(442e) Rose Bengal Conjugated with Carbon Nanotube for Photodynamic and Hyperthermic Cancer Phototherapy

Rose Bengal (RB) is a water-soluble xanthene dye, known to produce singlet oxygen with a high absorption coefficient in the visible region of the spectrum. Although RB has the potential as a photosensitizer for photodynamic therapy (PDT), the clinical application of RB in PDT has been hampered due to insufficient lipophilicity and lack of tumor-accumulating property. Carbon nanotube (CNT) has recently been considered as a thermal-coupling agent for localized hypothermic therapy under near-infrared (NIR) laser exposure. In this study, RB and folic acid were coupled with CNT with the aid of Sb2O3 as a catalyst. UV-Vis, FT-IR, and XPS spectral analysis confirmed the chemical binding of RB and folic acid on CNT. RB-tagged CNTs functionalized with folate moiety were incubated with MCF-7 breast cancer cells for 6 and 24 hours, respectively. After replaced with fresh culture media, cell culture plates were first exposed with 540-nm LED light (4 J/cm2) and then followed with 808-nm NIR laser (600 mW/cm2) for 3 min. The amount of singlet oxygen triggered by RB detected by sensing probe Singlet Oxygen Sensor Green was increased significantly for MCF-7 cells first challenged with FA-CNT-RB for 24 hours and then sequentially exposed with LED light and NIR laser. The cell viability determined by MTT assay revealed 90% eradiation rate for cells treated with RB-CNT-FA which is much better than cells treated with CNT-FA (60% killing rate) and RB-CNT (40% killing rate).