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Table 5 Radiolabeling studies performed on scandium radionuclides

From: Production of scandium radionuclides for theranostic applications: towards standardization of quality requirements

Type of vector RN used Buffer, pH, T°, time conditions Quality Control / RCY Molar activity Post-radiolabeling purification Reference
DOTA 44Sc 0.2 M ammonium acetate
pH = 4.8
80 °C
30 min
iTLC with H2O 51 GBq/μmol competitive metal impurities of 28 μM (mostly Fe) Not indicated (Severin et al. 2012)
DTPA
HEBD
BAPTA
EGTA
TTHA
DFO
DOTA
47Sc 20 mM acetate buffer
pH = 6.0
RT
iTLC
with NH3/H2O (1/25)
DTPA
RCY = 38.8–100%
EGTA
RCY = 97.2–100%
DOTA
RCY = 79.4–97.7%
Estimation 0.017 MBq/nmol Not performed (Severin et al. 2012; Polosak et al. 2013)
picagaDUPA 44Sc 0.25 M NaOAc buffer solution
pH = 4
at 25 or 80 °C.
TLC
with 50 mM EDTA
RCY = 83% at 25 °C
RCY = 96% at 80 °C
Calculated from (Polosak et al. 2013) 0.03 MBq/nmol Not performed (Vaughn et al. 2020a)
AAZTA-c(RGDfK) 44Sc 0.25 M ammonium acetate
pH = 4
room temperature
5 min
RCY = 99% 0.36 GBq/μmol   (Nagy et al. 2017a; Vaughn et al. 2020a; Kostelnik and Orvig 2019)
Propargyl-DOTA 44Sc 95 °C for 30 min HPLC Phenomenex Synergi, 4 μ, Hydro-RP, 80 Å
a gradient with the eluents acetonitrile (A) and H2O (B), both containing 0.1% trifluoroacetic acid and a flow rate of 1.0 mL/min.
RCY = 69–92%
Other metals: Zn (5.4 ± 4.5 ppm), Fe (1.1 ± 0.7 ppm), Pb (0.38 ± 0.13 ppm) and Al (0.18 ± 0.14 ppm) Not performed (Hoehr et al. 2014)
DOTA - puromycin 44Sc 0.25 M ammonium acetate
pH =4
95 °C
20 min
iTLC
Elution with n-propanol/ NH4OH/H2O (55:35:10)
RCY = 78%
1.5 GBq/μmol HPLC - C-18 cartridge (Strata-X Polymeric Sorbet 60 mg/mL Phenomenex)
Elution with ethanol
Radiochemical purity ≥97%
(Eigner et al. 2013)
DOTA-Folate 44Sc 1 M ammonium acetate
pH 3.5–4
95 °C
10 min
HPLC - C-18 column (Xterra MS C18, Waters).
Mobile phase: Milli Q water with 0.1% trifluoracetic acid (A) and methanol (B) with a linear gradient from 95% A and 5% B to 20% A and 80% B over 25 min with a flow rate of 1 mL/min
RCY ≥ 96%
≥ 5.2 MBq/nmol, representing a 44Sc–to–ligand molar ratio of 1:5600 Not indicated (Muller et al. 2018)
47Sc CH3COONH4/HCl
pH 4.5
95 °C
10 min
HPLC as above
RCY ≥ 96%
no radionuclidic impurities were detectable
13 MBq/nmol
Not indicated (Muller et al. 2014)
PSMA-617 44Sc 0.25 M ammonium acetate
pH = 4
95 °C
25 min
iTLC 1:1 v/v 1 M ammonium acetate / methanol
RCY = 74%- 98%
1.82–6.69 MBq/nmol HPLC - C-18 cartridge (Sep-Pak C18 Plus Short Waters) - after a pre-conditioning with 4 mL of ethanol and 10 mL of water. Elution with pure ethanol. (Eppard 2018)
DOTANOC 44Sc 0.2 M sodium acetate buffer
pH 4
85 °C
15 min
HPLC C-18 (XterraTM MS column 95% MilliQ water with 0.1% trifluoracetic acid (A) and 5% acetonitrile (B) over a 20-min period at a flow rate of 1 mL/min
RCY ≥ 98%
  Not indicated (van der Meulen et al. 2015)
47Sc 0.5 M sodium acetate
pH 4.5
95 °C
15 min
HPLC C-18 (XterraTM MS column 95% MilliQ water with 0.1% trifluoracetic acid (A) and 5% acetonitrile (B) over a 20-min period at a flow rate of 1 mL/min
RCY ≥ 96%
10–25 MBq/nmol Not indicated (Domnanich et al. 2017a)
DOTATOC 44Sc 0.8 M ammonium acetate
pH = 5
91 °C
30 min
iTLC
RCY = 99%
1.4 MBq/μg Not indicated (Singh et al. 2017)
44Sc 0.25 M ammonium acetate
pH = 4
95 °C
30 min
iTLC
a) 0.1 M sodium citrate pH 4.0
(b) mixture of 5% NaCl with MeOH (3:1)
(c) mixture of 5% NaCl with MeOH and 25% NH3 (3:1:1)
RCY ≥ 98%
9 GBq/μmol Performed on RP C-18 mini-cartridge Strata-X Elution with pure ethanol (Kerdjoudj et al. 2016)
DOTATATE 44m/44Sc 0.1 M ammonium acetate
pH 4–6
70 °C
20 min
TLC
25% aq. NH3/H2O/MeOH, 2/1/1 (v/v)
RCY ≥ 95%
8 MBq/nmol
radionuclidic purity = 99%
Not performed (Huclier-Markai et al. 2018; Alliot et al. 2015a; Alliot et al. 2015b)
43Sc ammonium acetate
pH = 5
90 °C
35 min
TLC
0.1 M sodium citrate (pH = 5.0)
RCY = 98.3%
Not indicated Not performed (Szkliniarz et al. 2016)
CHX-A”-DTPA-Fab fragment of Cetuximab 44Sc 0.5 M sodium acetate buffer
pH 6.5 adjusted to 4.5
room temperature (25 °C)
30 min
TLC
50% aqueous acetonitrile
63 GBq/μmol PD-10 columns
PBS as the mobile phase
(Chakravarty et al. 2014)
DOTA
-ZHER2–2891
44Sc   RCY = 98% 7.8GBq/μmol   (Honarvar et al. 2017)