Introduction
Scintillation mechanism
Inorganic scintillators
Scintillation at the nanoscale
Background
Advantages and disadvantages of NCSs
Suitability of nanostructured scintillators for various applications
Tab.1 Comparison of the RL intensity of NCSs and BSCs [82]. Copyright 2014. Reproduced with permission from Elsevier |
nanocrystalline @ 50-keV X-rays | single crystal @ 662-keV gamma rays | ||||||
---|---|---|---|---|---|---|---|
sample name (abbreviation) | formula | crystallite size /nm | relative intensity (%BGO) between 300 and 400 nm | relative intensity (%BGO) between 200 and 1000 nm | formula | luminosity (photons/MeV) | relative luminosity (%BGO) between 200 and 1000 nm |
BGO | Bi4Ge3O12 | 20 | 100 | 100 | Bi4Ge3O12 | 7200 | 100 |
Y3Al5O12 (undoped) | 12190 | 149 | |||||
YAG | Y3Al5O12 | 80 | 491 | 30 | Y3Al5O12:Pr (0.08%) | 14700 | 180 |
YAG:Pr (1%) | Y3Al5O12:Pr | 80 | 3414 | 141 | Y3Al5O12:Pr (0.1%) | 19440 | 270 |
YAG:Pr (0.75%) | Y3Al5O12:Pr | 80 | 2620 | 118 | Y3Al5O12:Pr (0.16%) | 13770 | 131 |
YAG:Pr (1.25%) | Y3Al5O12:Pr | 80 | 2660 | 98 | Y3Al5O12:Pr (0.24%) | 15500 | 190 |
YAG:Pr (1%)@ SiO2 | Y3Al5O12:Pr@SiO2 | 120 | 855 | 42 | Y3Al5O12:Pr (0.25%) | 16000 | 222 |
YAG:Pr (1.5%) | Y3Al5O12:Pr | 90 | 2960 | 120 | Y3Al5O12:Pr (0.33%) | 15610 | 216 |
YAG:Pr (1.75%) | Y3Al5O12:Pr | 90 | 2620 | 94 | Y3Al5O12:Pr (0.6%) | 11600 | 140 |
Y3Al5O12:Pr (0.65%) | 14670 | 203 | |||||
Y3Al5O12:Pr (0.8%) | 8000 | 111 | |||||
LSAO:Pr (0.5%) | (La,Sr)AlO4:Pr | 190 | 4 | 9 | (La,Sr)AlO4:Pr | - | - |
GSO:Ce (10%) | Gd2Si2O7:Ce (10%) | 120 | 782 | 41 | Gd2Si2O7:Ce | 12500 | 174 |
GYGAG:Pr (1%)Gd | (Gd0.7,Y0.3)3(Al0.5,Ga0.5)5O12:Pr (1%) | 100 | 255 | 116 | (Gd,Y)3A5O12:Pr (1%) | - | - |
GYGAG:Pr (1%)Ga | (Gd0.5,Y0.5)3(Al0.3,Ga0.7)5O12:Pr (1%) | 100 | 1220 | 49 | Y3(Ga,Al)5O12:Pr (1%) | - | - |
LYSO:Pr (1%)CR | (Lu,Y)2SiO5 (1%) | 90 | 350 | 65 | (Lu,Y)2SiO5:Ce (LYSO) | 27000 | 375 |
LYSO:Pr (1%)SP | (Lu,Y)2SiO5 (1%) | 20 | 44 | 29 | Lu1.8Y0.2SiO5:Ce (LYSO) | 34000 | 472 |
BaF2 | BaF2 | 50 | 78 | 3 | BaF2 single crystal | 3900/10000 | 54/139 |
Important characteristics governing the properties of the nanoscintillators
Structural effect
Surface effect
Fig.7 RL spectra of (a) the La2Zr2O7:Eu3+ NPs [126] (Copyright 2011. Reproduced with permission from Elsevier), (b) Gd2O3:Eu3+ [127] (Copyright 2013. Reproduced with permission from the Department of Materials Science and Engineering, University of Florida, Gainesville, Florida and (c) the BaF2:Ce3+ NPs [127] (Copyright 2013. Reproduced with permission from the Department of Materials Science and Engineering, University of Florida, Gainesville, Florida) |
Fig.8 RL spectra of the (a) Gd2O2S:Eu3+ NPs [123] (Copyright 2011. Reproduced with permission from the Royal Society of Chemistry), (b) LaF3:Eu3+ NPs [128] (Copyright 2010. Reproduced with permission from IEEE), (c) BaF3:Ce NPs [128] (Copyright 2010. Reproduced with permission from IEEE), and (d) HfO2 NPs [137] (Copyright 2017. Reproduced with permission from the Japan Society of Applied Physics) |
