Molecular Electronic Tuning of Photosensitizers to Enhance Photodynamic Therapy: Synthetic Dicyanobacteriochlorins as a Case Study

作者：Yang, Eunkyung; Diers, James R.; Huang, Ying-Ying; Hamblin, Michael R.; Lindsey, Jonathan S.^*; Bocian, David F.; Holten, Dewey

来源：Photochemistry and Photobiology, 2013, 89(3): 605-618.

DOI：10.1111/php.12021

• CENTRAL METAL
• BACTERIOCHLORINS
• OXYGEN
• SUBSTITUENTS
• PORPHYRINS
• GENERATION
• SPECTRA
• SENSITIZERS
• MELANOMA
• EFFICACY

Photophysical, photostability, electrochemical and molecular-orbital characteristics are analyzed for a set of stable dicyanobacteriochlorins that are promising photosensitizers for photodynamic therapy (PDT). The bacteriochlorins are the parent compound (BC), dicyano derivative (NC)2BC and corresponding zinc (NC)2BC-Zn and palladium chelate (NC)2BC-Pd. The order of PDT activity against HeLa human cancer cells in vitro is (NC)2BC-Pd>(NC)2BC>(NC)2BC-Zn approximate to BC. The near-infrared absorption feature of each dicyanobacteriochlorin is bathochromically shifted 3550nm (748763nm) from that for BC (713nm). Intersystem crossing to the PDT-active triplet excited state is essentially quantitative for (NC)2BC-Pd. Phosphorescence from (NC)2BC-Pd occurs at 1122nm (1.1eV). This value and the measured ground-state redox potentials fix the triplet excited-state redox properties, which underpin PDT activity via Type-1 (electron transfer) pathways. A perhaps counterintuitive (but readily explicable) result is that of the three dicyanobacteriochlorins, the photosensitizer with the shortest triplet lifetime (7s), (NC)2BC-Pd has the highest activity. Photostabilities of the dicyanobacteriochlorins and other bacteriochlorins studied recently are investigated and discussed in terms of four phenomena: aggregation, reduction, oxidation and chemical reaction. Collectively, the results and analysis provide fundamental insights concerning the molecular design of PDT agents.

• 出版日期2013-6
• 单位MIT; 广西医科大学