Supramolecular Control over the Interparticle Distance in Gold Nanoparticle Arrays by Cyclodextrin Polyrotaxanes

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Coelho, Joao Paulo and Osío Barcina, José de Jesús and Junquera González, Elena and Aicart Sospedra, Emilio and Tardajos Rodríguez, Gloria and Gómez Graña, Sergio and Cruz Gil, Pablo and Salgado, Cástor and Díaz Núñez, Pablo and Peña Rodríguez, Ovidio and Guerrero Martínez, Andrés (2018) Supramolecular Control over the Interparticle Distance in Gold Nanoparticle Arrays by Cyclodextrin Polyrotaxanes. Nanomaterials, 8 (3). p. 168. ISSN 2079-4991

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Official URL: https://doi.org/10.3390/nano8030168




Abstract

Amphiphilic nonionic ligands, synthesized with a fixed hydrophobic moiety formed by a thiolated alkyl chain and an aromatic ring, and with a hydrophilic tail composed of a variable number of oxyethylene units, were used to functionalize spherical gold nanoparticles (AuNPs) in water. Steady-state and time-resolved fluorescence measurements of the AuNPs in the presence of α-cyclodextrin (α-CD) revealed the formation of supramolecular complexes between the ligand and macrocycle at the surface of the nanocrystals. The addition of α-CD induced the formation of inclusion complexes with a high apparent binding constant that decreased with the increasing oxyethylene chain length. The formation of polyrotaxanes at the surface of AuNPs, in which many α-CDs are trapped as hosts on the long and linear ligands, was demonstrated by the formation of large and homogeneous arrays of self-assembled AuNPs with hexagonal close packing, where the interparticle distance increased with the length of the oxyethylene chain. The estimated number of α-CDs per polyrotaxane suggests a high rigidization of the ligand upon complexation, allowing for nearly perfect control of the interparticle distance in the arrays. This degree of supramolecular control was extended to arrays formed by AuNPs stabilized with polyethylene glycol and even to binary arrays. Electromagnetic simulations showed that the enhancement and distribution of the electric field can be finely controlled in these plasmonic arrays.


Item Type:Article
Uncontrolled Keywords:supramolecular chemistry; self-assembly; gold nanoparticle; cyclodextrin; polyrotaxane; array; hot spot; surface-enhanced spectroscopy
Subjects:Medical sciences > Pharmacy > Pharmaceutical chemistry
Medical sciences > Pharmacy > Organic chemistry
ID Code:69369
Deposited On:22 Dec 2021 10:32
Last Modified:22 Dec 2021 11:11

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