Quantum confinement
Fig.9 Scintillation output of the quantum dot nanoporous glass composites under (a) a and (b) γ irradiation. Both the pulse height spectra were corrected from the background radiation. A Gaussian fit of the 59-keV line of americium-241 shown in the inset indicates an experimental energy resolution DE/E of 15% at this energy [146] (Copyright 2006. Reproduced with permission from the American Chemical Society). (c) Scintillation temporal behavior of (n-C6H13NH3)2PbI4 measured with the streak camera and fitted with the sum of two or one exponential decays [147] (Copyright 2014. Reproduced with permission from the Japan Society of Applied Physics) |
Dielectric confinement
Various compositions of nanoscintillators
Oxide-based nanoscintillators
Fig.11 RL spectra of the (a) La2Hf2O7:Pr3+ NPs [36] (Copyright 2018. Reproduced with permission from Royal Society of Chemistry), (b) La2Hf2O7:Eu3+ NPs [40] (Copyright 2017. Reproduced with permission from Elsevier), and (c) La2Hf2O7:Ce3+ bulk microcrystalline powder [159] (Copyright 2012. Reproduced with permission from Elsevier) |
Fluoride-based nanoscintillators
Organic–inorganic nanocomposites (OINC)
Fig.13 RL spectra of the (a) PMMA:Gd3Ga3Al2O12:Ce (GGAG:Ce) film under different X-ray tube voltages [165] (Copyright 2017. Reproduced with permission from the American Chemical Society), (b) BaF2 NPs:polystyrene film having different NP sizes [166] (Copyright 2016. Reproduced with permission from Elsevier), and (c) SrF2 NPs:polystyrene film having different NP sizes. Curve 7 represents the spectrum of the SrF2 microcrystalline powder pellet having the same thickness as the film [167] (Copyright 2017. Reproduced with permission from Elsevier) |
Cluster compounds
Fig.14 (a) Synthesis of Hf–MOF and Zr–MOF and (b) X-ray-induced generation of fast photoelectrons from heavy Hf and Zr metals followed by the scintillation of the anthracene-based linkers in the visible spectrum [31]. Copyright 2014. Reproduced with permission from the American Chemical Society |
Fig.15 RL signals of the Hf–MOF, Zr–MOF, and control samples (from left to right): HfO2 and ZrO2 colloidal NPs, H2L alone, H2L+ HfO2 colloid, H2L+ ZrO2 colloid, Hf–MOF, and Zr–MOF. The concentration of H2L, Hf, or Zr in the samples is 1.2 mM. The X-ray dosages are 1 Gy/10 s with an effective X-ray energy of ~18.9 keV (40-kV tube voltage and 0.08-mA tube current) and a detection gain of 200. (b) RL signals of Hf–MOF and Zr–MOF with different concentrations and radiation tube voltages [31]. Copyright 2014. Reproduced with permission from the American Chemical Society |
Physical forms of nanoscintillators
Nanoparticles (NPs)
Fig.16 (a) RL spectra of the BaF2 NPs having different sizes [174] (Copyright 2014. Reproduced with permission from AIP), (b) RL spectra of the CaF2 NPs having different sizes [186] (Copyright 2012. Reproduced with permission from AIP), and (c) RL spectra of the LuPO4:Ce NPs [188] (Copyright 2014. Reproduced with permission from Elsevier) |
