It is demonstrated with two types of gold nanoparticles how manipulating charge and functionality of the ligand shell can be used to dramatically change their dispersibility in different media. In the case of crown-ether modified particles, the complexation of the crown can make the particles more hydrophobic and can be used to phase extract them, for example, from water into chloroform. Mercaptocarborane-capped gold particles, on the other hand, can be highly charged by storing monovalent cations in the ligand shell and electrons in the metal core. Charged particles disperse readily in water, whereas removal of the charge makes them readily dispersible in diethylether and toluene. Both types of particles discussed here can transport cations and electrons, and it is our aim to anchor them for this purpose inside biological membranes by manipulating their dispersibility in water. This requires ballancing interactions carefully, since in most cases the particles prefer to either surround themselves with other particles and flocculate, or to reside at interfaces. Flocculation here is an entropically driven process, which can be avoided by lowering the temperature. I wlll show electron microscopic evidence of controlled association of particles with phospholipid membranes of vesicles as well as fluorescence spectroscopic and electrochemical evidence of charge transfer across the membrane, mediated by the gold nanoparticles. Shuttle versus channel mechanisms will be considered for both types of particles, and the possibility of electron transfer using the particle as a metallic nanowire will be discussed.

Directing gold nanoparticles into biological membranes by fine tuning their dispersibility

255th National Meeting (2018)

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