Nanomechanics of Anion−π Interaction in Aqueous Solution

Abstract

Noncovalent interactions play a constitutive role in numerous biological processes, including biomolecular adhesion, recognition, and transport. Unlike π−π and cation−π interactions, anion−π interaction was only recently and computationally recognized to participate in biomolecular science. Here, we present the first experimental identification and direct quantification of the nanomechanics of anion−π interaction in aqueous solution by using a surface forces apparatus with complementary computational simulations. Anionic phosphate ester and π-conjugated catecholic moieties that abound in marine bioadhesives were used as the model system. Robust adhesion was observed and attributed to anion−π interaction, which was found to be enabled by the cooperative cation−π interaction due to the coexistence of a cation. The anion−π interaction strength follows the trend phosphate ester > HPO 4 2− > SO 4 2− > NO 3 − , affected by charge density, polarity, and hydration effect.

Ultra-strong bio-glue from genetically engineered polypeptides

“…The normal force-distance profiles and adhesion forces between two components (namely cationic polypeptide and anionic surfactant) that form the bio-glue were determined using an SFA. The typical experimental setup and working principle of SFA have been reported previously 45 – 48 . Briefly, thin back-silvered mica sheets (thickness 1–5 μm) were first glued onto cylindrical silica disks (radius R = 2 cm).…”

Anion–π interaction at the solid/water interfaces

“…This is a remarkable result of direct observation of anion-p interactions with the force measurement, as reported by Zeng. 22 The effect of anion species on the inhibition was examined using 10 mM TBACl, TBABr, and TBAI in water (Fig. 5b-d).…”

“…17,18 Furthermore, Zeng et al revealed that anion-p and cation-p interactions coexist during bioadhesion based on catecholic moieties with phosphate ester and potassium. 19 These reports reveal that anion-p interaction is an excellent tool to control not only small molecular functions but also macromolecular and macroscale phenomena at the material interfaces.…”

“…21 As mentioned above, anion-p interactions were also found to contribute to the biological adhesion process (SFA measurements). 22 Inhibition experiments with these anions have revealed that the strength of anion-p interactions follows the order HPO 4…”

Azacalix[3]triazines: A Substructure of Triazine‐Based Graphitic Carbon Nitride Featuring Anion‐π Interactions

“…Zuschriften 16516 www.angewandte.de negatively charged. [18] Furthermore, Fujita et al, reported efficient guest capture in crystal sponges with electrondeficient triazine as their frameworks. [19] Hence, it is clear that anion-p interactions can be utilized for the selection of substrates for the photocatalytic reactions of GCNs and could further expand the scope and possibility of GCNs as photocatalysts.…”