Thin films
Nanoceramics
Glass
Applications of nanoscintillators
Ionizing radiation detection
Fig.21 (a) γ and α energy spectra derived from the 133Ba and 241Am isotopes, respectively, attenuated through 3.7-cm air by irradiating a 1 cm × 1 cm thin composite assembly of para-MEH–PPV and PbSe NPs. The spectra were obtained for various durations, as shown in the legend. The inset shows a TEM micrograph of PbSe NPs under assembly. (b) Typical 133Ba spectra derived from a thin detector in which the Pb and Se X-ray escape peaks are prominent [202] |
X-ray-induced photodynamic therapy (XPDT)
Tab.2 Different nanoscintillators exploited for XPDT [108]. Copyright 2018. Reproduced with permission from Impact Journals, LLC |
year | Nanoparticle | size | nanoparticle concentration | photosensitizer | X-ray energy | biological model |
---|---|---|---|---|---|---|
2008 | LaF3:Tb3+ | 15 nm | 0.035 M* | Meso-tetra (4-carboxyphenyl) porphine (MTCP) | 120 keV | N/A |
2010 | ZnO nanorods (NRs) | 0.5 mm | N/A | P rotoporphyrin dimethyl ester (PPDME) | N/A | T47D cells |
2011 | Y2O3 | 12 nm | 2.5–95 mg/mL | Psoralen | 2 Gy, 160 or 320 kVp | PC3 cells |
2011 | Gd2O2S:Tb | 20 mm | 5 mg/mL | Photofrin II | 120 keV, 20 mAs | human glioblastoma cells |
2013 | Tb2O3 | 10 nm | 1 mM | Porphyrin | N/A | N/A |
2013 | ZnO | 50 nm | 0.3–0.6 mM | Mesi-tetra (4-sulfonatophenyl) porphyrin (TSPP) | N/A | Escherichia coli |
2014 | LaF3:Ce3+ | 2 mm | 1 mg/mL | Protoporphyrin IX (PPIX) | 3 Gy | PC3 cells |
2016 | Sr2MgSi2O7:Eu2+, Dy3+ | 273 nm | 10 mg/mL | Protoporphyrin IX (PPIX) | 1–7 Gy | PC3 |
2014 | Cu–Cy | 50–100 nm | 50 mg | Self | 5 Gy | MCF-7 Xenograft |
2016 | AnS:Cu, Co | 4 nm | 0.05 mM | Tetrabromorhodamine-123 (TBrRh123) | 2 Gy | PC3 cells |
2015 | SrAl2O4:Eu2+ | 80 nm | 50 mg/mL | Merocyanine 540 (MC540) | 0.5 Gy | U87MG Xenograft |
2015 | LaF3:Tb | 3–45 nm | N/A | Rose Bengal (RB) | 2–10 keV | N/A |
2015 | LaF3:Tb | 3–45 nm | 20 mg/mL | Rose Bengal (RB) | N/A | tumor model |
2016 | CeF3 | 7–11 nm | 0.1–0.9 mM | Veterporfin (VP) | 6 Gy, 8 keV, or 6 MeV | Panc-1 |
2015 | LiYF4:Ce3+ | 34 nm | 25–50 mg/mL | ZnO | 8 Gy | HeLa cells |
2015 | SiC/SiOx NWs | 20 nm | 50 mg/mL | Porphyrin | 2 Gy, 6 MV | A549 cells |
2015 | ZnO/SiO3 | 98 nm | 0.005–0.05 M | ZnO | 200 kVp, 2 Gy | LNCaP and Du145 cells |
2015 | GdEuC12 micelle | 4.6 nm | 500 mM | Hypericin (Hyp) | 5–40 keV | HeLa cells |
Note: * 1 M= 1 mol/L |
Fig.23 (a) Scintillating NPs serve as an X-ray transducer to generate 1O2 through the energy transfer process. (b) Diagram of the PDT mechanism that occurs when energy is transferred from the ScNPs to activate the PS. PS’s electrons from the ground state (S0) absorb energy and move to singlet-excited states (S1) [1]. Copyright 2016. Reproduced with permission from the American chemical society |