Photocontrolled Self-Assembly and Disassembly of Block Ionomer Complex Vesicles: A Facile Approach toward Supramolecular Polymer Nanocontainers

Abstract

A new concept of designing a photocontrollable supramolecular polymer nanocontainer through the electrostatic association between an azobenzene-containing surfactant (AzoC10) and a double-hydrophilic block ionomer, poly(ethylene glycol)-b-poly(acrylic acid) (PEG(43)-PAA(153)), is described. Such a block ionomer complex can self-assemble in aqueous solution and form vesicle-like aggregates, which are composed of a poly(ethylene glycol) corona and a poly(acrylic acid) shell associated with azobenzene-containing surfactant. The photoisomerization of azobenzene moieties in the block ionomer complex can reversibly tune the amphiphilicity of the surfactants, inducing the disassembly of the vesicles. Such block ionomer complex vesicles are further evaluated as nanocontainers capable to encapsulate and release guest solutes on demand controlled by light irradiation. For example, the vesicles encapsulating the fluorescein sodium display clear spherical images observed by fluorescence microscopy. However, such fluorescence-marked images disappear after releasing the solute from the vesicles triggered by the UV light. Such novel materials are of both basic and practical significance, especially as prospective nanocontainers for cargo delivery.

Vesicle formation in mixture of a PEO-PPO-PEO block copolymer (Pluronic P123) and a nonionic surfactant (Span 65) in water

“…The PEO-PPO-PEO block copolymer vesicles with high stability should provide various opportunities for material, biological and medical applications such as drug delivery system [25]. Thus, several approaches have been attempted to improve the stability of PEO-PPO-PEO block copolymer vesicles, polymer vesicles (polymersomes) and nonionic surfactant vesicles (noisomes): utilization of hydrophobic block copolymers such as poly(ethylene oxide)-poly(ethyl ethylene) [26], poly(ethylene oxide)-cholesterol [27], poly(ethylene oxide)-poly(propylene oxide)-poly(lactic acid) [28] or mixing of polymers, surfactants and hydrophobic components, for example, Pluronic P123/sodium dodcyl sulfate/NaF mixture [29], Pluronic L121/Pluronic P85/pentaerythritol tetraacrylate mixture [30], a poly(ethylene glycol)/Tween 80/Span 80 mixture [31][32][33][34][35], nonionic surfactant/cholesterol mixture [36,37], poly(ethylene glycol)-b-poly(sodium methacrylate)/cationic surfactant mixture [38], poly(ethylene glycol)-b-poly(acrylic acid)/azobenzene-containing surfactant mixture [39] and poly(ethylene oxide)-b-poly(1,2-butylene oxide)/ionic surfactant mixture [40].…”

Macromolecular self-assembly and nanotechnology in China

“…They can self-assemble in aqueous solution to form vesicle-like aggregates. The photoisomerization of azobenzene moieties in the polymeric supra-amphiphiles can reversibly tune the amphiphilicity of the supra-amphiphiles, inducing disassembly of the vesicles [17]. In another system, they reported the fabrication of a UV responsive polymeric supra-amphiphile formed by an anionic malachite green derivative and the cationic double hydrophilic block copolymer poly(ethylene glycol)-block-poly(L-lysine hydrochloride) (PEG-b-PLKC) [18].…”

Synthesis, Characterization and Spectroscopic Studies on Azo-Hydrazone Tautomerism and Acidity Constants of Certain 4-(Phenyldiazenyl) Benzene-1,3-Diol Derivatives

“…Consequently, new photochemical research has been developed [1][2][3][4]. Azo groups exhibit thermal and photochemical switching through their conformers; this principle has been applied when building sensory systems [5][6][7][8][9]. Azobenzene chromophores undergo reversible cis-trans photoisomerization, showing nonlinear optical properties, as well as light-induced dichroism and birefringence [7].…”