Chlorin e6–ZnSe/ZnS quantum dots based system as reagent for photodynamic therapy

Abstract

Stable water-soluble complexes of Cd-free ZnSe/ZnS quantum dots (QDs) and chlorin e6 complexes have been prepared. These complexes have shown approximately 50% intracomplex fluorescence resonance energy transfer from QDs to chlorin e6. The photodynamic therapy (PDT) test of the complexes against the Erlich acsite carcinoma cell culture demonstrated a two-fold enhancement of the cancer cell photodynamic destruction as compared to that of free chlorin e6 molecules. It was shown that the PDT effect was significantly increased due to two factors: the efficient QD-chlorin e6 photoexcitation energy transfer and the improvement of cellular uptake of the photosensitizer in the presence of ZnSe/ZnS QDs.

Strategies for optimizing the delivery to tumors of macrocyclic photosensitizers used in photodynamic therapy (PDT)

“…Several examples of Cd-based QDs conjugated with PSs have been reported in literature [156][157][158] and used for cancer PDT in vitro, but the main disadvantage of such nanosystems is related to the elevated metal-induced cytotoxicity, limiting in vivo applications. As an alternative, ZnSe/ZnS quantum dots complexed with the PS Ce6 were synthetized as stable and water-soluble nanosystems [159]. The authors reported a very efficient QD to Ce6 intracomplex photoexcitation energy transfer (almost 50% FRET efficiency) that significantly improved PDT efficacy in EAC carcinoma cells in vitro due to synergistic effects of FRET mediated PDT and improved cellular uptake of Ce6 delivered by QDs with respect to the PS delivered in the free form.…”

Photoluminescent nanoplatforms in biomedical applications

“…As well, Föster Resonance Energy Transfer (FRET) has been proposed for the activation of PS to enhance the production of ROS [165,166]. Martynenko et al employed ZnSe/ZnS QDs as energy donors for chlorin-Ce6 PS molecules [167]. In vitro experiments revealed that the conjugation of the PS molecules with the QDs resulted in a twofold enhancement in the killing of the cancer cell in comparison to the free Ce6 molecules.…”

Energy transfer efficiency in quantum dot/chlorin e6 complexes

“…Due to the efficient photoexcitation energy transfer (ET), singlet oxygen generation of tetrapyrrole compound can be enhanced. Accordingly, photodynamic effect of QD/tetrapyrrole system can be significantly higher compared to that of free tetrapyrrole [7].…”