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dc.contributor.authorHarada, T.en
dc.contributor.authorLincoln, S.en
dc.contributor.authorKee, T.en
dc.identifier.citationPhysical Chemistry Chemical Physics, 2016; 18(40):28125-28133en
dc.description.abstractCurcumin is a yellow polyphenol with multiple medicinal effects. These effects, however, are limited due to its poor aqueous stability and solubility. A hydrogel of 3% octadecyl randomly substituted polyacrylate (PAAC18) has been shown to provide high aqueous stability for curcumin under physiological conditions, offering a route for photodynamic therapy. In this study, the excited-state photophysics of curcumin in the PAAC18 hydrogel is investigated using a combination of femtosecond transient absorption and fluorescence upconversion spectroscopy. The transient absorption results reveal a multiexponential decay in the excited-state kinetics with fast (1 ps & 15 ps) and slow (110 ps & ≈5 ns) components. The fast decay component exhibits a deuterium isotope effect with D2O in the hydrogel, indicating that the 15 ps decay component is attributable to excited-state intramolecular hydrogen atom transfer of curcumin in the PAAC18 hydrogel. In addition, solvent reorganisation of excited-state curcumin is investigated using multiwavelength femtosecond fluorescence upconversion spectroscopy. The results show that the dominant solvation response (τ = 0.08 ps) is a fast inertial motion owing to the presence of bulk-like water in the vicinity of the hydrophobic octadecyl substituents of the PAAC18 hydrogel. The results also show an additional response with longer time constants of 1 and 6 ps, which is attributable to translational diffusion of confined water molecules in the three-dimensional, cross-linking network of the octadecyl substituents of PAAC18. Overall, we show that excited-state intramolecular hydrogen atom transfer and solvent reorganisation are major photophysical events for curcumin in the PAAC18 hydrogel.en
dc.description.statementofresponsibilityTakaaki Harada, Stephen F. Lincoln and Tak W. Keeen
dc.publisherRoyal Society of Chemistryen
dc.rightsThis journal is © the Owner Societies 2016en
dc.subjectCurcumin; Hydrogels; Solvents; Spectrometry, Fluorescence; Solubility; Hydrophobic and Hydrophilic Interactionsen
dc.titleExcited-state dynamics of the medicinal pigment curcumin in a hydrogelen
dc.typeJournal articleen
pubs.library.collectionBiochemistry publicationsen
dc.identifier.orcidKee, T. [0000-0002-4907-4663]en
Appears in Collections:Biochemistry publications

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