Successive Outermost-to-Core Shell Directionality of the Protonation of Poly(Propyl Ether Imine) Dendritic Gene Delivery Vectors

The protonation behaviour of polycationic compounds have direct relevance to their ability to condense and deliver nucleic acids. This report pertains to a study of the protonation behaviour of polycationic poly(propyl ether imine) (PETIM) dendritic gene delivery vectors, that are constituted with tertiary amine core moiety and branch sites, n-propyl ether linkages and primary amine peripheries. The ability of this series of dendrimers to condense nucleic acids and mediate endosomal escape was studied by unravelling the protonation behaviour of the dendrimers aided by pH-metric titrations, 1H and 15N NMR spectroscopies. The results demonstrate protonation of the primary and tertiary amines of outermost-to-core shells occurring in a successive step-wise fashion, in contrast to other polycationic vectors. Theoretical calculations based on the Ising model rationalize further the finer details of protonation at each shell. The protonation pattern correlates with the endosomal buffering and nucleic acid condensation properties of this PETIM based dendritic gene delivery vectors. The study establishes that the protonation behaviour is a critical and essential parameter in order to assess the gene condensation and delivery vector properties of a polycationic compound.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author