Direct Visualization of Vesicle Disassembly and Reassembly Using Photocleavable Dendrimers Elucidates Cargo Release Mechanisms.

ABSTRACT

Release of cargo molecules from cell-like nanocarriers can be achieved by chemical perturbations, including changes to pH and redox state and via optical modulation of membrane properties. However, little is known about the kinetics or products of vesicle breakdown due to limitations in real-time imaging at nanometer length scales. Using a library of 12 single-single type photocleavable amphiphilic Janus dendrimers, we developed a self-assembling light-responsive dendrimersome vesicle platform. A photocleavable ortho-nitrobenzyl inserted between the hydrophobic and hydrophilic dendrons of amphiphilic Janus dendrimers allowed for photocleavage and disassembly of their supramolecular assemblies. Distinct methods used to self-assemble amphiphilic Janus dendrimers produced either nanometer size small unilamellar vesicles or micron size giant multilamellar and onion-like dendrimersomes. In situ observation of giant photosensitive dendrimersomes via confocal microscopy elucidated rapid morphological transitions that accompany vesicle breakdown upon 405 nm laser illumination. Giant dendrimersomes displayed light-induced cleavage, disassembling and reassembling into much smaller vesicles at millisecond time scales. Additionally, photocleavable vesicles demonstrated rapid release of molecular and macromolecular cargos. These results guided our design of multilamellar particles to photorelease surface-attached proteins, photoinduce cargo recruitment, and photoconvert vesicle morphology. Real-time characterization of the breakdown and reassembly of lamellar structures provides insights on partial cargo retention and informs the design of versatile, optically regulated carriers for applications in nanoscience and synthetic biology.