Nanoparticle-Mediated X-Ray-Induced Photodynamic Therapy

Nanoparticle-mediated X-ray-induced photodynamic therapy (X-PDT) is an emerging cancer treatment that integrates the deep-tissue penetration of X-rays with the reactive oxygen species (ROS) generation characteristic of photodynamic therapy (PDT). In X-PDT, high-Z or organic nanoscintillators absorb X-ray energy and convert it into luminescence, which in turn activates conjugated photosensitisers to produce cytotoxic ROS such as singlet oxygen. This approach overcomes the depth limitations of conventional light-activated PDT and augments the therapeutic index by combining radiotherapy and PDT effects. Advances in nanoparticle design—including the development of purely organic scintillators, heteroatom-doped constructs and multifunctional coatings—have improved X-ray absorption, energy transfer efficiency and biocompatibility. Preclinical studies demonstrate potent antitumour activity under low radiation doses, heightened tolerance to hypoxia and opportunities for image guidance. Clinical translation will depend on optimising nanoparticle pharmacokinetics, minimising off-target toxicity and refining dosimetry for combined modality regimens.

Research from Nature Portfolio

Recent studies have introduced purely organic phosphorescent nanoscintillators that dual-role as scintillators and photosensitisers, achieving effective singlet oxygen generation at low X-ray doses (0.4 Gy) with negligible adverse effects. These organic constructs eliminate the need for heavy metals while demonstrating bright luminescence and deep-tumour antitumour efficacy in vivo. Foundational work on inorganic nanoparticle–photosensitiser conjugates using cerium fluoride cores and verteporfin molecules established high singlet oxygen quantum yields under X-ray irradiation and confirmed enhanced cell killing with clinical radiation energies. Together, these reports validate the feasibility of X-ray activation of nanoparticle systems to supplement or replace conventional radiotherapy.

Nanoparticle-Mediated X-Ray-Induced Photodynamic Therapy publication trend

The graph below shows the total number of articles in nanoparticle-mediated x-ray-induced photodynamic therapy across all publications each year (not limited to Nature Index journals).

Technical terms

X-ray-induced photodynamic therapy (X-PDT): A treatment modality that uses X-rays to excite nanoparticles which then activate photosensitisers to generate cytotoxic reactive oxygen species.

Photosensitiser: A light-absorbing molecule that transfers energy to molecular oxygen on activation to produce reactive oxygen species.

Nanoscintillator: A nanoscale material that converts high-energy X-rays into lower-energy photons for in situ activation of photosensitisers.

Reactive oxygen species (ROS): Highly reactive molecules, including free radicals and peroxides, that induce cellular damage and apoptosis in photodynamic therapy.

Singlet oxygen (¹O₂): A highly cytotoxic form of molecular oxygen generated during photodynamic processes that causes oxidative damage to cellular components.

References

1. Nanoscintillator-Mediated X-Ray Induced Photodynamic Therapy for Deep-Seated Tumors: From Concept to Biomedical Applications. Theranostics (2020).
2. Organic phosphorescent nanoscintillator for low-dose X-ray-induced photodynamic therapy. Nature Communications (2022).
3. X-ray induced singlet oxygen generation by nanoparticle-photosensitizer conjugates for photodynamic therapy: determination of singlet oxygen quantum yield. Scientific Reports (2016).
4. Pure Organic AIE Nanoscintillator for X‐ray Mediated Type I and Type II Photodynamic Therapy. Advanced Science (2023).