This report describes the use of surface plasmon spectroscopy to study the effect of surface wettability on the nonspecific adsorption of proteins and detergents to self-assembled monolayers (SAMs) of alkanethiolates on gold. The adsorption of both proteins and detergents to uncharged SAMs showed a general dependence on the wettability of the surface as determined by the contact angle of water on the SAM under cyclooctane (θco). The effect of the wettability of the SAMs on the adsorption of sodium dodecyl sulfate (SDS) was dependent on whether micelles were present. Above the critical micelle concentration (cmc), SDS adsorbed only on surfaces that gave contact angles with values of cos θco < 0 (i.e., the transfer of the surface from water to cyclooctane has a favorable free energy). Below the cmc, the requirement for adsorption was much more stringent:  SDS adsorbed only on the surfaces that gave values of cos θco < −0.9. Similarly, the effect of the wettability of the SAMs on the adsorption of proteins showed a dependence on the size of the proteins. The smaller proteins tested (ribonuclease A and lysozyme) adsorbed only on the least wettable surfaces tested (cos θco < −0.83). The larger proteins tested (pyruvate kinase, fibrinogen, and γ-globulin) also adsorbed best to the least wettable surfaces, but adsorbed to some extent on almost all the surfaces; the single exception was a SAM presenting hexa(ethylene glycol) groups at the surface, to which no protein adsorbed. Films of adsorbed proteins were desorbed from the SAMs by treatment with detergent.

This paper reports the generation of a self-assembled monolayer (SAM) that selectively binds proteins whose primary sequence terminates with a His-tag: a stretch of six histidines commonly incorporated in recombinant proteins to simplify purification. The SAM was prepared by the adsorption onto a gold surface of a mixture of two alkanethiols: one thiol that terminated with a nitrilotriacetic acid (NTA) group, a group that forms a tetravalent chelate with Ni(II), and a second thiol that terminated with a tri(ethylene glycol) group, a group that resists protein adsorption. His-tagged proteins bound to the SAM by interaction of the histidines with the two vacant sites on Ni(II) ions chelated to the surface NTA groups. Studies with model proteins showed the binding was specific for His-tagged proteins and required the presence of Ni(II) on the surface. Immobilized His-tagged proteins were kinetically stable in buffered saline at pH 7.2 but could be desorbed by treatment with 200 mM imidazole. Surface plasmon resonance studies for two model systems showed that His-tagged proteins adsorbed on the NTA-SAM retained a greater ability to participate in binding interactions with proteins in solution than protein immobilized in a thin dextran gel layer by covalent coupling.

During the SARS-CoV-2 pandemic, novel and traditional vaccine strategies have been deployed globally. We investigated whether antibodies stimulated by mRNA vaccination (BNT162b2), including 3 rd dose boosting, differ from those generated by infection or adenoviral (ChAdOx1-S and Gam-COVID-Vac) or inactivated viral (BBIBP-CorV) vaccines. We analyzed human lymph nodes after infection or mRNA vaccination for correlates of serological differences. Antibody breadth against viral variants is less after infection compared to all vaccines evaluated, but improves over several months. Viral variant infection elicits variant-specific antibodies, but prior mRNA vaccination imprints serological responses toward Wuhan-Hu-1 rather than variant antigens. In contrast to disrupted germinal centers (GCs) in lymph nodes during infection, mRNA vaccination stimulates robust GCs containing vaccine mRNA and spike antigen up to 8 weeks post-vaccination in some cases. SARS-CoV-2 antibody specificity, breadth and maturation are affected by imprinting from exposure history, and distinct histological and antigenic contexts in infection compared to vaccination.

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An ELISA assay is described for measuring the binding of influenza virus A-X31 to α-sialoside groups that are linked to biotin-labeled polyacrylamides. The efficacy of these polymers in inhibiting the adhesion of influenza virus to erythrocytes (as measured by a hemagglutination assay) was shown to be directly related to the binding affinity of the polymers for the viral surface:  the differences in inhibitory efficacy among the polymeric inhibitors and monomeric α-methyl sialoside, among fractions of a polymeric, polyvalent inhibitor with narrow molecular weight ranges, and among polymeric inhibitors prepared by copolymerization or modification of a preformed polymer chain, all correlated with differences in the affinity of the inhibitors for the surface of the virus. The polymeric inhibitors studied had affinities for the viral surface that ranged between 103 and >106 greater than α-methyl sialoside, on the basis of total sialic acid groups in solution. The role of steric stabilization in the mechanism by which these polymers inhibit hemagglutination was investigated. The ability of the polymeric, polyvalent inhibitors to inhibit the binding of a polyclonal antibody to the viral surface suggests that steric stabilization may also be an important effect in this system.