Synthesis of [11C]PBR06 and [18F]PBR06 as agents for positron emission tomographic (PET) imaging of the translocator protein (TSPO)

Fully automated synthesis of [18F]T807, a PET tau tracer for Alzheimer’s disease

“…[20][21][22][23][24] However, the solubility of T807P in DMSO is not very high, and thus F-18 labeling yield was low. 18 To reduce excess amount of the unreacted precursor T807P (1 mg) to amino-T807, huge amount of Fe powder (90-100 mg) need to be used, thus it is not easy to perform routine automation, and instead manual synthesis is required.…”

“…Several modifications have been made to improve the chemical purity and specific activity (SA) of the target tracer [ 18 F]T807. Addition of NaHCO 3 to quench the radiolabeling reaction and to dilute the radiolabeling mixture prior to the injection onto the semi-preparative HPLC column for purification [20][21][22][23] gave better separation of labeled product […”

“…Although this modification helped to shorten the overall production time, it potentially could bring the organic solvent residue issue (CH 3 CN from mobile phase) since CH 3 CN residue has limit restriction for clinical usage. In addition, to our F-18 labeling experiences on F-18 tracers, 16,[20][21][22][23] although the HPLC systems we employed have shown good separation of products from precursors, there always was a co-elution of the F-18 labeled product with its corresponding precursor from the HPLC column, very tiny amount of the precursor (0.1-0.3 g/mL) contaminating the tracer solution. [ 18 F]T807 was also in the same case.…”

Synthesis and preliminary biological evaluation of [11C]methyl (2-amino-5-(benzylthio)thiazolo[4,5-d]pyrimidin-7-yl)-d-leucinate for the fractalkine receptor (CX3CR1)

“…The product was isolated by semi-preparative reversephase (RP) high performance liquid chromatography (HPLC) with a C-18 column, and then concentrated by solid-phase extraction (SPE) 14 The radiosynthesis process included three stages: 1) labeling reaction; 2) purification; and 3) formulation. The radiolabeled precursor we used is more reactive confirmed the aforementioned result.…”

Synthesis of [11C]MK-1064 as a new PET radioligand for imaging of orexin-2 receptor

“…For the radiotracer produced for human study, we used ethanol (2 × 1 mL), no evaporation required, and a C-18 Sep-Pak was used for direct reformulation. [22][23][24][25] We have tried to use a C-18 Light Sep-Pak cartridge instead of a C-18 Plus Sep-Pak cartridge to allow smaller volume (1 mL) of ethanol and to avoid laborious rotary evaporation before formulation. However, there is more serious back pressure in the Light Sep-Pak than in the Plus Sep-Pak, in addition, dead volume in the transfer tubing also affects the elution, and thus it is more difficult to efficiently elute the labeled product from a Light SepPak, which resulted in the low radiochemical yield.…”