title: Nonviral gene delivery: gemini bispyridinium surfactant-based DNA nanoparticles.
abstract: 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. The compound with a spacer formed by four carbon atoms, showing unexpected enthalpic properties vs concentration in solution, is the only one giving rise to a transfection activity comparable to that of the commercial reagent, when formulated with L-α-dioleoylphosphatidylethanolamine. We suggest that P16-4 behaves like molecular tongs able to grip basic groups near each other, allowing the formation of compact and nearly spherical DNA particles. The compound with the longest spacer gives rise to loosely condensed structures by forming a sort of bow, not able to give rise to transfection notwithstanding the double positive charge of the molecule. On the other hand, DSC measurements on synthetic membranes show that the compounds with the shortest spacers (three and four methylene groups) practically do not interact with the 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine membrane, while compounds P16-8 and, particularly, P16-12 induce the formation of surfactant-rich and surfactant-poor domains in the membrane, without showing any peculiarity for compound P16-4. This could suggest that the mechanisms involved in the interaction with the model membrane and in gene delivery are substantially different and could strike a blow for an endocytosis mechanism for the internalization in the cell of the DNA nanoparticles.
authors.affiliation: Department of Pharmacy, University of Parma , Parco Area delle Scienze 27/A, 43124 Parma, Italy.
authors.forename: Emilia
authors.initials: E
authors.lastname: Fisicaro
authors.forename: Carlotta
authors.initials: C
authors.lastname: Compari
authors.forename: Franco
authors.initials: F
authors.lastname: Bacciottini
authors.forename: Laura
authors.initials: L
authors.lastname: Contardi
authors.forename: Nadia
authors.initials: N
authors.lastname: Barbero
authors.forename: Guido
authors.initials: G
authors.lastname: Viscardi
authors.forename: Pierluigi
authors.initials: P
authors.lastname: Quagliotto
authors.forename: Gaetano
authors.initials: G
authors.lastname: Donofrio
authors.forename: Bożenna
authors.initials: B
authors.lastname: Różycka-Roszak
authors.forename: Paweł
authors.initials: P
authors.lastname: Misiak
authors.forename: Edyta
authors.initials: E
authors.lastname: Woźniak
authors.forename: Francesco
authors.initials: F
authors.lastname: Sansone
mesh_terms: D002152:Calorimetry, Differential Scanning; D045744:Cell Line, Tumor; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D006801:Humans; D018625:Microscopy, Atomic Force; D053758:Nanoparticles / Q000737:chemistry*; D010957:Plasmids / Q000378:metabolism*; D011726:Pyridinium Compounds / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*; D013816:Thermodynamics; D014162:Transfection
chemical_list: D011726:Pyridinium Compounds; D013501:Surface-Active Agents; D004247:DNA