Contact
    Start Publications Interplay of Hydrophobic and Electrostatic Interactions between ...
    ←  Publication Finder
    KSV NIMA

    Interplay of Hydrophobic and Electrostatic Interactions between Polyoxometalates and Lipid Molecules

    Year: 2017

    Journal: J. Phys. Chem. C, Volume 121, JUN 15, page 12895–12902

    Authors: Kobayashi, Daiki; Nakahara, Hiromichi; Shibata, Osamu; Unoura, Kei; Nabika, Hideki

    Organizations: Nippon Sheet Glass Foundation for Materials Science and Engineering; JSPS KAKENHI [16H04092, 26600021]

    The Hofmeister series has long been of both scientific and technological importance because it allows systematic predictions of the interaction between ions and molecules to be made. In this work, three different polyoxometalate (POM) anions and three different lipid monolayers were used to investigate the interplay between electrostatic and hydrophobic interactions. We used three Keggin-type POMs with different charges ([PW12O40](3-), [SiW12O40](4-), and [H2W12O40](6-)) to eliminate any effects of morphology and to focus on the effects of the charge and hydrophobicity of the POM anions. The POMs adsorb onto cationic lipid monolayers via electrostatic interactions, while hydrophobic interaction is the dominant factor for adsorption onto anionic lipid monolayers when charge neutralization is provided by cationic counterions. In contrast, the dominant interactions experienced by zwitterionic lipid monolayers can switch between electrostatic interactions for POMs with higher charge density and hydrophobic interactions for POMs with lower charge density. Furthermore, the dominant interaction could also switch as a function of lipid density. In the gas phase, lipid monolayers mostly interact with POMs through electrostatic interactions, and the strength of the influence of the POM varies in the order [PW12O40](3-) < [SiW12O40](4-) < [H2W12O40](6-). In contrast, the order switches to [PW12O40](3-) > [SiW12O40](4-) > [H2W12O40](6-) when the POM interacts with a compressed lipid monolayer (surface pressure = 40 mN/m), which reflects the Hofmeister series and the chaotropic nature of the POMs. Thus, hydrophobic interactions govern the penetration of the lipid monolayer for condensed cell membranes irrespective of the charge of the lipid. The observed switch implies the importance of the interplay between the electrostatic and hydrophobic interactions. Our findings provide new insight into the switchable binding modes of POMs for cell membranes with different lipid composition, density, and hydrophobicity, enabling the design of tailor-made POM-based materials for a new generation of antimicrobial agents.
    View publication