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When exposed to X-rays, scintillators emit visible luminescence. X-ray-mediated optogenetics employs scintillators for remotely activating light-sensitive proteins in biological tissue through X-ray irradiation. This approach offers advantages over traditional optogenetics, allowing for deeper tissue penetration and wireless control. Here, we assessed the short-term safety and efficacy of candidate scintillator materials for neuronal control. Our analyses revealed that lead-free halide scintillators, such as Cs3Cu2I5, exhibited significant cytotoxicity within 24 h and induced neuroinflammatory effects when injected into the mouse brain. In contrast, cerium-doped gadolinium aluminum gallium garnet (Ce:GAGG) nanoparticles showed no detectable cytotoxicity within the same period, and injection into the mouse brain did not lead to observable neuroinflammation over four weeks. Electrophysiological recordings in the cerebral cortex of awake mice showed that X-ray-induced radioluminescence from Ce:GAGG nanoparticles reliably activated 45% of the neuronal population surrounding the implanted particles, a significantly higher activation rate than europium-doped GAGG (Eu:GAGG) microparticles, which activated only 10% of neurons. Furthermore, we established the cell-type specificity of this technique by using Ce:GAGG nanoparticles to selectively stimulate midbrain dopamine neurons. This technique was applied to freely behaving mice, allowing for wireless modulation of place preference behavior mediated by midbrain dopamine neurons. These findings highlight the unique suitability of Ce:GAGG nanoparticles for X-ray-mediated optogenetics. The deep tissue penetration, short-term safety, wireless neuronal control, and cell-type specificity of this system offer exciting possibilities for diverse neuroscience applications and therapeutic interventions. [ABSTRACT FROM AUTHOR]

CsPbBr3 quantum dots-embedded SiO2 glasses were synthesized by the spark plasma sintering method as novel scintillators for γ -ray detectors. Their optical and scintillation properties were investigated to examine the scintillation performance. The X-ray diffraction patterns observed a halo peak of the SiO2 glass phase and diffraction peaks of CsPbBr3. An emission peak due to CsPbBr3 quantum dots was detected at around 515 nm in both photoluminescence (PL) and scintillation spectra. The PL and scintillation decay time curves included a component of nanosecond order, resulting from CsPbBr3 quantum dots. Under γ -ray irradiation from 137Cs, the light yield (LY) of the 0.2% CsPbBr3-embedded SiO2 glass was 150 photons MeV−1. [ABSTRACT FROM AUTHOR]

Al(DMSO)6SbCl6 and Ga(DMSO)6SbCl6 single crystals were synthesized by the solvent evaporation method and their optical and scintillation properties were investigated. Broad photoluminescence (PL) and scintillation peaks derived from the recombination of the self-trapped excitons were confirmed at 500–550 nm. The calculated PL quantum yields of Al(DMSO)6SbCl6 and Ga(DMSO)6SbCl6 were, respectively, 99.0 and 92.2%. The PL and scintillation decay time constants were estimated to be approximately 2.0 µs. The afterglow levels at 20 ms after X-ray irradiation for 2 ms were obtained to be 98 ppm (Al(DMSO)6SbCl6) and 63 ppm (Ga(DMSO)6SbCl6). The light yields (LY) of Al(DMSO)6SbCl6 and Ga(DMSO)6SbCl6 were 1100 and 800 photons/MeV under 137Cs γ-rays (662 keV) exposure. [ABSTRACT FROM AUTHOR]

Dy-doped Ba3Y(PO4)3 single crystals were grown by the floating zone (FZ) method, and the photoluminescence (PL) and thermally stimulated luminescence (TSL) properties were evaluated. The highest PL quantum yield value was obtained from the 5% Dy-doped sample. The Dy-doped sample displayed PL emission peaks at 480, 580, 670, and 760 nm when excitation wavelengths were 325, 350, and 385 nm. The peaks were caused by the 4f–4f transitions of Dy3+. The Dy-doped samples also represented TSL peaks due to the 4f–4f transitions of Dy3+ when they were heated at 65 and 80 °C. The 1% Dy-doped sample showed the highest TSL intensity, and the TSL signal was detectable from 0.01 mGy. [ABSTRACT FROM AUTHOR]

Pr-doped (Lu1− x , Y x )2Si2O7 (x = 0.25, 0.5, and 0.75) crystals were synthesized by the floating zone method. Emission peaks due to 5d–4f transitions of Pr3+ were observed at 300 nm under excitation of both UV light and X-rays. Scintillation decay times of 19–22 ns were obtained, and they originated from the 5d–4f transitions of Pr3+. Afterglow levels became high from 64.7 to 541 ppm as the Y-admixed concentration increased. The light yields were estimated to be 560–700 photons MeV−1 by comparing the channels of photoabsorption peaks from the pulse height spectra of 137Cs γ -rays measured using prepared crystals and commercial Gd2SiO5 reference. [ABSTRACT FROM AUTHOR]

Mg4Ta2O9 single crystals doped with 0.01, 0.1, and 1% Er were grown using the floating zone method, and their photoluminescence and scintillation properties were studied. X-ray diffraction analysis confirmed that all samples had a hexagonal structure of Mg4Ta2O9. The samples showed that the emission peak at 1550 nm was due to 4f−4f transitions of Er3+ ions, with quantum yields of 32.9, 46.6, and 18.0% for 0.01, 0.1, and 1% doping concentrations, respectively. All samples showed scintillation with a broad emission band at 350 nm due to charge transfer from Ta5+ to O2− ions and emission peak at 1550 nm due to 4f−4f transition of Er3+ ions. The dose rate response functions showed that the detection limit for all samples was 0.06 Gy/h for scintillation detector applications. [ABSTRACT FROM AUTHOR]