A Water-Soluble Tetra Cationic Porphyrin and its Palladium Complex: Highly Effective Photosensitizers Against an Aggressive Type of Breast Cancer

We report a water-soluble tetracationic porphyrin and its Pd²⁺ complex as candidate photosensitizers for photodynamic therapy against the aggressive triple-negative breast cancer cell line MDA-MB-231. We describe the synthesis of the metalloporphyrin and determine IC₅₀ values for both compounds under dark and light conditions. Only upon light irradiation both agents exhibit potent cytotoxicity, with remarkably low IC₅₀ values in the nanomolar range, underscoring their photoactivated selectivity. These findings highlight the strong potential of both the free-base porphyrin and its palladium complex as photodynamically active sensitizers and motivate further studies on mechanism, formulation, and in vivo efficacy.