Summary:

Aptamers are single-stranded oligonucleotide sequences that exhibit high affinity and high specificity binding for nonnucleotide targets.

Using a procedure called "systematic evolution of ligands by exponential enrichment" (SELEX), aptamers can be identified from combinatorial libraries consisting of ~ 1012-1015 random sequences. This in vitro selection procedure has led to the discovery of aptamers for a variety of targets including but not limited to ions, small macromolecules, and whole cells. Due to their small molecular weight, ease of processing, and long-term stability, aptamers are now increasingly explored as potential alternatives to antibodies as high affinity ligands. These characteristics highlight the potential impact of aptamers in areas such as biosensing, diagnostics, and therapeutics.

Gold nanoparticles have been widely studied for various diagnostic, imaging and therapeutic applications due to their shape and size-dependent optical properties. Tight control over the size distribution and shape of gold nanoparticles using conventional solution precipitation approaches, however, is challenging.  In addition, subsequent assembly of nanoparticles into well-organized spatial patterns on substrates can pose additional challenges. The overall goal of the proposed research is to identify aptamer sequences from a random library that bind both to gold nanoparticles and to gold ions.  If successful, this approach to aptamer screening will potentially allow for the simultaneous precipitation and patterning of homogeneous, spherical gold nanoparticles.