Interplay of long-chain tetrazine derivatives and biomembrane components at the air-water interface

Tetrazine (Tz) is an emerging bioorthogonal ligand that is expected to have applications (e.g., bioimaging) in chemistry and chemical biology. In this review, we highlight the interactions of reduced tetrazine (rTz) derivatives insoluble in aqueous media with biological membrane constituents or their related lipids, such as dipalmitoyl-phosphatidylcholine, dipalmitoyl-phosphatidylethanolamine, dipalmitoyl-phosphatidylglycerol, palmitoyl-sphingomyelin, and cholesterol in the Langmuir monolayer state at the air-water interface. The two-component interaction was thermodynamically elucidated by measuring the surface pressure (π) and molecular area (A) isotherms. The monolayer miscibility between the two components was analyzed using the excess Gibbs energy of mixing and two-dimensional phase diagram. The phase behavior of the binary monolayers was studied using the Brewster angle, fluorescence, and atomic force microscopy. This study discusses the affinities of the rTz moieties for the hydrophilic groups of the lipids used.