Near-Infrared Light-Triggered Polyprodrug/siRNA Loaded Upconversion Nanoparticles for Multi-Modality Imaging and Synergistic Cancer Therapy.

Stimuli-responsive nanosystems have been widely applied as effective modalities for drug/gene co-delivery in cancer treatment. However, precise spatiotemporal manipulations of drug/gene co-delivery, as well as multi-modality imaging-guided cancer therapy, still remain a daunting challenge. Here, multifunctional polyprodrug/siRNA loaded upconversion nanoparticles (UCNPs) are reported that combine computed tomography (CT), magnetic resonance (MR), and upconversion luminescence (UCL) tri-modality imaging and near-infrared (NIR) light-activated drug/gene on-demand delivery. The photoactivatable platinum(IV) (Pt(IV))-backbone polymers (PPt) and the siRNA targeting polo-like kinase 1 (Plk1) are loaded on the surface of polyethyleneimine (PEI)-coated UCNPs (PUCNP) to obtain the multifunctional polyprodrug/siRNA loaded UCNPs (PUCNP@Pt@siPlk1). The PUCNP@Pt@siPlk1 can be served as a "nanotransducer" to convert NIR light (980 nm) into local ultraviolet (UV) to visible light for the cleavage of photosensitive PPt, resulting in the simultaneous on-demand release of high toxic platinum(II) (Pt(II)) and siPlk1. Meanwhile, the PUCNP@Pt@siPlk1 has CT, T -weighted MR, and UCL tri-modality imaging abilities. Based on these merits, PUCNP@Pt@siPlk1 displayed excellent synergistic therapeutic efficacy via image-guided and NIR light-activated platinum-based chemotherapy and RNA interfering in vitro and in vivo. Thus, this developed nanosystem with NIR light-controlled drug/gene delivery and multi-modality imaging abilities, will display great potential in combining chemotherapy and gene therapy.