Pablo Rojas Martinez

/images/ESRs photos/ESR10.png   Self-assembly of Molecular-based Nanowires

   Newcastle University

      DNA is a biopolymer with capacity of store and transfer genetic information in a sequence of four monomers, called nucleobases. This behaviour is based in a recognition between nucleobase pairs adenine-thymine and guanine-cytosine through the formation of specific hydrogen bond. In addition to their biological importance this class of molecules are now finding use in new nanostructured materials. Specifically, their use in developing of nanoscale materials and technologies arises from the size, morphology and the self-assembling properties that allows bottom-up fabrication with nanometric precision through programming of sequence. This has now been refined to allow the construction of exquisitely complex two and three dimensional nanostructured architectures using ‘’DNA origami’’.

However, for some applications the components of DNA lack suitable electronic properties. To address this-in the last decade studies have been carried out to modify or integrate DNA with other types of materials. One approach involves replacing hydrogen bonding for coordination bonding. In this way metal ions can be included to DNA structures thus equipping them with new electronic, magnetic, optic properties, etc. Of particular interest in this project is the introduction of novel opto-electronic properties into DNA-based materials.

The main aim of this project is the preparation and characterization of coordination polymers based on modified nucleobase derivatives. The focus will be on the use of noble metals, -such Cu, Ag, Au, with the aim of preparing coordination polymers using nucleobases as bridging ligands (Figure 1) as nanowire materials. Studies will then be aimed at integrating these types of coordination motif into DNA structures. 

 /images/ESRs project pics/UNEW fig.png

Figure 1. Thiolate polymer where R- could be DNA chains

The materials will be characterised using a range of techniques such as scanning probe microscopy, UV-vis and fluorescence spectroscopy, X-ray diffraction, etc. in order to determine the structural and compositional features.

Other aims in the project will be the electrical characterisation of coordination polymer and evaluation of their suitability for sensing application. Electrical characterisation of the coordination polymer will carried out by current-voltage-temperature to achieve an understanding of the charge transport mechanism. Finally we will design a prototype nanowire-based gas sensor incorporating the polymers into devices and testing the response of their electrical properties to gaseous analytes