All-in-one nanoagents with a single-component and all-required functions have attracted increasing attention for the imaging-guided
therapy of
tumors, but the design and preparation of such nanoagents remain a challenge. Herein, we report the introduction of
oxygen vacancies to traditional
semiconductors with
heavy-metal elements for tuning photoabsorption in the near infrared (NIR) region, by using
Bi2WO6 (band-gap: ∼2.7 eV) as a model. Bi2WO6-x nanodots with sizes of ∼3 or ∼8 nm have been prepared by a facile coprecipitation-solvothermal method assisted by
citric acid (CA, 0.1-1.5 g) as the reduction agent. CA confers the removal of O atoms from the [Bi2O2]2+ layer during the solvothermal process, resulting in the formation of plenty of
oxygen vacancies in the Bi2WO6-x crystal. As a result, NIR photoabsorption of Bi2WO6-x nanodots can be remarkably enhanced with the increase of the CA amount from 0 to 1.0 g. Under irradiation of a single-wavelength (808 nm, 1.0 W cm-2) NIR
laser, black Bi2WO6-x-CA1.0 nanodots can not only efficiently produce a sufficient amount of heat with a photothermal conversion efficiency of 45.1% for
photothermal therapy, but also generate
singlet oxygen (1O2) for
photodynamic therapy. Furthermore, due to the presence of
heavy-metal (Bi and W) elements, Bi2WO6-x-CA1.0 nanodots have high X-ray attenuation ability for CT imaging. After the Bi2WO6-x-CA1.0 nanodot dispersion is injected into the
tumor-bearing mice, the
tumor can be imaged by using CT and an IR thermal camera. After irradiation with a single-wavelength (808 nm, 1.0 W cm-2, 10 min) NIR
laser, the
tumor can be completely suppressed by the synergic photothermal and photodynamic effects of Bi2WO6-x-CA1.0 nanodots, without recurrence and treatment-induced toxicity. Therefore, Bi2WO6-x nanodots have great potential as a novel all-in-one nanoagent for the imaging and
phototherapy of
tumors.