Irene Piscopo’s research while affiliated with University of Victoria and other places

Gold nanoparticles (AuNPs) have been exploited for a wide range of potential applications, including drug delivery systems, catalysts, optical sensors and antimicrobial agents [1-5]. However, the harsh conditions employed in several synthetic approaches has forced researchers to investigate milder routes [6]. Biological macromolecules such as proteins [7], viruses [8], and plasmid DNA [9] have been shown to be successful candidates to ensure a milder pathway in the formation of AuNPs. Many of the aforementioned methodologies employing biological precursors nevertheless present other drawbacks such as lack of size tunability, broad dispersity, and poor shape control partially due to the tendency of cationic gold to disproportionate in aqueous solutions [10], as well as the difficulties in stabilizing metallic NPs. Combining plasmid DNA as a biomolecular reactor with a kinetically based approach, we have been able to stabilize and control the size of AuNPs.

Metallic and non-metallic nanoparticles (NPs), ranging in size from 1–200 nm, have unique functional properties that differ from their bulk materials and their component atoms or molecules. These unique properties have driven the demand for nano-sized materials and new methods to synthesize NPs, which are used in drug delivery systems, bio-imaging agents, catalysts, photonics, and optical devices. Inorganic NPs can be synthesized with a variety of methods that impart size, shape, and other structural properties. Cobalt-based NPs, for instance, display unique size and shape-dependent magnetic properties, while the band gap, UV blocking properties and stability of zinc oxide (ZnO) NPs enable new applications in products ranging from cosmetics to solar cell power.

A new method for synthesizing gold, nickel, and cobalt metal nanoparticles at room temperature from metal salts employing plasmid DNA in a toroidal topology as a sacrificial mold is presented. The diameter of the toroidal DNA drives the formation and size of the nanoparticle, and UV light initiates the oxidation of the DNA and concomitant reduction of the DNA bound metal ions. The nanoparticles were characterized by atomic force microscopy (AFM), transmission electron microscopy (TEM), and electron diffraction (ED).