Porphyrin-DNA as scaffold for nanoarchitecture and nanotechnology

Nguyen, ThaoNguyen (2010) Porphyrin-DNA as scaffold for nanoarchitecture and nanotechnology. University of Southampton, School of Chemistry, Doctoral Thesis, 251pp.

Abstract

Porphyrins, a substance class that can be found in diverse materials including green leaves and red blood cells, have been studied extensively over many years due to their potential industrial applications, e.g. in making optical electronic devices, in artificial photosynthesis or in sensors. In contrast, DNA has only recently been found to be a good scaffold for the construction of functional molecules. Combining the chemical properties of porphyrins and DNA could open the door to the production of multiporphyrin arrays using DNA as a scaffold; such materials could have multiple applications, an example being molecular electronic devices.

The work described in this thesis reports on further investigations of the synthesis of the porphyrin?nucleotide and its incorporation into DNA sequences, in order to study the structural, chemical and electronic properties of the porphyrin?modified DNA. The analytical results, obtained from employing a variety of techniques such as UV?vis and fluorescence spectroscopy, UV?vis and fluorescence melting studies, circular dichroism spectroscopy and EPR (electron paramagnetic resonance) spectroscopy showed electronic interaction between porphyrins stacked on DNA. Metallation with zinc or copper of different porphyrins (namely diphenyl porphyrins and tetraphenyl porphyrins) was also successfully achieved, after they had been attached onto DNA. Based on EPR measurements, evidence was found for intermolecular stacking of the porphyrin?DNA which leads to self?assembled higher order structures. The EPR investigation also demonstrated that different oxidation states of metals held inside porphyrin?DNA could be monitored. Using CD spectroscopy based on a synchrotron light source, the first measurements were made of DNA in the far UV region (< 200 nm). All the results obtained in this work and elsewhere during the past few years show that DNA based materials are highly promising for future applications in many areas of science, but especially in electronics and health care.

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