# Facile Automated Radiosynthesis of an Arginine Selective Bioconjugation Reagent 4‑[18F]Fluorophenylglyoxal for Developing Protein-Based PET Molecular Probes

## TL;DR

This paper describes a new method to automate the production of a compound used to label proteins for PET imaging, which is selective for arginine and stable in biological conditions.

## Contribution

The paper introduces an automated radiosynthesis method for [18F]FPG, a novel arginine-selective reagent for protein labeling.

## Key findings

- [18F]FPG was synthesized with 27% radiochemical yield in 56 minutes using a one-pot process.
- [18F]FPG-IL4 showed >95% stability in PBS and human serum and specific uptake by activated Jurkat cells.
- In vivo studies in mice demonstrated biodistribution and pharmacokinetics of [18F]FPG-IL4 via PET imaging.

## Abstract

4-[18F]­Fluorophenylglyoxal ([18F]­FPG) is
a novel arginine selective bioconjugation reagent for native protein 18F-labeling. Here, we report the automated radiosynthesis
of [18F]­FPG on a Scintomics GRP module. The radiochemical
preparation was performed in a one-pot, two-step process using a DMSO-resistant
cassette system. A cartridge-based purification method was developed
to purify [18F]­FPG without HPLC. The [18F]­FPG
was prepared in nondecay corrected (n.d.c.) radiochemical yields (RCYs)
of 27 ± 2% (n = 5) in 56 min from the end of
the bombardment until formulation. The molar activities of [18F]­FPG were 147 ± 70 GBq/μmol (n = 5).
The 4-[18F]­FPG was then conjugated with interleukin-4 (IL-4)
in n.d.c. 26 ± 2% RCYs (n = 3) from [18F]­FPG with molar activities of 24 ± 4 GBq/μmol (n = 3). [18F]­FPG-IL4 exhibited >95% stability
in either PBS (4 h) or human serum (2 h) in vitro. [18F]­FPG-IL4
showed specific uptake by the PHA-activated Jurkat cells. The in vivo
biodistribution and pharmacokinetics of [18F]­FPG-IL4 were
evaluated in healthy Balb/c mice with PET imaging.