A Novel Dendrimeric “Glue” for Adhesion of Phosphatidyl Choline-Based Liposomes

Abstract

The interaction of phosphatidyl choline-cholesterol liposomes incorporating dihexadecyl phosphate as recognizable lipid with complementary guanidinylated diaminobutane poly(propylene imine) dendrimers of the fourth and fifth generation afforded liposome-dendrimer aggregates which were redispersed by the addition of an excess of a phosphate buffer. The higher generation dendrimeric derivative proved more effective when interacted with liposomes. This behavior was attributed to multivalent effects, which, as generally established, enhance the reactivity of multifunctional particles. Turbidimetry, atomic force microscopy (AFM) and optical microscopy were used for investigating the interaction of the complementary particles while the redispersion of the aggregates was studied by transmission electron microscopy (TEM). Liposomal membrane stability in the collapse and redispersion processes was assessed by the calcein fluorescence method, TEM, and AFM.

Physico-chemical Studies on the Interaction of Dendrimers with Lipid Bilayers. 1. Effect of Dendrimer Generation and Liposome Surface Charge

“…Effectiveness of the interaction process between dendrimer and liposomes were thus assessesed by turbidity measurement. This method has extensively been used by others 32,33,37 . Figure 1 shows the effect of different generation PAMAM dendrimers on the absorbance enhancement of SLC CHOL liposome.…”

“…Thus turbidity and size of the liposomal dispersion are expected to increase. According to the proposition of Sideratou et al 39,40 , dendrimers can act as glue to the liposomes. However the appearances of maxima in the present set of studies are an uncommon phenomenon, which have not previously been experienced by others.…”

“…Weak van der Waals types of forces also contribute to the interaction. Basically dendrimers get adsorbed onto the liposome surface by virtue of electrostatic interaction 32,33 . Hence one should expect a change in the zeta potential during the dendrimer-liposome interaction.…”

Interaction between complementary liposomes: a process leading to multicompartment systems formation

“…Molecules bearing more than one recognizable moieties can be employed for binding liposomes. This is the case, for instance, with multifunctional guanidinylated dendrimers (Sideratou et al, 2002a), which are considered as kind of 'molecular glue.' Returning to the interactions between liposomes, adhesion occurs at the second stage and the complementary liposomes are simply conjoined with retention of their inner compartments.…”

Creating Functional Vesicle Assemblies from Vesicles and Nanoparticles

“…Paleos and coworkers have conducted extensive studies on the formation of vesicle aggregates and have produced large vesicle aggregates by mixing phosphate-lipid doped vesicles with guanidylated dendrimers (16) or polyarginine (17). Very large aggregates (>1000 nm diameter) resulted from the addition of polyarginine to vesicles (100 nm diameter) bearing 5% mol/ mol di(hexadecyl)phosphate, but heating to the bilayer melting temperature (T m ) resulted in partial penetration of the polypeptide into the bilayer.…”