pH and Temperature Modulated Aggregation of Hydrophilic Gold Nanorods with Perylene Dyes and Carbon Nanotubes

Hydrophilic mercaptosuccinic acid (MSA) monolayer-protected gold nanorods (GNRs) were synthesized. The resulting GNRs encapsulated with biocompatible MSA molecules via covalent Au-S linkages were found to be able to self-aggregate through intermolecular hydrogen bonding. Interestingly, when the hybrid GNRs (MSA-GNR) were mixed with the hydrophilic fluorescent perylene diimide (PDI) molecules and carboxylic acid modified single-wall carbon nanotubes (CNT-COOH), respectively, their aggregation behaviors were pH- and temperature-dependent, which were investigated by UV-vis, fluorescence spectra, and TEM images. The aggregates of MSA-GNR with functional PDI and CNT-COOH were able to combine the properties of each component through noncovalent interactions, providing insight into developing new multifunctional metal nanocomposites with properties tailored for their practical application.