Water-soluble sulfonate porphyrin functionalized hyaluronic acid with comb-like structure: Potential photosensitizers for photodynamic therapy

A water-soluble comb-like porphyrin polymer based on hyaluronic acid ( HA ) as the main chain and sulfonate substituted tetraphenylporphyrin ( TASP ) as side groups, named as HA- g -NH-TPP-(SO 3 Na) [( HA- g -TASP )], was designed and synthesized, which could be used as a potential photosensitizer in photodynamic therapy (PDT). This photosensitizer displayed high-water solubility, low dark cytotoxicity, high photocytoxiticy and high singlet oxygen yield ( Φ Δ  = 0.86). The HA- g -TASP was carefully characterized by UV–Vis, FTIR, and 1 H NMR. UV–Vis spectra showed the Q bands of the HA- g -TASP spectrum had a significant red shift about 50 nm to near-infrared (NIR) region compared with TASP , the HA- g -TASP had a smaller energy band gap . The NIR region is known as the transparent window of the organisms, NIR irradiation shows larger penetration distance in tissue. As a novel photosensitizer, HA- g -TASP exhibited low cytotoxicity in dark and also low photocytotoxicity towards normal cells, but performed enhanced photodynamic activity against cancer cells (HeLa cells). As a result, HA- g -TASP with comb-like structure may be a useful photosensitizer for practical photodynamic therapy in the future.