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Clusters of Nanoscale Liposomes Modulate the Release of Encapsulated Species and Mimic the Compartmentalization Intrinsic in Cell Structures



Igor Kevin Mkam Tsengam, Marzhana Omarova, Lauren Shepherd, Nicholas Sandoval, Jibao He, Elizabeth G. Kelley, Vijay John


We report the ability to place a high concentration of liposomes in a confined volume as a multicompartment cluster that mimics biological cells and allows for the modulation of release of encapsulated species. The formation of these coated multicompartmental structures is achieved by first binding liposomes into clusters before encapsulating them within a two-dimensional metal organic framework composed of tannic acid coordinated with a metal ion. The essential feature is a molecularly thin skin over a system of clustered liposomes. The structural features of these pouches are revealed by small angle scattering and electron microscopy. Through cryogenic electron microscopy, clusters with intact liposomes are observed that appear to be encapsulated within a pouch. Small angle X-ray scattering shows the emergence of a relatively weak Bragg peak at q = 0.125{angstrom}-1, possibly indicating the attachment of the bilayers of adjacent liposomes. The metal phenolic network (MPN) coating on the liposome clusters results in a reduced release rate of the encapsulated rhodamine B dye. We further show the possibility of communication between adjacent liposomal compartments by demonstrating enhanced energy transfer using Fluorescence Resonance Energy Transfer (FRET) experiments where the lipophilic donor dye 3,3'-dioctadecyloxacarbocyanine perchlorate (DiO) incorporated within one compartment transfers energy upon excitation to the lipophilic acceptor dye 1,1'-dioctadecyl-3,3,3',3'- tetramethylindocarbocyanine perchlorate (DiI) in a neighboring compartment due to their close proximity within the multicompartmental cluster. These observations have significance in adapting these multicompartmental structures that mimic biological cells for cascade reactions and as new depot drug delivery systems.
ACS Applied Nano Materials


liposomes, metal organic framework, compartmentalization, small angle scattering
Created October 23, 2019, Updated December 20, 2019