TY - JOUR U1 - Zeitschriftenartikel, wissenschaftlich - begutachtet (reviewed) A1 - Liu, Quan A1 - Wackenhut, Frank A1 - Hauler, Otto A1 - Scholz, Miriam A1 - Zur Oven-Krockhaus, Sven A1 - Ritz, Rainer A1 - Adam, Pierre-Michel A1 - Brecht, Marc T1 - Hypericin: single molecule spectroscopy of an active natural drug JF - The journal of physical chemistry. A. Molecules, spectroscopy, kinetics, environment & general theory N2 - Hypericin is one of the most efficient photosensitizers used in photodynamic tumor therapy (PDT). The reported treatments of this drug reach from antidepressive, antineoplastic, antitumor and antiviral activity. We show that hypericin can be optically detected down to a single molecule at ambient conditions. Hypericin can even be observed inside of a cancer cell, which implies that this drug can be directly used for advanced microscopy techniques (PALM, spt-PALM, or FLIM). Its photostability is large enough to obtain single molecule fluorescence, surface enhanced Raman spectra (SERS), fluorescence lifetime, antibunching, and blinking dynamics. Sudden spectral changes can be associated with a reorientation of the molecule on the particle surface. These properties of hypericin are very sensitive to the local environment. Comparison of DFT calculations with SERS spectra show that both the neutral and deprotonated form of hypericin can be observed on the single molecule and ensemble level. Y1 - 2020 SN - 1089-5639 SS - 1089-5639 U6 - https://doi.org/10.1021/acs.jpca.9b11532 DO - https://doi.org/10.1021/acs.jpca.9b11532 VL - 124 IS - 12 SP - 2497 EP - 2504 S1 - 8 PB - American Chemical Society CY - Washington, DC ER -