Controlled assembly of protein-protected gold nanoparticles on noncovalent functionalized carbon nanotubes

We investigated the noncovalent functionalization of multi-walled carbon nanotubes (MWCNTs) by an aromatic chemical, 1-pyrenebutyric acid N-hydroxysuccinimide ester (PANHS), and produced four protein- (fibrinogen, gamma-globulin, hemoglobin, and fibronectin) protected gold nanoparticles (AuNPs) by a simple strategy. The formation of protein-protected AuNPs was evidenced by UV-vis spectra, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM), the successful chemical modification of MWCNTs with PANHS was identified by XPS and Raman spectra, and the MWCNT-AuNP hybrids were observed by TEM. We concluded that proteins can mediate the assembly of protein-protected AuNPs on PANHS-functionalized MWCNTs. Proteins, as an intermediate that can react with both MWCNTs and AuNPs, play a significant role for mediating the formation of different hybrids based on MWCNTs. This work provides a simple and potent strategy to prepare CNT-NP hybrids by using the interaction between CNTs and biomacromolecules, and on the other hand provides a potential application of protein-protected metallic NPs for preparing novel nanomaterials. (C) 2009 Elsevier Ltd. All rights reserved.