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To integrate photodynamic therapy (PDT) with photothermal therapy (PTT) and chemotherapy for enhanced antitumor efficiency, we developed a mild and rational route to synthesize novel multifunctional GdOF:Ln@SiO2 (Ln = 10%Yb/1%Er/4%Mn) mesoporous capsules using strong up-conversion luminescent (UCL) GdOF:Ln as cores and mesoporous silica layer as shells, followed by modification with varied functional groups onto the framework. It was found that due to the codoped Yb/Er/Mn in GdOF, the markedly enhanced red emission can efficiently transfer energy to the conjugated PDT agent (ZnPc) which produces high singlet oxygen, and the incorporated carbon dots outside the shell can generate obvious thermal effect under 980 nm laser irradiation and also prevent the premature leaking of ZnPc. Simultaneously, the as-produced thermal effect can obviously enhance the doxorubicin (DOX) release, which greatly improves the chemotherapy, resulting in a synergistic therapeutic effect. The system exhibits drastically enhanced therapeutic efficiency against tumor growth, as demonstrated both in vitro and in vivo. Especially, the doped rare earth ions in the host endow the material with excellent UCL imaging, magnetic resonance imaging (MRI), and computed tomography (CT) imaging properties, thus realizing the target of multimodal imaging guided multiple therapies.

Photodynamic therapy (PDT), as a minimally invasive and high‐efficiency anticancer approach, has received extensive research attention recently. Despite plenty of effort devoted to exploring various types of photodynamic agents with strong near‐infrared (NIR) absorbance for PDT and many encouraging progresses achieved in the area, effective and safe photodynamic photosensitizers with good biodegradability and biocompatibility are still highly expected. In this work, a novel nanocomposite has been developed by assembly of iron oxide (Fe3O4) nanoparticles (NPs) and Au nanoparticles on black phosphorus sheets (BPs@Au@Fe3O4), which shows a broad light absorption band and a photodegradable character. In vitro and in vivo assay indicates that BPs@Au@Fe3O4 nanoparticles are highly biocompatible and exhibit excellent tumor inhibition efficacy owing to a synergistic photothermal and photodynamic therapy mediated by a low‐power NIR laser. Importantly, BPs@Au@Fe3O4 can anticipatorily suppress tumor growth by visualized synergistic therapy with the help of magnetic resonance imaging (MRI). This work presents the first combination application of the photodynamic and photothermal effect deriving from black phosphorus nanosheets and plasmonic photothermal effect from Au nanoparticles together with MRI from Fe3O4 NPs, which may open the new utilization of black phosphorus nanosheets in biomedicine, optoelectronic devices, and photocatalysis.

A proper photosensitizer and increased penetration depth are still two major challenges in photodynamic therapy (PDT). The conventional ultraviolet/visible irradiation light has low tissue penetration, which thus limits its clinical application. Herein, we for the first time designed a novel multifunctional composite by integrating NaGdF4:Yb,Er@Yb@Nd@Yb upconversion nanoparticles (UCNPs) and black phosphorus sheets (BPS) for a single 808 nm laser light-mediated PDT. UCNPs, which served as the energy donor, were modified with poly­(acrylic acid), and the BPS were stabilized by the PEG-NH2; then the two counterparts were integrated into the UCNPs–BPS composite via electrostatic interaction. Under 808 nm near-infrared light irradiation, the composite exhibits excellent antitumor efficiency because of the large amount of reactive oxygen species generated compared with those under 650 and 980 nm irradiations with the same pump power, which has evidently been confirmed by in vitro and in vivo results. In particular, our work may pave the way for the wide application of black phosphorus-based materials in theranostics.

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