Abstract
Rose bengal is an anionic dye considered as a potential photosensitizer for anticancer photodynamic therapy. The clinical utility of rose bengal is hampered by its short half-life, limited transmembrane transport, aggregation, and self-quenching; consequently, efficient drug carriers that overcome these obstacles are urgently required. In this study, we performed multilevel in vitro and in silico characterization of interactions between rose bengal and cationic poly(amidoamine) (PAMAM) and poly(propyleneimine) (PPI) dendrimers of the third and fourth generation and assessed the ability of the resultant complexes to modulate the photosensitizing properties of the drug. We focused on explaining the molecular basis of this phenomenon and proved that the generation- and structure-dependent binding of the dye by the dendrimers increases the cellular uptake and production of singlet oxygen and intracellular reactive oxygen species, leading to an increase in phototoxicity. We conclude that the application of dendrimer carriers could enable the design of efficient photodynamic therapies based on rose bengal.
Highlights
Photodynamic therapy (PDT) is one of the most promising methods for the treatment of basal cell carcinoma and different types of skin cancer.[1]
Using Job’s method,[22] we approximated the stoichiometry of binding in fully saturated complexes as 1:27 for PPI G3:RB, 1:33 for PPI G4:RB, 1:20 for PAMAM G3:RB, and 1:34 for PAMAM G4:RB (Figure 1, insets)
Based on the titration curves, we determined the stoichiometry of the formed complexes; the resultant values were similar to those obtained by spectrofluorimetric analyses: 1:21 for PPI G3:RB, 1:33 for PPI G4:RB, 1:22 for PAMAM G3:RB, and 1:26 for PAMAM G4:RB (Figure 2)
Summary
Photodynamic therapy (PDT) is one of the most promising methods for the treatment of basal cell carcinoma and different types of skin cancer.[1] This highly specific approach is primarily based on the application of a light-sensitive compound (socalled photosensitizer, PS), which, upon excitation with light of a certain wavelength, generates reactive oxygen species (ROS). This, in turn, leads to the oxidation of cellular nucleic acids, lipids, and proteins, disrupting cell signaling cascades or gene regulation and activating several cell death pathways.[2] Such a specific mechanism enables treatment to be targeted precisely to the area of a neoplastic lesion upon direct application of PS and light.[3] the benefits of PDT are its noninvasiveness and lack of adverse side effects. To take full advantage of the potential of PDT, it is essential to select the appropriate phototoxic drug
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