An engineered cascade-sensitized red-emitting upconversion nanoplatform with a tandem hydrophobic hydration-shell and metal-phenolic network decoration for single 808 nm triggered simultaneous tumor PDT and PTT enhanced CDT

Abstract

Near-infrared light (NIR) driven lanthanide-doped upconversion nanoparticle (UCNP) based photo-dynamic therapy (PDT) holds a great promise for the non-invasive treatment of deep-seated tumors. However, it has also been highly hindered by the low upconversion luminescence (UCL) efficiency, hypoxia nature of solid tumors, and low therapeutic efficiency using single modality. Herein, we present a novel Nd³⁺ → Yb³⁺ → Tm³⁺ → Er³⁺ cascade-sensitized red-emitting UCNP with tandem hydrophobic hydration-shell (HHS) and metal-phenolic network (Fe-tannic acid, Fe-TA) decoration (UCNP@HHS@Fe-TA, denoted as UCFS@Fe-TA) for single 808 nm triggered simultaneous tumor PDT and photothermal therapy (PTT) enhanced chemo-dynamic therapy (CDT). The UCNP can supply intense red emission under high tissue penetrating/minimized tissue overheating 808 nm excitation, and their HHS coating with perfluorocarbon/photosensitizer Ce6 co-doping can not only realize UCL-based PDT, but also strengthen PDT of as-formed UCFS via O₂-carrying/UCL protection capacity of the HHS. Fe-TA coating can supply 808 nm triggered PTT, and the rise in temperature during PTT leads to enhanced Fenton catalytic activity of Fe-TA and faster ˙OH production rate of CDT to match with the real-timely released ¹O₂ in PDT. The as-designed UCFS@Fe-TA thus can achieve a single 808 nm triggered simultaneous PDT and PTT enhanced CDT, leading to a PTT-assisted reactive oxygen species storm for efficient tumor suppression. Such a design also renders the nanoplatform lower cell dark toxicity. In addition, the single excitation-triggered multimodal therapy mode might address the excitation wavelength mismatch issue in dual laser-triggered PTT/PDT mode. This study has therefore presented an efficient nanotherapeutic platform enabling synergistic multimodal tumor therapies with high biocompatibility.