Paper PL-TuP8
Controlled Assembly of Asymmetrically Functionalized Gold Nanoparticles

Tuesday, October 16, 2007, 6:00 pm, Room 4C

Metal nanoparticles have received great attention due to their unique optical properties and wide range of applicability. In this context, programmable assembly of nanoparticles to control particle-particle interactions is a major challenge for the application of nanoparticles in device fabrication and detection systems. Different methods have been developed to achieve asymmetrically functionalized gold nanoparticles including the use of organic bridged ligands, oligonucleotides, and solid phase approaches to form gold nanoparticle dimer, trimer and tetramer assemblies. Of these architectures, dimers are of special interest because of their application as substrates in surface-enhanced Raman spectroscopy (SERS). In addition, one-dimensional nanoparticle chains show potential usefulness in fabrication of optoelectronic devices. We have developed a versatile solid phase synthesis of gold nanoparticle dimers using commercially available organic reagents through an asymmetric functionalization pathway. The method may be used to synthesize dimers for a wide size range of gold nanoparticles. In addition, we demonstrate the synthesis of dimers consisting of two particles with different sizes. The dimer yield varies from ~30% to ~65% depending on the nanoparticles’ size. The dimers demonstrate remarkable stability in ethanol without further processing. We have also developed a simple synthetic route to prepare one-dimensional gold nanoparticle chains using asymmetrically functionalized gold nanoparticles and poly(acrylic acid) via a simple amide couple reaction. The length of the synthesized nanoparticle chains varies from 256-400 nm with regular interparticle spacing (~2.7 nm). The synthesized chains display distinct optical properties compared to individual nanoparticles. This methodology also is applicable for gold nanoparticle with different sizes.