Dynamically tuning near-infrared-induced photothermal performances of TiO₂ nanocrystals by Nb doping for imaging-guided photothermal therapy of tumors

Abstract

Conventional wide bandgap semiconductors can absorb UV/visible light but have no photoabsorption band in the near-infrared (NIR) region, leading to difficulty in their use as NIR-responsive agents. With TiO as an example, we report the tuning from UV-responsive TiO nanocrystals to blue TiO nanocrystals with newly appeared NIR absorption band through the Nb-doping strategy. A strong NIR band should result from the localized surface plasmon resonances due to the considerable free electrons originating from the efficient incorporation of Nb ions (<15.5%). Interestingly, under the irradiation of a 1064 nm laser, Nb-doped TiO nanocrystals can convert laser energy into heat, and higher Nb-doping content can lead to higher NIR-induced temperature elevation, highlighting that the photothermal performances of TiO nanocrystals can be dynamically modulated by adjusting the Nb-doping levels. After coating with PEGylated phospholipid, the resulting nanocrystals display water dispersibility, high photothermal conversion efficiency and cytocompatibility. Therefore, these Nb-doped TiO nanocrystals can be used as efficient and heavy-metal-free nanoagents for the simultaneous NIR/photoacoustic imaging and photothermal therapy of tumors using a 1064 nm laser in the second biological window.

Exogenous Physical Irradiation on Titania Semiconductors: Materials Chemistry and Tumor‐Specific Nanomedicine

“…g) The relative HeLa tumor‐volume changes as a function of feeding time after different treatments as shown in the figure. Reproduced with permission . Copyright 2017, Royal Society of Chemistry.…”

“…In addition to the mostly explored high‐temperature treatment strategy to obtain black TiO 2 nanoparticle for PTT against cancer, Chen and co‐workers successfully converted UV‐responsive TiO 2 nanoparticles to blue TiO 2 nanocrystals by a simple Nb‐doping approach . The different Nb‐doping amount induced varied morphology of TiO 2 nanocrystals with high dispersity (Figure e).…”

Biocompatible tumor-targeting nanocomposites based on CuS for tumor imaging and photothermal therapy

“…11,12 Therefore, a variety of multifunctional nanoparticles are widely used in cancer diagnosis and treatment. 13,14 Copper sulde nanoparticles (CuS NPs) are featured with prominent absorbance and effective heat conversion effect, small particle size, easy modication, and simple preparation. It can be used as a functional component to combine with other diagnostic contrast agents, and then the multi-functional nanocomposite are obtained.…”

Photoacoustic imaging and photothermal therapy in the second near-infrared window

“…However, its absorption band can be effectively adjusted to the NIR region through the Nb-doping method. 70 An Nb-doped TiO 2 nanoagent could convert light energy into heat under the illumination of a 1064 nm laser; thus, PTT can be realized. WO 3Àx nanostructures with strong NIR absorption rooted in the LSPR of free electrons have been used as PTT agents; 71 however, their PTT in the NIR-II window has rarely been developed due to insufficient photothermal conversion efficiency.…”