Research

General Research Themes

1. Photophysical Studies of DNA: to trigger and monitor nucleic acid processes in complex systems through light activation
2. Fundamental and applied studies of micro- and nanomaterials

1. Photophysical Studies of DNA

This work aims to develop a comprehensive picture of the photostabilty of DNA to enhance our understanding of the processes leading to photodamage.

(i) Spectroscopic Study of Excited States of Nucleic acid Systems to Unravel the Ultrafast Dynamics of DNA:

This research conducted in collaboration with the Central Lasers Facility in the Rutherford Appleton Laboratory with the team of Prof. Mike Towrie.

The process of light absorption by DNA results in reactive species which may lead to DNA damage and mutagenic products. We consider how DNA copes with absorbed photons and the factors that influence the lifetime and deactivation of the excited states of DNA upon 'direct exctiation of UV light. We are interested to learn the role of sequence and structure on these events and of particular interest is non-canonical G-quadruplex and i-motif DNA. To do this we employ steady state, to provide structural characterisation, and ultrafast electronic and vibrational spectroscopy to profile events on the fs to ns timescale.

(ii) Use of molecular probes and nanoparticles to image, report and trigger DNA function

We also are interested in 'sensitised processes' caused by energy or electron transfer from photoactivated molecules and nanomaterials bound to DNA. This is challenging due to the variety of possible binding sites. One approach to this is to investigate the excited state processes in crystal samples where the exact location of DNA bases and any bound molecules are known have been published in Nature Chemistry. This work was in collaboration with Prof. John Kelly in TCD and Prof Christine Cardin in the University of Reading. In addition, to activating DNA damage, small molecules and nanoparticles can also be used to visualise and resolve cellular processes. We are also interested in exploiting the sensitivity of photoactive probes to report on the binding environment. Again of particular interest is the interaction and preferential binding to particular structures of DNA.

2. Fundamental and applied studies of micro- and nanomaterials

Carbon based Nanomaterials: Photophysics, binding interactions & cellular uptake

Carbon nanomaterials constitute a fascinating family of functional materials with potential application across a range of areas. We are interested in undertanding their inherent photophysical properties and also how they interact with the surrounding molecular world, especially with biological molecules.

(i) Carbon nanodots (C-dots) are a relatively new member of this family that comprise discrete, quasi-spherical nanoparticles with sizes below 10 nm. In general, C-dots display size and excitation wavelength (λex) dependent photoluminescence (PL) behaviour. C-dots are attractive due to their chemical inertness and likely lower toxicity. We are currently exploring the influence of surface chemistry on the photophysical behaviour of these particles and are particularly interested in how they bind to biological molecules and behave in cells. We employ a variety of techniques to prepare and purify the particles and exploit carbon chemistry to functionalise the surface. Our current investigation of the uptake of these particles by Badriah hifni is in collaboration with Prof Jeremy Simpson in the School of Biology and Environmental Science at UCD.

The photophysical properties of C-dots were recently successfully translated to carbon fibers by Clara Deeney, using a microwave templated synthesis approach.

(ii) Carbon nanohorns are larger nanoparticles 80-100 nm in diameter, which are formed from clusters of nanohorns. The biodegradibility of these materials serves as a potential for biocompatible delivery agents. Current work in the group explores the ability to tune their surface functionalisation. The materials are inherently non-luminescent but modification with fluorescent molecules allows detection in cells. A recent study by Stephen Devereux in collaboration with Prof. Donal O'Shea (RCSI) has revealed the importance of surface modification on the effective uptake of carbon nanohorns whose emission was only detected when the nanoparticles entered the cells.