Understanding the interactions of non-ionizing radiation with living organisms has been the focus of much research over recent decades. The complex nature of these interactions warrants development of theoretical and experimental studies to gain an insight into predicting and monitoring the success of photodynamic therapy (PDT) protocols. There is a major impetus towards evidence-based recommendations for patient diagnosis, treatment and management. Knowledge of the biophysical aspects of PDT is important for improving dosimetry protocols. Fluorescence in clinical PDT may be used to detect and diagnose pre-malignant and malignant conditions, while photobleaching can monitor changes in fluorescence during treatment. Combining empirical fluorescence photobleaching clinical data with computational modelling enables clinical PDT dosimetry protocols to be investigated with a view to optimising treatment regimes. We will discuss how Monte Carlo radiation transfer (MCRT) modelling has been intercalated in the field of fluorescence detection and PDT. In this paper we highlight important aspects of basic research in PDT by reporting on the current utilisation of fluorescence in clinical PDT from both a clinical and theoretical perspective. Understanding and knowledge of light propagation in biological tissue from these perspectives should have a positive impact on treatment planning.

The study of mitochondria and mitochondrial Ca2+ signalling in localised regions is hampered by the lack of tools that can uncouple the mitochondrial membrane potential (DeltaPsi(m)) in a spatially predefined manner. Although there are a number of existing mitochondrial uncouplers, these compounds are necessarily membrane permeant and therefore exert their actions in a spatially unselective manner. Herein, we report the synthesis of the first caged (photolabile protected) mitochondrial uncouplers, based on the tyrphostin AG10. We have analysed the laser photolysis of these compounds, using (1)H NMR and HPLC, and demonstrate that the major product of caged AG10 photolysis is AG10. It is shown that photolysis within single smooth muscle cells causes a collapse of DeltaPsi(m) consistent with photorelease of AG10. Furthermore, the effect of the photoreleased AG10 is localised to a subcellular region proximal to the site of photolysis, demonstrating for the first time spatially predefined mitochondrial uncoupling.

The synthesis of a range of caged TRPV1 agonists and antagonists is reported. The photolysis characteristics of these compounds, when irradiated with a 355 nm laser, have been studied and in all cases the desired compound was produced. Photolysis of a caged TRPV1 agonist in cultured trigeminal neurons produced responses that were consistent with the activation of TRPV1 receptors.

An attractive approach to target intracellular macromolecular interfaces is to design small high affinity proteins. In this manuscript a stable, autonomous, human derived non-immunogenic, disulphide-free VH domain, has been engineered for intracellular expression studies. VH domains can be designed to possess a large dynamic repertoire of binders, as opposed to other scaffolds types that are highly rigid and possess fewer sites of random variation. Picomolar inhibitors were identified using phage display against the eIF4F complex, which is commonly hyper-activated in many cancers. These molecules were also shown to impair cellular proliferation and to reduce the expression of malignancy related proteins. Structural characterization elucidated that these VH domains bound eIF4E at the eIF4G interaction interface via a novel binding pose. Molecules able to mimic this pose and interfere with the eIF4F complex are potentially important for wide-ranging tumour therapy applications.

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