Clustering of Giant Unilamellar Vesicles Promoted by Covalent and Noncovalent Bonding of Functional Groups at Membrane-Embedded Peptides.

Access to clusters of cell-sized globular objects such as giant unilamellar vesicles (GUVs) is of increasing interest due to their potential applications in prototissue and cell-cell adhesion studies. Aggregations of GUVs by four different approaches were observed via covalent as well as noncovalent bond participations of functional groups at membrane embedded cholesterylpeptides using optical microscopy. Passive air oxidation of GUV-surface thiols into trans-GUV disulfide bonds promoted multivesicle aggregation. Aggregations of GUVs into multiclusters were also achieved by introduction of bispyridyl-ligand substituted peptides into GUV-membranes succeeded by rhodium diacetate mediated vesicle clustering and, furthermore, by coinstalling a biotin moiety streptavidin addition attenuating the clustering effect visualized by formation of compact superaggregated GUV-multiclusters. Contacting between two different GUV-populations, i.e., GUV-heteroconnection, was achieved by trans-GUV phenyl ester-hydrazine ligations producing GUV-heteroclusters. Indirectly, GUV-clustering was achieved by strain-promoted azide-alkyne cycloaddition (SPAAC) reacting bicyclononyne (BCN)-GUVs with azido-GlcNAc succeeded by biotinylated wheat germ agglutinin (WGA)-lectin/streptavidin incubation arousing cross-binding of GUVs.