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The coupling of ZnO-based nanomaterials with organic photosensitizers (PS) is potentially interesting for cancer treatment under X-ray. In these conditions, ZnO nanoparticles (NPs) convert the X-ray into UV-Vis emission, promoting the PS excitation and producing reactive oxygen species (ROS). Main advantages for in vivo applications are ZnO photostability and biocompatibility, even if its efficient coupling with different PS (typically porphyrin) is still a controversial issue, as both a high ZnO luminescence yield and a good overlapping of ZnO emission-PS absorption spectra are necessary, along with a suitable energy transfer between ZnO and PS. In this perspective, the aim is the investigation of the optical properties of an ad-hoc system composed of porphyrin functionalized ZnO NPs anchored on SiO2 NPs (ZnO/SiO2). The goal is the understanding of the optimal conditions for a good energy transfer efficiency of ZnO-porphyrin structures, including the role of ZnO-PS proximity, to promote their application in anti-cancer therapies and imaging with ionizing radiations. First, amorphous ZnO NPs of 5-6 nm were anchored onto SiO2 NPs (~80 nm); then, ZnO/SiO2 was functionalized with different porphyrin contents (tetrakis(4-carboxyphenyl)porphyrin, TCPP, 0.3 – 3.0 wt%) by exploiting a silane grafting agent (3-aminopropyl)triethoxysilane. The structural characterization demonstrated that increasing TCPP amounts were bonded to SiO2 depending on the TCPP loading. The optical properties were preliminary tested in dimethylformamide, used as solvent reaction for TCPP anchoring on SiO2. The Photoluminescence Analysis (PL) revealed a high luminescence of ZnO NPs and the occurrence of a radiative energy transfer between ZnO and TCPP, that was not visible in a mechanical mixing of ZnO and TCCP, highlighting their optical interaction upon functionalization. Besides, TCPP emission was hugely enhanced under X-ray in the Radioluminescence (RL), whereas no enhancement was detectable in t

Rare earths-doped silica optical fibers have shown promising results for ionizing radiation monitoring, thanks to their radio-luminescence (RL) properties. However, the use of these systems for accurate and precise dosimetric measurements in radiation fields above the Cerenkov energy threshold, like those employed in radiation therapy, is still challenging, since a spurious luminescence, namely the "stem effect" is also generated in the passive fiber portion exposed to radiation. The spurious signal mainly occurs in the UV-VIS region, therefore a dopant emitting in the near infrared may be suitable for an optical discrimination of the stem effect. In this work, the RL and dosimetric properties of Yb-doped silica optical fibers, produced by sol-gel technique, are studied, together with the methods and instruments to achieve an efficient optical detection of the Yb3+ emission, characterized by a sharp line at about 975 nm. The results demonstrate that the RL of Yb3+ is free from any spectral superposition with the spurious luminescence. This aspect, in addition with the suitable linearity, reproducibility, and sensitivity properties of the Yb-doped fibers, paves the way to their use in applications where an efficient stem effect removal is required.

In this paper different sol gel syntheses strategies are adopted in order to produce Ce - doped silica - glasses scintillators with improved properties. Variations on the synthesis procedure are adopted to reduce the hydroxyl content of the sol gel glass; to this purpose, a fluorine derivative of silicon alkoxide was added in the sol gel reaction. Since a drawback of Ce - doped sol gel glasses is the partial oxidation of Ce3+ to Ce4+ in the matrix probably occurring during the sintering procedure, both Ce - doped xerogel and fluorinated xerogel were treated under reducing atmosphere (H 2:Ar) instead of the usual oxidizing atmosphere. Glasses obtained in such ways are compared with commercial synthetic glasses and with previously produced sol gel samples by spectroscopic IR absorption measurements, and by radio-luminescence experiments.