ABSTRACT Five novel cationic lipids, the polar head group of which was attached to the cholesterol backbone via a tertiary carbamate linker, were synthesized and their physicochemical properties were compared to their transfection efficiencies. Transfection activity of the primary amine analog was highest among the series, while the quaternary ammonium iodide salt was essentially transfection incompetent. Contrary to DC-Chol, methyl and ethyl carbamoyl derivatives of DC-Chol mediated high levels of transfection in the absence of DOPE. Ionization of the cationic assemblies in 40 mM Tris buffer pH 7.2 exactly correlated with the competitive nature of the inductive and steric effects of the methyl groups on the aliphatic nitrogen of the lipids’ polar moiety. Interestingly, the pH interaction zone of all lipid dispersions at 25°C was extended by ± 2 pH units from the pKa, while the pKa of the cationic lipids determined in mixed vesicles composed of 90 % DOPC and cholesterol was approximately 1.3 to 1.5 times higher than that of pure cationic assemblies. The interaction of cationic lipids with plasmid DNA was correlated with pKa, but not the transfection activity.
Cite this paper
nullAcheampong, S. and Savva, M. (2011) Ionization and transfection activity of n-methyl-substituted carbamoyl-cholesterol derivatives. Journal of Biophysical Chemistry, 2, 53-62. doi: 10.4236/jbpc.2011.22008.
 Gao, X.A. and Huang, L. (1991) A novel cationic liposome reagent for efficient transfection of mammalian cells. Biochemical and Biophysical Research Communications, 179, 280-285.
Middleton, P.G., Caplen, N.J., Gao, X., Huang, L., Gaya, H., Geddes, D.M. and Alton, E.W.F.W. (1994) Nasal application of the cationic liposome DC-Chol: DOPE does not alter ion transport, lung function or bacteria growth. European Respiratory Journal, 7, 442-445.
Blagbrough, I.S., Geall, A.J. and Neal, A.P. (2003) Polyamines and novel polyamine conjugates interact with DNA in ways that can be exploited in non-viral gene therapy. Biochemical Society Transactions, 31, 397-406.
Griesenbach, U., Kitson, C., Garcia, S.E., Farley, R., Singh, C., Somerton, L., Painter, H., Smith, R.L., Gill, D. R., Hyde, S.C., Chow, Y.-H., Hu, J., Gray, M., Edbrooke, M., Ogilvie, V., MacGregor, G., Scheule, R.K., Cheng, S.H., Caplen, N.J. and Alton, E.W.F.W (2006) Inefficient cationic lipid-mediated siRNA and antisense oligonucleotide transfer to airway epithelial cells in vivo. Respiratory Research, 7, 1-15.
Vigneron, J.-P., Oudrhiri, N., Fauquet, M., Vergely, L., Bradley, J.-C., Basseville, M., Lehn, P. and Lehn, J.-M. (1996) Guanidinium-cholesterol cationic lipids: Efficient vectors for the transfection of eukaryotic cells. Proceedings of the National Academy of Sciences of the United States of America, 93, 9682-9686.
Fang, N., Wang, J., Mao, H.-Q., Leong, K. W. and Chan, V. (2003) BHEM-Chol/DOPE liposome induced perturbation of phospholipid bilayer. Colloids and Surfaces B: Biointerfaces, 29, 233-245.
Ghosh, Y.K, Visweswariah, S.S. and Bhattacharya, S. (2000) Nature of linkage between the cationic head group and cholesterol skeleton controls gene transfection efficiency. Federation of European Biochemical Societies Letters, 473, 341-344.
Bajaj, A., Mishra, S.K., Kondaiah, P. and Bhattacharya, S. (2008) Effect of the headgroup variation on the gene transfer properties of cholesterol based cationic lipids possessing ether linkage. Biochimica et Biophysica Acta: Biomembranes, 1778, 1222-1236.
Esposito, C., Generosi, J., Mossab, G., Masotti, A. and Castellano, A.C. (2006) The analysis of serum effects on structure, size and toxicity of DDAB-DOPE and DC-Chol-DOPE lipoplexes contributes to explain their different transfection efficiency. Colloid Surface B Biointerfaces, 53, 187-192.
Koltover, I., Salditt, T. and Safinya, C.R. (1999) Phase Diagram, Stability, and Overcharging of Lamellar Cationic Lipid-DNA Self-Assembled Complexes. Biophysical Journal, 77, 915-924.
Felgner, P.L., Gadek, T.R., Holm, M., Roman, R., Chan, W., Wenz, M., Northorp, J.P., Ringold, G.M. and Danielsen, M. (1987) Lipofection: A highly efficient lipid-mediated DNA transfection procedure. Proceedings of the National Academy of Sciences of the United States of America, 84, 7413-7417.
Israelachvili, J.N., Marcelja, S. and Horn, R.G. (1980) Physical principles of membrane organization. Quarterly reviews of biophysics, 13, 121-200.
Gruner, S.M., Cullis, P.R., Hope, M.J. and Tilcock, P.S. (1985) Lipid polymorphism: the molecular basis of nonbilayer phases. Annual Review of Biophysics and Biophysical Chemistry, 14, 211.
Kearns, M., Donkor, A.M. and Savva, M. (2008) Structure—Transfection activity studies of novel cationic cholesterol-based amphiphiles. Molecular Pharmaceutics, 5, 128-139. doi:10.1021/mp700131c
Sambrook, J., Fritsch, E.F. and Maniatis, T. (1989) Molecular Cloning: A Laboratory Manual. 2nd Edition, Cold Spring Harbor Laboratory Press, New York.
Savva, M. and Acheampong, S. (2009) The interaction energies of cholesterol and 1,2-dioleoyl-phosphoetha-nolamine in spread mixed monolayers at the air-water interface. Journal of Physical Chemistry B, 113, 9811-9820. doi:10.1021/jp902748s
Spelios, M. and Savva, M. (2008) Novel N,N′-1,3-diaminopropyl-2-carbamoyl bivalent cationic lipids for gene delivery-synthesis, in vitro transfection activity, and physicochemical characterization. Federation of European Biochemical Societies Journal, 275, 148-162.
Wang, J.L. and Edelman, G.M. (1971) Fluorescent probes for confromational states of proteins. Journal of Biological chemistry, 246, 1185-1191.
Bailey, A.L. and Cullis, P.R. (1994) Modulation of membrane fusion by asymmetric transbilayer distributions of amino lipids. Biochemistry, 33, 12573-12580.
Asokan, A. and Cho, M.J. (2003) Cytosolic delivery of macromolecules II. Mechanistic studies with pH-sensitive morpholine lipids. Biochimica et Biophysica Acta: Biomembranes, 161, 151-160.
Heyes, J., Palmer L., Bremner, K. and MacLachlan, I. (2005) Cationic lipid saturation influences intracellular delivery of encapsulated nucleic acids. Journal of Controlled Release, 107, 276-287.
Marchington, A.F., Moore, S.C.R. and Richards, W.G. (1979) The inductive effect in molecules and ions. Journal of the American Chemical Society, 101, 5529-5532. doi:10.1021/ja00513a012
Miessler, G.L. and Tarr, D.A. (2003) Inorganic Chemistry, Prentice Hall, New Jersey.