Preparation and Evaluation of Fluorine-18-Labeled Insulin as a Molecular Imaging Probe for Studying Insulin Receptor Expression in Tumors

A convenient emulsion-based labeling method was used to synthesize fluorine-18-labeled insulin specifically B(1)-(4-[(18)F]fluorobenzoyl)insulin ((18)F-4b) in 6% overall radiochemical yield in 240 min. In vitro screening in MCF7 breast cancer cells demonstrated that the nonradioactive analogue (19)F-4a effectively competed with (125)I-insulin for the insulin receptor (IC50 = 10.6 nM) comparable to that for insulin (IC50 = 7.4 nM). (18)F-4b was …