Targeted Photodynamic Activity of a Hyaluronic Acid–Protoporphyrin IX Complex via Receptor‐Mediated Endocytosis

in cancer cells [A549]) was approximately 10.3, demonstrating strong selectivity toward cancer cells. Further, the uptake of HA-1 in A549 cells was suppressed following the addition of free HA, indicating that its internalization occurred through CD44-receptor-mediated endocytosis. Moreover, the HA-1 complex exhibited better photodynamic activity against CD44-overexpressing cancer cells than both poly-L-lysine-1 complex and Photofrin, underscoring its potential as a targeted photosensitizer for photodynamic therapy.