Abstract
TiO2 nanoparticles modified with phthalocyanines (Pc) have been proven to be a potential photosensitizer in the application of photodynamic therapy (PDT). However, the generation of reactive oxygen species (ROS) by TiO2 nanoparticles modified with Pc has not been demonstrated clearly. In this study, nitrogen-doped TiO2 conjugated with Pc (N-TiO2-Pc) were studied by means of monitoring the generation of ROS. The absorbance and photokilling effect on HeLa cells upon visible light of different regions were also studied and compared with non-doped TiO2-Pc and Pc. Both N-TiO2-Pc and TiO2-Pc can be activated by visible light and exhibited much higher photokilling effect on HeLa cells than Pc. In addition, nitrogen-doping can greatly enhance the formation of 1O2 and •O2−, while it suppresses the generation of OH•. This resulted in significant photodynamic activity. Therefore, N-TiO2-Pc can be an excellent candidate for a photosensitizer in PDT with wide-spectrum visible irradiation.
Highlights
Titanium dioxide (TiO2) nanoparticles have been widely studied in many fields such as solar cells, electrochromic devices, environment, and biomedicine [1,2]
Researchers have focused on the application of photodynamic therapy (PDT) due to its low toxicity, high stability, excellent biocompatibility, and unique photocatalytic properties
When TiO2 is photoexcited upon UV irradiation, hole-electron pairs are generated, which result in the formation of reactive oxygen species (ROS) via the redox reactions of oxygen or water molecules at the TiO2 surface
Summary
Titanium dioxide (TiO2) nanoparticles have been widely studied in many fields such as solar cells, electrochromic devices, environment, and biomedicine [1,2]. The generated ROS can induce a remarkable photokilling effect against cancer cells [3,4,5]. When doped or modified with different methods, TiO2 nanoparticles may become an attractive photosensitizer (PS) under visible light irradiation. TiO2 nanoparticles modified with phthalocyanine have been proven to be promising as PSs with enhanced absorption in the visible region [6,7]. There have been some studies showing that TiO2 nanoparticles can generate specific ROS such as hydroxyl radicals (OH) [9] and superoxide anion.
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