title: 18F -PEG-biotin: Precursor (boroaryl-PEG-biotin) synthesis, 18F -labelling and an in-vitro assessment of its binding with Neutravidin™-trastuzumab pre-treated cells.
abstract: In terms of nuclear decay 18F is the most ideal PET nuclide but its short t(½) precludes its use for directly labelling whole antibodies due to their long blood residence times. Pre-targeted imaging using affinity systems such as Neutravidin™-biotin facilitates the application of short-lived nuclides by their attachment to biotin for imaging cell surface proteins targeted with Neutravidin™-conjugated antibodies.
  
  
  METHODS
  Boroaryl functionalised biotin was prepared with a PEG linker and radiolabelled by incubation with 18F in acidified aqueous solution. Cells expressing high (SKBr3), medium (MDA-MB-453) and low (MDA-MB-468) levels of HER-2 were pre-incubated with Neutravidin™-conjugated trastuzumab, washed, and then incubated with 18F -PEG-biotin.
  
  
  RESULTS
  The 18F -fluorination of boroaryl-PEG-biotin was much more efficient than reported for other versions of boroaryl-biotin. The novel 18F -PEG-biotin was demonstrated to bind to HER-2-expressing cells in-vitro pre-incubated with Neutravidin™-conjugated trastuzumab.
  
  
  CONCLUSIONS
  Biotin can be functionalised with boroaryl and readily 18F -radiolabelled in aqueous solution and will bind to cells pre-incubated with Neutravidin™-antibody conjugates.
authors: Biomedical Physics Building, John Mallard PET Unit, Aberdeen Biomedical Imaging Centre, School of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK. t.smith@abdn.ac.uk
authors: Tim A D
authors: TA
authors: Smith
authors: Michael
authors: M
authors: Simpson
authors: Richard
authors: R
authors: Cheyne
authors: Laurent
authors: L
authors: Trembleau