Hydrophobic Uptake, Transport and Release Using Gold Nanoparticle Supraspheres

Offer Zeiri, Analytical Chemistry, NRCN, Beer Sheva, Israel
Yizhan Wang, Chemistry, Ben Gurion University, Beer Sheva, Israel
Manoj Raula, Chemistry, Ben Gurion University, Beer Sheva, Israel
Benjamin Le, Institute Of Materials, École Polytechnique Fédérale De Lausanne , Lausanne, Switzerland
Francesco Stellacci, Institute Of Materials, École Polytechnique Fédérale De Lausanne , Lausanne, Switzerland
Ira A. Weinstock, Chemistry, Ben Gurion University, Beer Sheva, Israel

Controlled hydrophobically driven assembly of 4 nm gold nanoparticles in water was used to construct 200 nm supraspheres. Each of the water soluble supraspheres contains hydrophobic cavities between the estimated 27,400 nanoparticle building blocks, connected to each other by nanometer-sized pores. This gives a percolated network of hydrophobic cavities that can effectively absorb large numbers of organic molecules. After guest uptake, the supraspheres can be easily separated from the solution using centrifugation, and transferred to an organic solution wherein they disassemble, releasing the organic molecules.

Each suprasphere can absorb over two million organic guests, exceeding by five orders of magnitude the capacities of individual supramolecular cages or containers and rivalling those of zeolites and metal–organic frameworks on a mass-per-volume basis. In addition, the supraspheres also allow for chemoselectivity. Modification of the supraspheres capping ligands can control the guest uptake kinetic barrier, enabling specific molecule absorption.

Possible applications include uses as a chemoselective method for concentration, separation and analysis of target substances (such as explosives and toxic materials), as well as protected storage for light sensitive materials.