Combination of photodynamic therapy and gene silencing achieved through the hierarchical self-assembly of porphyrin-siRNA complexes.

In this work, we implemented a supramolecular approach in order to combine photodynamic therapy (PDT) with gene therapy. We made use of a simple cationic guanidylated porphyrin (H2‑PG) with the hypothesis that porphyrin aggregates should be capable of complexing siRNA through multivalent interactions and thus contribute to its intracellular delivery, while remaining active photosensitizers for PDT. The PDT effect of H2‑PG was shown by incubating human breast cancer cells (MDA-MB-231) with H2‑PG followed by light-irradiation at 405 nm. On the other hand, while siRNA do not enter cells alone, we showed, by fluorescence confocal microscopy and flow cytometry, that H2‑PG promotes the internalization of Atto-488 siRNA. Finally, studying the combined PDT and delivery of siRNA directed against inhibitory apoptotic protein (IAP) family, we found an additive effect of the two therapies, thereby demonstrating that H2‑PG is capable of acting both as a photosensitizer and supramolecular siRNA vector.