Nonviral gene delivery: gemini bispyridinium surfactant-based DNA nanoparticles.

The interaction with a model membrane, the formation of DNA nanoparticles, and the transfection ability of a homologous series of bispyridinium dihexadecyl cationic gemini surfactants, differing in the length of the alkyl spacer bridging the two pyridinium polar heads in the 1 and 1' positions (P16-n with n = 3, 4, 8, 12), have been studied by means of differential scanning calorimetry (DSC), atomic force microscopy, electrophoresis mobility shift assay, and transient transfection assay measurements. The results presented here show that their performance in gene delivery is strictly related to their structure in solution. For the first time the different transfection activities of the compounds can be explained by referring to their thermodynamic properties in solution, previously studied.

New gluconamide-type cationic surfactants: Interactions with DNA and lipid membranes.

New linear cationic surfactants - 2-(alkyldimethylammonio)ethylgluconamide bromides, denoted as CnGAB, n=10, 12, 14 and 16 - were synthesized from natural resources and characterized with respect to their potential as gene-delivery agents in gene therapy applications. Interactions with plasmid DNA and with model membranes were studied both experimentally and theoretically. The compounds with n=12, 14 and 16 show exponentially increasing ability to fully condense DNA.

Prediction of critical micelle concentration of nonionic surfactants by a quantitative structure - property relationship.

A quantitative structure - property relationship (QSPR) was used to predict the critical micelle concentration (cmc) of nonionic surfactants. The relation was developed for a diverse set of 23 nonionic surfactants (r = 0.99, F-test = 1042.

Aggregation studies of n-alkanoyl-N-methyllactitolamine surfactants.

The micellization processes of n-alkanoyl-N-methyllactitolamines (CnMeLA) were studied by means of isothermal titration calorimetry (ITC) and compared with those of decanoyl-N-methyl glucamide (MEGA-10). The critical micelle concentrations (cmc), the enthalpies (deltaH(m)) and the entropies (deltaS(m)0) of micellization as well as the contributions of the head groups to the Gibbs free energies (deltaG(m)0 (hy)) were calculated. The molecular modeling studies including the conformational analysis and calculations of some molecular descriptors related to hydrophilic and hydrophobic interactions were done to elucidate the experimental results at the atomic level.

Thermodynamics and biological properties of the aqueous solutions of new glucocationic surfactants.

Thermodynamic properties of aqueous solutions of newly synthesized compounds, namely, N-[2-(beta-D-glucopyranosyl)ethyl]-N,N-dimethyl-N-alkylammonium bromides with hydrophobic tails of 12 (C12DGCB) and 16 (C16DGCB) carbon atoms, determined as a function of concentration by means of direct methods, are reported here. Dilution enthalpies, densities, and sound velocities were measured at 298 K, allowing for the determination of apparent and partial molar enthalpies, volumes, and compressibilities. Changes in thermodynamic quantities upon micellization were derived using a pseudophase-transition approach.