Plasmon-Triggered Upconversion Emissions and Hot Carrier Injection for Combinatorial Photothermal and Photodynamic Cancer Therapy

Abstract

Despite the unique ability of lanthanide-doped upconversion nanoparticles (UCNPs) to convert near-infrared (NIR) light to high-energy UV−vis radiation, low quantum efficiency has rendered their application unpractical in biomedical fields. Here, we report anatase titania-coated plasmonic gold nanorods decorated with UCNPs (Au NR@aTiO 2 @UCNPs) for combinational photothermal and photodynamic therapy to treat cancer. Our novel architecture employs the incorporation of an anatase titanium dioxide (aTiO 2 ) photosensitizer as a spacer and exploits the localized surface plasmon resonance (LSPR) properties of the Au core. The LSPR-derived near-field enhancement induces a threefold boost of upconversion emissions, which are re-absorbed by neighboring aTiO 2 and Au nanocomponents. Photocatalytic experiments strongly infer that LSPR-induced hot electrons are injected into the conduction band of aTiO 2 , generating reactive oxygen species. As phototherapeutic agents, our hybrid nanostructures show remarkable in vitro anticancer effect under NIR light [28.0% cancer cell viability against Au NR@aTiO 2 (77.3%) and UCNP@aTiO 2 (98.8%)] ascribed to the efficient radical formation and LSPR-induced heat generation, with cancer cell death primarily following an apoptotic pathway. In vivo animal studies further confirm the tumor suppression ability of Au NR@aTiO 2 @UCNPs through combinatorial photothermal and photodynamic effect. Our hybrid nanomaterials emerge as excellent multifunctional phototherapy agents, providing a valuable addition to light-triggered cancer treatments in deep tissue.

Tuning Near‐Infrared‐to‐Ultraviolet Upconversion in Lanthanide‐Doped Nanoparticles for Biomedical Applications

“…Although the combination of UCNPs and TiO 2 can be used to generate ROS and kill cancer cells, the low quantum efficiency of the UCNPs has limited its further application. Recently, Kim and co-workers reported a nanostructure composed of Au NR@ aTiO 2 @UCNPs, [89] in which Au core can enhance the upconversion emission of the UCNPs by localized surface plasmon resonance (LSPR) for effective activation of TiO 2 photosensitizers. In their work, the cancer cell viability through Au NR@ aTiO 2 @UCNPs nanocomposites treated was 28% compared to Au NR@aTiO 2 (77.3%) and UCNP@aTiO 2 (98.8%).…”

Iron selenide nanorods for light-activated anticancer and catalytic applications

“…There is still a significant need for multifunctional therapeutic agents with a broad absorption range and minimal toxicity which combine ROS generation and PTT functions into a single nanoplatform. [23][24][25] Due to their broadband absorption in the visible range, iron selenide (FeSe) nanoparticles can be used as promising photothermal agents.…”

Synthesis of Methotrexate-Loaded Dumbbell-Shaped Titanium Dioxide/Gold Nanorods Coated with Mesoporous Silica and Decorated with Upconversion Nanoparticles for Near-Infrared-Driven Trimodal Cancer Treatment

“…Titanium dioxide (TiO 2 ) is a semiconductor photocatalyst that uses PS to generate ROS to improve PDT and has physical/chemical stability, low cost, nontoxicity, intense photostability, photon absorption, enhanced photocatalytic activity, excellent optical/electronic properties, charge separation/recombination, and biocompatibility. ,, TiO 2 can produce photoinduced electrons and holes that interface with the surrounding species to liberate ROS. The TiO 2 materials combined with UCNPs can absorb UV light from the UCNPs, which can undergo intense tissue penetration through photocatalytic activity toward cancer treatment.…”