Mini Review of TiO₂‐Based Multifunctional Nanocomposites for Near‐Infrared Light–Responsive Phototherapy

Abstract

Phototherapy with the properties of specific spatial/temporal selectivity and minimal invasiveness has been acknowledged as one of the most promising cancer therapy types. Among all the photoactive substance for phototherapy, titanium dioxide (TiO ) nanomaterials are paid more and more attention due to their outstanding photocatalytic properties, prominent biocompatibility, and excellent chemical stability. However, the wide bandgap (3.0-3.2 eV) of TiO limits its absorption only to the ultraviolet (UV) light region. For a long time, UV light-stimulated TiO was applied in the phototherapy researches of tumors located in the skin layer, while it is unsatisfactory for most deep-tissue tumors. Due to the maximum penetration into tissue existing in the near-infrared (NIR) region, how to use NIR light to trigger photochemical reaction of TiO remains a big challenge. In this review, two strategies to develop and construct NIR-triggered TiO -based nanocomposites (NCs) for phototherapy are summarized, and the relevant mechanism and background knowledge of TiO -based phototherapy are also given in order to better understand the application value and current situation of TiO in phototherapy. Finally, the challenges and research directions of TiO in the future clinic phototherapy application are also discussed.

Visible‐Light Responsive TiO2‐Based Materials for Efficient Solar Energy Utilization

“…In the past decades, much effort has been devoted to the fabrication of advanced TiO 2 materials for photocatalysis, and some excellent reviews have been published, covering black TiO 2 , [32][33][34][35] or heteroatom-doped TiO 2 , [36][37] or TiO 2based nanocomposites. [38][39][40] These reviews partly discussed TiO 2 materials with enhanced visible-light adsorption in a specific category. However, a comprehensive overview on basic design principles and synthetic methods for visiblelight responsive TiO 2 is lacking.…”

Type I Photosensitizers Revitalizing Photodynamic Oncotherapy

“…Meanwhile, electron receptors (e.g., O 2 and H + ) can directly accept one electron from the photosensitized TiO 2 , resulting in the generation of O 2 •− and H 2 O 2 . [ 85 ] Due to the remarkable photocatalytic performance, the UV irradiation excited TiO 2 can cause damage to cancer cell lines. Nevertheless, the UV‐light utilized in the treatment may also bring about damages to human immune systems and surface tissues (e.g., skin and eyes).…”

NIR-absorbing superoxide radical and hyperthermia photogenerator via twisted donor-acceptor-donor molecular rotation for hypoxic tumor eradication

“…In the previous research, O 2 −• could be produced for cancer therapies by some inorganic or organic reagents under light irradiation, and thus this O 2 −• -based PDT (type I PDT) is a potential cancer treatment for merits of non-invasiveness, low systemic-toxicity and high selectivity. In comparison with inorganic O 2 −• generators (e.g., metaloxide nanoparticles (NPs) and metal-organic frameworks) [30][31][32][33], organic O 2 −• photogenerators have attracted extensive attention due to their biodegradability and reduced pharmacokinetic complexity. Despite the tremendous advances, there is remarkable scope to improve the performance of organic O 2 −• photogenerators.…”