Design and Synthesis of a Lead Sulfide Based Nanotheranostic Agent for Computer Tomography/Magnetic Resonance Dual-Mode-Bioimaging-Guided Photothermal Therapy

Dual-modality-imaging-guided photothermal therapy (PTT) exhibits great potential in the field of diagnosis and treatment. Herein, we report a controllable method (atom-transfer radical polymerization) for the preparation of gadolinium(III)-complex-grafted lead sulfide (GCGLS) nanoparticles. A series of characterizations (such as TEM, HR-TEM, EDX, XRD, FTIR, etc.) prove that GCGLS nanoparticles have been successfully prepared. The GCGLS nanoparticles with ultrasmall sizes (ca. 11 nm) have quite strong photoabsorption intensity in the near-infrared (NIR) region because of a low S vacancy concentration of lead sulfide. As the addition amount of gadolinium(III) complexes increases, the sizes of the GCGLS nanoparticles show no evidence of changing. The temperature of the GCGLS nanoparticle solution can quickly elevate to 57.5 °C in 10 min after NIR laser irradiation (1.5 W cm–2) at 808 nm; this result reveals that it possesses high photothermal conversion efficiency (∼31%). When the GCGLS nanoparticles are injected into the mice, it is clearly observed that there is efficient accumulation in the tumor site. Moreover, the GCGLS nanoparticles also show excellent prominent X-ray computer tomography (CT) and T1-weighted magnetic resonance (T1-MR) imaging in vitro/vivo. By the combination of GCGLS and NIR laser irradiation, an effective tumor treatment experiment is conducted in mice. Therefore, the prepared GCGLS nanoparticles with dual-modality-imaging-guided PTT can be used as potential diagnosis and treatment reagents for clinical applications.