Rendering polymersomes responsive to pulesd laser irradiation via gold nanoparticle membrane encapsulation and cholesterol-mediated tethering

Synthetic polymeric vesicles, known as polymersomes, hold great promise as carrier vesicles cargo delivery systems. The self-assembly of amphiphilic diblock copolymers into vesicles results in the formation of two compartments: an aqueous lumen which allows for the incorporation of hydrophilic cargo, and a bilayer membrane with a hydrophobic region which can encapsulate non-polar cargo. Gold nanoparticles (AuNPs) have been shown to act as photosensitizers in response to pulsed laser irradiation, allowing for light-responsive membrane disruption for cargo release. In this work, two pathways of AuNP incorporation into nano-polymersomes are investigated. In one method, dodecanethiol-functionalized AuNPs are partitioned into the hydrophobic region of the membrane. It is shown that the concentration of AuNPs present during self-assembly influences vesicle characteristics such as size, percent membrane fill, and surfactant resistance. Furthermore, the concentration of AuNPs is shown to correlate with membrane disruption as a function of laser pulse energy. The second method requires the insertion of a cholesterol membrane anchor to tether AuNPs to the exterior of the vesicle via DNA hybridization. Cholesterol is shown to insert into the membrane and to allow for external tethering. The dual purpose of the polymer membrane as both a compartment and an anchoring region may provide a pathway to greater control over both the size and location of photosensitizers in these promising systems.