Organic phosphorescent nanoscintillator for low-dose X-ray-induced photodynamic therapy

Abstract

X-ray-induced photodynamic therapy utilizes penetrating X-rays to activate reactive oxygen species in deep tissues for cancer treatment, which combines the advantages of photodynamic therapy and radiotherapy. Conventional therapy usually requires heavy-metal-containing inorganic scintillators and organic photosensitizers to generate singlet oxygen. Here, we report a more convenient strategy for X-ray-induced photodynamic therapy based on a class of organic phosphorescence nanoscintillators, that act in a dual capacity as scintillators and photosensitizers. The resulting low dose of 0.4 Gy and negligible adverse effects demonstrate the great potential for the treatment of deep tumours. These findings provide an optional route that leverages the optical properties of purely organic scintillators for deep-tissue photodynamic therapy. Furthermore, these organic nanoscintillators offer an opportunity to expand applications in the fields of biomaterials and nanobiotechnology.

Emerging Nanoagents for Medical X-ray Imaging

“…A smart combination of high- Z components and surface coating of SiO 2 , protein, lipid, polymer, and other compounds has led to increased X-ray imaging sensitivity and added biospecific protectors. A list of newly developed X-ray imaging nanoagents with rapid clearance, long blood circulation, and radiation therapy has been presented in Table . ,,,− In addition to the conventional X-ray contrast nanoagents, the recent emergence of X-ray luminescence nanoagents has also enabled them to become attractive candidates for high-performance X-ray imaging. Such new nanoagents can not only provide clear structural information in anatomical details but also endow chemical mapping at a molecular or cellular level.…”

“…The as-prepared metal chalcogenide nanoagents showed high biological safety and desirable therapeutic outcome, while rapid excretion and clear imaging were realized in 4T1 breast tumor-bearing mice (Figure d). Moreover, Wang et al reported the use of organic phosphorescent nanoagents as photosensitizers to activate the generation of reactive oxygen species for X-ray-induced photodynamic therapy in deep tissues under a low-dose X-ray excitation (0.4 Gy) …”

Stimulus-Responsive Organic Phosphorescence Materials Based on Small Molecular Host–Guest Doped Systems

“…Organic luminescence materials can be excited not only by UV light but also by bombardment of ionizing radiation (such as X-rays or γ-rays) to achieve radioluminescence (RL). − However, traditional organic fluorescence molecules have weak X-ray absorption and inefficient exciton utilization . Recently, some organic phosphorescent materials with efficient triplet exciton harvesting have been designed for the preparation of novel scintillators. ,− An et al reported the introduction of heavy halogen atoms to achieve high-efficiency radioluminescence of metal-free organic molecules . The doped crystal containing intermolecular halogen bonding also verified the generality of heavy halogen atoms for X-ray-excited luminescence.…”

“…Because the long-lived triplet excitons effectively minimize the influence of biological autofluorescence and background interference and potentially interact with molecular oxygen to generate reactive oxygen species, RTP materials can be potentially used for high-resolution time-resolved bioimaging and photodynamic therapy. − There is an urgent need to expand the application of host–guest doped RTP materials in practical bioapplications. Additionally, the development of RTP materials with infrared or near-infrared phosphorescence emission that can be excited by low-energy visible light or high-energy X-rays irradiation will accelerate the bioapplications of host–guest doped materials . Briefly, this emerging field deserves to be given more attention.…”

Catalytic nanotechnology of X-ray photodynamics for cancer treatments

“…Various attempts have always been made to advance the development of X-PDT. 72–75 In the early stage, X-PDT used fluoride and oxide as transducers. Subsequently, new materials were also developed and mainly investigated focusing on in vitro doses selected for RT.…”