Complexes of functionalized quantum dots and chlorin e₆ in photodynamic therapy

Abstract

Recently, it has been suggested that quantum dots (QDs) could be used in the photodynamic therapy of cancer as resonance energy donors for conventional porphyrin type photosensitizers. Here we present the results of the spectroscopic studies on the formation of a non-covalent complex between QDs and photosensitizer chlorin Ce 6 in an aqueous medium and in the presence of bovine serum albumin (BSA). Changes in the absorption and fluorescence spectra of QDs and Ce 6 revealed the formation of a QD-Ce 6 complex which occurs due to hydrophobic interaction between the nonpolar moiety of an amphiphilic photosensitizer and the hydrophobic part of the lipid-based coating of the QD. The photosensitizer conjugated with the QD could be indirectly excited by the Forster resonance energy transfer (FRET) from the QD to Ce 6 . The investigation on the capacity of such complex to generate 1 O 2 showed that the QD-Ce 6 complex irradiated by visible light is able to produce 1 O 2 more efficiently than QDs or Ce 6 taken separately. The photoinactivation of cells incubated with the QD-Ce 6 complex and irradiated in the spectral region where the photosensitizer does not absorb provided evidence that such complex could induce FRET-mediated cell destruction.

Structural and Functional Consequences of the Weak Binding of Chlorin e6 to Bovine Rhodopsin

“…In this spectrum there are bathochromic shifts of the Soret band to 407 nm and the 655 nm peak in the Q‐band to 665 nm, both known to be associated with aggregation and acidification . These shifts indicate complex formation between bovine rhodopsin and Ce6, analogous to the complex formation of Ce6 with polyvinylpyrrolidone and quantum dots .…”

The influence of phthalocyanine aggregation in complexes with CdSe/ZnS quantum dots on the photophysical properties of the complexes

“…However, in many other QD–tetrapyrrole systems real FRET efficiency was significantly lower than was predicted by evaluation of donor–acceptor distance and spectral overlap integral between donor emission and acceptor absorption bands [9,18–21]. This statement was recently supported by the Nyokong group [22] where FRET efficiencies up to 93% were predicted in nanocomposites based on glutathione-capped CdTe/CdS/ZnS QDs covalently linked with aluminium sulfonated phthalocyanine.…”

pH-Sensitive self-assembling nanoparticles for tumor near-infrared fluorescence imaging and chemo–photodynamic combination therapy

“…b Measured using dynamic light scattering (DLS), data represent mean ± SD, n = 3. environment. 37 As a result, the Ce6 was successfully encapsulated into the TCAD NPs. The hydrodynamic diameter of TCAD NPs (196.0 nm) and TCAD@Ce6 NPs (160.0 nm) in the range of 50-200 nm (Fig.…”