sequence RCPLSHSLICY) was screened in vivo using a Ph.D.-C7C(™) phage display library. In order to develop a universal tumor-targeting drug carrier, the LCTP and fluorescence-labeled molecule (FITC) were conjugated to an acetylated polyamidoamine (PAMAM) dendrimer of generation 4 (G4) to form a PAMAM-Ac-FITC-LCTP conjugate. The performance of the conjugate was first tested in vitro. In vitro results of cell experiments analyzed by flow cytometry and inverted fluorescence microscopy indicated that PAMAM-Ac-FITC-LCTP was enriched more in NCI-H460 cells than in 293T cells, and cellular uptake was both time- and dose-dependent. The tissue distribution of the conjugate in athymic mice with lung cancer xenografts was also investigated to test the targeting efficiency of PAMAM-Ac-FITC-LCTP in vivo. The results showed that LCTP can effectively facilitate the targeting of PAMAM-Ac-FITC-LCTP to nonsmall cell lung cancer cells and tumors. These results suggest that the LCTP-conjugated PAMAM dendrimer might be a promising drug carrier for targeted cancer diagnosis and treatment.
International Journal of Nanomedicine 01/2010; 6:59-69. · 3.13 Impact Factor
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ABSTRACT: Polyamidoamine (PAMAM) dendrimers represent one of the most efficient polymeric gene carriers. This study describes a new family of PAMAM dendrimers that can be synthesized using a Pentaerythritol derivative (PD) as a core that possesses 12 branches. This new approach in the synthesis of divergent dendrimers provided a rapid increase in the number of branches, which made it easier to obtain dendrimers with high generation and large enough molecular size. The PD dendrimers of generations 3-5 synthesized in this study could efficiently condense DNA into nanoscale complexes with slightly positive charges. Their transfection efficiency was evaluated in different cell lines. These PD dendrimers were found to show higher transfection efficiency, but much lower cytotoxicity, than the commercial nonviral gene carriers polyethyleneimine (PEI), polylysine (PLL), and PAMAM dendrimers with an ethylenediamine core (generations 5 and 7). The results indicate that, with high transfection efficiency and low cytotoxicity, the PD dendrimers hold promise as novel nonviral gene carriers.
Biomacromolecules 03/2009; 10(3):617-22. · 5.48 Impact Factor
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ABSTRACT: G250 is a tumor associated antigen that is found on > 90% of renal cell carcinoma (RCC). In order to develop a highly targeting gene vector for RCC gene therapy, G250 monoclonal antibody was prepared, purified and characterized. The antibody was chemically bound to Polyethylenimine (PEI) to form the IgG-PEI conjugate. The conjugate is capable of forming DNA complexes in the size of nano meters and with a narrow size distribution. The targeting effect and transfection efficiency were tested on five cell lines, ketr 3, Hela, ACHN, HepG2, and smooth muscle cells. The transfection was quantitatively determined by fluorescence activated cell sorting (FACS) and luciferase assay. The FACS results show that for G250 positive cells ketr 3 and Hela, the transfection efficiency of IgG-PEI are 2-fold higher than that of PEI. But for G250 negative cells, antibody modification has no effect on transfection. The expression of luciferase in ketr 3 cells which is expressed as enzyme activity is 15-fold and 61-fold higher than that in ACHN and SMC, respectively. In the presence of free antibody, the targeting effect of IgG-PEI is impaired and the transfection efficiency is normalized. It indicates that G250 antibody is an ideal targeting ligand for delivery of genes into RCC. Application of this IgG-PEI conjugate in RCC gene therapy will be of great interest.
Journal of Controlled Release 05/2008; 127(2):173-9. · 5.73 Impact Factor
