Modulation of Guest Partitioning Within Dendrimer–Surfactant Supramolecular Assemblies

Abstract

Electrostatic interactions are used to create a template-assisted supramolecular assembly consisting of a polymeric dendrimer at the core and amphiphilic substrates on the periphery. The dendrimer generation and the chemical structure of the amphiphiles are varied to construct multiple and distinct microenvironments within the dendrimer-ligand complex for encapsulation of small guest molecules. In particular, these investigations employ a guest molecule that is a neutral fluorescent probe that exhibits an emission wavelength with an extreme sensitivity to the polarity of its surroundings. Partitioning of the fluorophore within the various microregions of the dendrimer-surfactant supramolecular complex is distinguished by the characteristic emission wavelengths of the overlapping Gaussian functions comprising the overall fluorescence spectrum. The observed variations in the prodan emission spectrum suggest interaction of prodan at protonated amino groups (460-nm emission), within dendritic branches and surfactant tails (490-nm emission), and in interior regions of the dendrimer core (430-nm emission). We demonstrate that the positioning of the guest molecule within the supramolecular complex can be modulated through the selection of dendrimer generation, surfactant chain length, and dendrimer : surfactant concentration ratio.

New Insights into the Interactions between Dendrimers and Surfactants: 2. Design of New Drug Formulations Based on Dendrimer−Surfactant Aggregates

“…The structure, nature, and interaction mechanism of the dendrimer−surfactant aggregates were reported by several groups. ,− The aggregates create a template-assisted supramolecular assembly consisting of a dendrimer at the core and amphiphilic surfactants on the surface by electrostatic interactions. , Surfactants can also penetrate the surface charge barriers of dendrimers and localize in their interior cavities by hydrophobic interactions or hydrogen - bonding interactions . Although solubilization of fluorescent dyes such as pyrene and prodan by the dendrimer−surfactant aggregations was carried out to investigate the guest partition within the supramolecular assemblies, , no study reported the applications of the aggregates as drug carriers. It was reported that both dendrimers and surfactants can help drugs to penetrate through skin barriers, which is the main challenge to transdermal drug delivery. − The dendrimer−surfactant aggregates are expected to increase the drug loading efficiency, adhesive property, and penetration ability of dendrimers, modulate the drug release behaviors .…”

“…14,15 Surfactants can also penetrate the surface charge barriers of dendrimers and localize in their interior cavities by hydrophobic interactions or hydrogen-bonding interactions. 6 Although solubilization of fluorescent dyes such as pyrene and prodan by the dendrimersurfactant aggregations was carried out to investigate the guest partition within the supramolecular assemblies, 10,16 no study reported the applications of the aggregates as drug carriers. It was reported that both dendrimers and surfactants can help drugs to penetrate through skin barriers, which is the main challenge to transdermal drug delivery.…”

Competitive Supramolecular Encapsulation of Amphiphilic Hyperbranched Polymers Made from A2 and BB`2 Type Monomers. 1. Polyaddition of 1-(2-aminoethyl)piperazine to Divinyl Sulfone

“…Gao et al reported that aliphatic chainmodified hyperbranched poly(sulfone-amine) (HPSA) and poly(amido-amine) (HPAMAM) could trap water-soluble dyes into chloroform phase efficiently [46][47][48][49]. Besides this kind of molecule-level encapsulation, Edirisinghe et al [50][51][52][53] also reported some new methods to prepare different kinds of encapsulated microspheres.…”

Fluorescence Delineation of the Surfactant Microstructures in the CTAB−SOS−H2O Catanionic System

“…Deconvolution of the overall prodan fluorescence emission spectrum into a sum of overlapping Gaussian functions enables an interpretation of the location of prodan within discrete microdomains of different relative polarities. We have used prodan to characterize the noncovalent interactions that influence the partitioning of guest molecules within surfactant aggregates such as aqueous micelles, ,, reverse micelles, − and unilamellar vesicles 45,47 and within supramolecular assemblies of polymeric dendrimers and surfactants . The polarity and water accessibility of the microregions of surfactant aggregates differ considerably and give rise to distinct emission λ max .…”

“…We have used prodan to characterize the noncovalent interactions that influence the partitioning of guest molecules within surfactant aggregates such as aqueous micelles, 42,44,45 reverse micelles, [43][44][45] and unilamellar vesicles 45,47 and within supramolecular assemblies of polymeric dendrimers and surfactants. 48 The polarity and water accessibility of the microregions of surfactant aggregates differ considerably and give rise to distinct emission λ max . The fluorescence signature of prodan in these surfactant aggregates suggests that several intermolecular forces influence probe distribution, including hydrophobic interactions, van der Waals (i.e., dipole-dipole) forces, and electrostatic association between the π electrons of the aromatic ring of prodan and cationic surfactant headgroups.…”