Quantification of the multivalent interactions of influenza viruses binding at interfaces may provide ways to tackle key biological questions regarding influenza virulence and zoonoses. Yet, the deconvolution of the contributions of molecular and interfacial parameters, such as valency, interaction area, and receptor density, to the binding of whole viruses is hindered by difficulties in the direct determination of these parameters. We report here a chemical platform technology to study the binding of multivalent recombinant hemagglutinin (rHA) nanoparticles at artificial sialoglycan cell receptor-presenting interfaces in which all these parameters can be derived, thus allowing the desired full and quantitative binding analysis. SiO 2 substrates were functionalized with supported lipid bilayers containing a targeted and tunable fraction of a biotinylated lipid, followed by the adsorption of streptavidin and biotinylated polyvalent 2,3- or 2,6-sialyl lactosamine (SLN). rHA nanoparticles were used as a virus mimic to provide a good prediction of the number of interactions involved in binding. Low nanomolar affinities and selectivities for binding at the 2,6-SLN platforms were observed for rHA particles from three different virus variants. When fitting the data to a multivalency model, the nanomolar overall affinity appears to be achieved by 6–9 HA–sugar molecular interaction pairs, which individually present a rapid association/dissociation behavior. This dynamic behavior may be an essential biological attribute in the functioning of the influenza virus.

Protein immobilization on surfaces, and on lipid bilayerss pecifically,h as great potential in biomoleculara nd biotechnological research. Of current special interest is the immobilizationo fp roteins using supramolecular noncovalent interactions. This allows for ar eversible immobilization and obviates the use of harsh ligation conditions that could denature fragile proteins.I nt he work presented here, reversible supramolecular immobilization of proteins on lipid bilayer surfaces was achieved by using the host-guest interaction of the macrocyclic molecule cucurbit[8]uril. Af luorescent protein was successfully immobilized on the lipid bilayer by making use of the property of cucurbit [8]uril to host together am ethylviologen and the indole of at ryptophan positionedo nthe N-terminal of the protein. The supramolecular complex was anchored to the bilayer through ac holesterol moiety that was attached to the methylviologen tethered with asmall polyethylene glycolspacer.Protein immobilization studies using aq uartz crystal microbalance (QCM)s howedt he assembly of the supramolecular complexeso nt he bilayer. Specific immobilization through the protein N-terminus is more efficient than through protein side-chain events. Reversible surfacer eleaseo ft he proteins could be achieved by washing with cucurbit[8]uril or buffer alone.T he described system shows the potentialo fs upramolecular assembly of proteins and providesamethod for site-specific protein immobilization under mild conditions in ar eversible manner.

Multiple naphthol ligands were installed on the glycocalyx of white blood cells via metabolic labeling and subsequent strain promoted azide-alkyne cycloaddition. Only when cucurbit[8]uril was present to drive the formation of ternary complexes, cells specifically assembled on a methylviologen functionalized supported lipid bilayer through multivalent interactions.

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