Stabilization of Supramolecular Membrane Protein-Lipid Bilayer Assemblies Through Immobilization in a Crystalline Exoskeleton

Abstract

<div> <div> <div> <p>Artificial native-like lipid bilayer systems constructed from phospholipids assembling into unilamel- lar liposomes allow the reconstitution of detergent-solubilized transmembrane proteins into supramolecular lipid-protein assemblies called proteoliposomes, which mimic cellular membranes. Stabilization of these com- plexes remains challenging because of their chemical composition, the hydrophobicity and structural instabil- ity of membrane proteins, and the lability of interactions between protein, detergent, and lipids within micelles and lipid bilayers. In this work we demonstrate that metastable lipid, protein-detergent, and protein-lipid su- pramolecular complexes can be successfully generated and immobilized within zeolitic-imidazole framework- 8 (ZIF-8) to enhance their stability against chemical and physical stressors. Upon immobilization in ZIF-8 bio- composites, blank liposomes, and model transmembrane metal transporters in detergent micelles or embed- ded in proteoliposomes resist elevated temperatures, exposure to chemical denaturants, aging, and mechanical stresses. Extensive morphological and functional characterization of the assemblies upon exfoliation reveal that all these complexes encapsulated within the framework maintain their native morphology, structure, and activity, which is otherwise lost rapidly without immobilization. </p> </div> </div> </div>

Biomaterials and nanomaterials for sustained release vaccine delivery

“…This study was interesting because they showed a more stable method to encapsulate antigens and demonstrated that the biomaterial could prime the immune system without the need of the adjuvant. A more recent development has shown that biomimetic coating of ZIFs on lipid nanoformulations promote their stability for many months in the mail (Herbert et al, 2021). This could have potential applications for stabilizing the newest lipid‐based vaccines.…”

“…This required cooling/cold‐chain makes the delivery of vaccines expensive, and the cost of keeping them cold can account for as much as 80% of the total cost of the immunization (Ashok, Brison, & LeTallec, 2017; Bogataj, Bogataj, & Vodopivec, 2005; Karishma, Donna, Timothy, & Neena, 2012; Setia et al, 2002; Welch et al, 2018). This instability has made controlled release strategies for delivery of LNP‐based vaccines difficult, though emerging approaches using metal–organic frameworks have shown considerable promise (Herbert et al, 2021). The ideal 21st‐century vaccine should be safe, patient‐friendly, and stable enough such that it can be stored at ambient conditions and provide long‐term immunity after one administration.…”

Metal-Organic Framework Encapsulated Whole-Cell Vaccines Enhance Humoral Immunity against Bacterial Infection

“…Biomimetic mineralization with ZIF is extremely gentle and we have previously shown that membrane bound proteins are not only preserved but protected by ZIF encapsulation in lipid nanoparticles. 73 To show that our ZIF encapsulation approach preserves natively folded proteins better than traditional methods of inactivation, we conducted an agglutination assay using yeast. The fimbriae on the surface of CFT073 contain glycoproteins that are highly specific binders of sugar.…”

“…Biomimetic mineralization with ZIF is extremely gentle and is known to not alter the conformation of membrane bound proteins. 69 We tested whether ZIF encapsulation inactivates CFT073. Following formation of the ZIF shell, immobilized CFT073 was incubated for 30 min at room temperature and exfoliated with 500 mM sodium acetate buffer.…”

“…To address this challenge, we developed biomimetic encapsulation [61][62] methods that fully encase individual bacteria inside a crystalline polymeric matrix called Zeolitic Imidazolate Frameworks (ZIFs -Scheme 1). 63 We and others showed that mixing an array of biological molecules, including fluorescent proteins, 64 insulin, 65 proteins, [66][67] IgG, 68 viral nanoparticles, 37,[69][70] RNA, yeast, [71][72] proteoliposomes, 73 and Gram-positive andnegative bacteria 74 within the ZIFs framework, incarcerates the target in a biodegradable matrix. ZIFs are a subclass of a broader family of solid-state single crystal metal organic frameworks (MOFs) characterized by interconnected organic ligands linked by metal nodes extending infinitely in all directions (Scheme 1A and 1B).…”