Person:
Junquera González, María Elena

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First Name
María Elena
Last Name
Junquera González
URI
https://hdl.handle.net/20.500.14352/76281
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Químicas
Department
Química Física
Area
Química Física
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2012 - 20142
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Author: Barrán Berdón, Ana × Has files: false ×

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    Cationic gemini lipids containing polyoxyethylene spacers as improved transfecting agents of plasmid DNA in cancer cells
    (Journal of Materials Chemistry B, 2014) Barrán Berdón, Ana ; Misra, Santosh; Datta, Sougata; Muñoz Úbeda, Mónica; Kondaiah, Paturu; Junquera González, María Elena; Bhattacharya, Santanu; Aicart Sospedra, Emilio
    Lipoplex nano-aggregates have been analyzed through biophysical characterization (electrostatics, structure, size and morphology), and biological studies (transfection efficiency and cell viability) in five cancer cell lines. Lipoplexes were prepared from pEGFP-C3 plasmid DNA (pDNA) and mixed liposomes, constituted by a zwitterionic lipid (DOPE) and a gemini cationic lipid (GCL) synthesized in this work, [bis(hexadecyl dimethyl ammonium) oxyethylene], referred to as (C16Am)2(C2O)n, (where n is the oxyethylene spacer length, n ¼ 1, 2 or 3, between the ammonium heads). Cryo-TEM micrographs show nano-aggregates with two multilamellar structures, a cluster-type (at low-to-medium GCL composition) and a fingerprint-type that coexists with the cluster-type at medium GCL composition and appears alone at high GCL composition. SAXS diffractograms show that these lipoplexes present three lamellar structures, two of them coexisting at low and high GCL composition. The optimized transfection efficiency (TE) of pDNA was higher for lipoplexes containing GCLs with a longer (n ¼ 3) or shorter (n ¼ 1) polyoxyethylene spacer, at high GCL composition (a ¼ 0.7) with low charge ratio (reff ¼ 2). In the all cancer cell lines studied, the TE of the optimized formulations was much better than those of both lipofectamine 2000 and lipoplexes with GCLs of the bis(hexadecyl dimethyl ammonium) alkane series recently reported. Probably, (a) the coexistence of two lamellar structures at high GCL composition synergizes the TE of these lipid vectors, (b) the orientation of the polyoxyethylene region in (C16Am)2(C2O)3/DOPE may occur in such a way that the spacing between two cationic heads becomes smaller than that in (C16Am)2(C2O)2/DOPE which is poor in terms of TE, and (c) the synergistic interactions between serum proteins and (C16Am)2(C2O)n/DOPE-pDNA lipoplexes containing a polyoxyethylene spacer improve TE, especially at high GCL content. Lipoplexes studied here show very low levels of toxicity, which confirm them as improved vectors of pDNA in gene therapy
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    Ribbon-type and cluster-type lipoplexes constituted by a chiral lysine based cationic gemini lipid and plasmid DNA
    (Soft Matter, 2012) Barrán Berdón, Ana ; Muñoz Úbeda, Mónica; Aicart Ramos, Clara; Pérez, Louedes; Infante, María Rosa; Castro Hartmann, Pablo; Martín Molina, Alberto; Aicart Sospedra, Emilio; Junquera González, María Elena
    Lipoplexes constituted by plasmid DNA pEGFP-C3 (pDNA) or linear double-stranded calf thymus DNA (ctDNA) and mixed cationic liposomes consisting of several percentages of the cationic lysine derived lipid C6(LL)2 and the zwitterionic lipid 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) have been analyzed by both experimental and theoretical approaches. Experimental studies, consisting of electrophoretic mobility/zeta potential, small angle X-ray scattering (SAXS), cryogenic transmission electron microscopy (cryo-TEM), negatively stained transmission electron microscopy (NS-TEM), and GelRed f1uorescence intercalation assays, have been carried out at several liposome and lipoplex compositions, defined in terms of cationic lipid molar fraction and either the mass or charge ratios of the lipoplex. The electrochemical study confirms that, in the presence of the mixed lipids and in contrast with what has usually been found for linear DNA, the plasmid DNA is compacted with a large number of its Na+ counterions, thus yielding a much lower effective negative charge (q pDNA) than that for ctDNA (q ctDNA), as reported recently by us (J. Am. Chem. Soc., 2011) for other lipoplexes. This finding is revealed as crucial for an optimum and efficient lipoplex preparation, since a lower effective negative charge implies a lower quantity of cationic lipid and, accordingly, a potential lower cytotoxicity. TEM experiments reveal a complex scenario of multilamellar nanostructures, from ribbon-type (typically present for chiral lipids) to cluster-type structures (usually found in cationic lipid/ DOPE systems), the composition of the mixed liposome playing an important role in the final morphology of the lipoplex. SAXS diffractograms confirm the existence of these two types of multilamellar structures through a deconvolution process of the first peak of diffractograms into two overlapping bands. On the other hand, a theoretical complexation model is employed to determine the net charge of the lipoplexes studied in this work. The model allows analysis and comparison of the electrochemical behaviour of lipoplexes containing linear DNA vs. those constituted by a supercoiled DNA, confirming the experimental findings