Abstract: Cuprous iodide cluster-based complexes exhibit significant potential in scintillator materials due to their structural diversity, strong X-ray absorption capacity, and tunable excited-state properties. However, crystalline state is typically required to achieve efficient luminescence, and mechanical grinding often induces mechanochromic effects, which severely limit their biomedical applications. In this study, a series of Cu4I4Py4 complex-based scintillators were prepared via a facile solution processing method. The effects of crystal structure, co-crystallized solvent molecule, and polymer matrix on their luminescent performance were systematically investigated. In addition, polystyrene (PS) was employed as an encapsulation matrix to modulate the emission wavelength of the scintillators, enabling spectral overlap with the photosensitizer (methylene blue, MB) for enhanced energy transfer efficiency. The encapsulation simultaneously improved biocompatibility and bioenvironmental stability of the scintillation complex, yielding a type of photosensitizer nanoparticles (Cu4I4Py4-PS-MB) with high X-ray irradiation resistance. The results of RNO bleaching (RNO-imidazole) experiments confirmed that this nanocomposite system exhibits exceptionally high singlet oxygen (1O2) yields under both UV light and X-ray irradiation, demonstrating its potential for constructing efficient and stable X-ray photodynamic therapy (X-PDT) nanoplatform. This work provides a novel solution for deep-tumor photodynamic therapy by overcoming the limitations of traditional scintillator materials.

Key words: Cuprous iodide cluster complex, X-ray scintillator, Deep tumor therapy, Photodynamic therapy.