Highly porous PEGylated Bi2S3 nano-urchins as a versatile platform for in vivo triple-modal imaging, photothermal therapy and drug delivery.

Biocompatible single-component nanoplatforms simultaneously integrating multiple therapeutic functions with multiple imaging modes are desirable for anticancer treatments. Herein, elaborately-designed highly porous PEGylated bismuth sulfide nano-urchins (Bi2S3-PEG NUs) have been successfully synthesized by using Bi2O3 nanospheres as the sacrificial template via the hydrothermal process. It is demonstrated that the Bi2S3-PEG NUs possess high compatibility, stability, X-ray attenuation ability, near-infrared (NIR) absorbance and photothermal conversion capability, without noticeable toxicity. Based on both in vitro and in vivo results, the product shows excellent performance in highly effective photothermal therapy (PTT) guided by triple-modal imaging, including X-ray computed tomography (CT), and photoacoustic (PA) and infrared thermal (IRT) imaging, without noticeable toxicity in vivo. Importantly, the NUs are highly porous with a high specific surface area and copious mesopores, providing high loading capacity to accommodate drugs (or guest biomolecules) for further applications in chemotherapy and other additional functions. Doxorubicin is loaded as an example, showing a rather high loading capacity (∼37.9%) together with a bimodal on-demand pH/photothermal-sensitive drug release property. Such fascinating multifunctional nanoagents may have considerable applications in antitumor diagnosis and therapy in the clinic.