Dataset to manuscript submitted to Theranostics, entitled: Local monitoring of photosensitizer transient states – feedback for enhanced efficiency and targeting selectivity in photodynamic therapy.

<strong>This folder contains all raw data underlying the results presented in a manuscript, submitted to Theranostics, and entitled:</strong> <strong>Local monitoring of photosensitizer transient states – feedback for enhanced efficiency and targeting selectivity in photodynamic therapy.</strong> <strong>Authored by:</strong> Elin Sandberg ¹, Chinmaya V Srambickal ¹, Joachim Piguet ¹, Haichun Liu ¹ and Jerker Widengren ^1,* ¹ Experimental Biomolecular Physics, Department of Applied Physics, Royal Institute of Technology (KTH), Stockholm, Sweden ^*To whom correspondence should be addressed. Email: [e-mail]. Tel: [phone] <strong>The data files are grouped with respect to the figures/tables in the manuscript where the extracted results are presented. </strong> <strong>ABSTRACT</strong> Photodynamic therapy (PDT) relies on local generation of PDT precursor states in added photosensitizers (PS), such as triplet and photo-radical states. These states are strongly influenced by local oxygenation, pH and redox conditions, which thus are important to consider when optimizing PDT sessions. In practice however, monitoring of such conditions at PDT targeted sites is difficult, and further complicated by the fact that they can vary significantly, e.g. at a tumor lesion, with stage, type and localization of the lesion, and also during an ongoing treatment. For the same reasons, it is also difficult to quantify local effects of compounds added to promote triplet or photo-radical state formation of a PS. Consequently, the clinical use of such PDT adjuvant compounds is to date very limited. Method: We present here a transient state (TRAST) monitoring procedure, in which the fluorescence intensity response to systematically varied modulation of the excitation light was used to locally monitor PDT precursor states of PS compounds. Results: In solution measurements, photophysical models for two PS compounds, methylene blue (MB) and IRdye700DX (IR700), were determined, together with their transitions rates into triplet and photo-ionized states and their dependence on oxygenation, pH and redox conditions. By a fiber-optical arrangement, using one and the same fiber for both excitation and fluorescence detection, the PDT precursor state kinetics of locally applied MB and IR700 could then be monitored in a tissue sample. Finally, potassium iodide and ascorbate were added as possible PDT adjuvants, with capacity to enhance intersystem crossing and photoreduction, respectively. Adjuvant effects on the PDT precursor states of MB and IR700 were then monitored in solution and locally in tissue. Conclusion: The developed procedure allows PDT precursor states of PS compounds to be followed <em>in situ, </em>and how they are influenced by local environmental conditions, by applied excitation and added PDT adjuvants. Applying this procedure in PDT sessions can add important feedback, also during ongoing treatments, guiding application of excitation and identifying PDT adjuvants, resulting in more efficient and targeted PDT treatments.