Two-photon induced luminescence, singlet oxygen generation, cellular uptake and photocytotoxic properties of amphiphilic Ru(ii) polypyridyl–porphyrin conjugates as potential bifunctional photodynamic therapeutic agents

Abstract

Two Ru(II) polypyridyl-porphyrin and Zn(II) porphyrin conjugates (Ru-L and Ru-Zn-L) have been synthesized and their photophysical properties studied. The two conjugates, which contained a hydrophobic tetraphenylporphyrin L conjugated via an acetylide linker at its β-position with a hydrophilic Ru(II) polypyridyl complex, showed high singlet oxygen quantum yields (>70%) and substantial two-photon absorption cross-sections (~500 GM). Ru-L gave strong emissions at ~660 and ~733 nm through linear or two-photon excitation. Solvatochromism was observed in the fluorescence spectra of Ru-L and Ru-Zn-L, where in less polar solvents (i.e., toluene and dichloromethane) their fluorescence emissions became slightly blue-shifted with a 3-fold reduction in intensity relative to those observed in polar solvents (i.e., acetonitrile and methanol). Cell-based studies of these complex conjugates were conducted using human nasopharyngeal carcinoma HK-1 and cervical carcinoma HeLa cells on which Ru-L showed rapid cellular uptake, low dark-cytotoxicity, and high photo-cytotoxicity. Furthermore, Ru-L can be excited and emits in the "biological window"in vitro, making it a potential potent new generation photodynamic therapeutic agent capable of singlet oxygen generation and in vitro near-infrared emission.

Two-photon luminescent metal complexes for bioimaging and cancer phototherapy

“…Their results indicated that with high singlet oxygen quantum yields (> 70%) and substantial two-photon absorption cross-sections (~500 GM), complex 12 could be excited and emit in the "biological window" in vitro. This makes it a potential potent new generation photodynamic therapeutic agent [247]. Without the ruthenium complex moiety, Zn-porphyrin derivatives can also act as two-photon PDT In addition to ruthenium complexes, Ir(III) complexes have also been applied as two-photon PDT agents.…”

Characterizing low fluence thresholds for in vitro photodynamic therapy

“…The singlet oxygen quantum yields for PpIX and TPPS 2a have not been studied using both blue and red light. However, a comparable porphyrin analogue, TPPS, was studied at 424 nm and 630 nm and was found to have similar singlet oxygen quantum yields of 0.69 and 0.58, respectively [25]. This would suggest that there shouldn't be a significant difference in the PDT efficiency for the two light sources when normalized for photon energy and extinction coefficients at the different wavelengths.…”

Multifunctional Cu39S28 hollow nanopeanuts for in vivo targeted photothermal chemotherapy

“…Therefore, it is necessary to develop new approaches with less invasive and more effective methods to treat breast cancer. With the development of nanomedicine, many new treatment approaches have emerged, 4–6 such as enhanced photodynamic, 4 microwave irradiation, 7 radiotherapy 8 and photothermal therapy 9 induced by various nanoparticles. Among these approaches, photothermal therapy (PTT) is an attractive alternative treatment for cancer therapy, especially for solid tumors, and it usually employs photothermal agents to ablate cancer cells without damaging the surrounding tissues under near infrared ray (NIR) radiation.…”