Interfacial analysis of siRNA complexes with poly-ethylenimine (PEI) or PAMAM dendrimers in gene delivery

Publication date: 1 October 2017 Source:Colloids and Surfaces B: Biointerfaces, Volume 158 Author(s): Patrick K.C. Chang, Clive A. Prestidge, Kristen E. Bremmell Solution and interfacial analysis has been employed to gain insight into the complexation of siRNA using either G4 PAMAM dendrimers or 25kDa branched poly-ethylenimine (bPEI). The size, charge and shape/structure of the complexing agents were probed using atomic force microscopy (AFM), circular dichroism spectrometry (CD), dynamic light scattering (DLS), and gel electrophoresis (GE). The binding capability of these cationic polymers to the siRNA molecule, subsequently controls the surface/adsorption behaviour of the complexes to a negatively charged surface. G4 PAMAM dendrimers bind to the major groove of the siRNA structure, while bPEI binds to both major and minor groove. PAMAM-siRNA complexes form a thin uniform surface film with adsorption of monomeric particles, whilst bPEI-siRNA complexes adsorb as particles in random orientations at low bPEI concentration and form network structures across the surface at high charge ratio. This is due to their ability to bind to both regions within siRNA. This new understanding of the interfacial behaviour of siRNA complexes correlates with observations of cellular transfection and can be used in the design of optimal transfection agents. Graphical abstract

Source: Colloids and Surfaces B: Biointerfaces - July 16, 2017 Category: Biochemistry Source Type: research