Fluorinated Proteins as Potential ¹⁹F Magnetic Resonance Imaging and Spectroscopy Agents

Fluorinated proteins have been synthesized and characterized as potential in vivo ¹⁹F magnetic resonance imaging (MRI) and spectroscopy (MRS) agents. Proteins labeled with fluorine include bovine serum albumin, γ-globulin, and purified immunoglobulin (IgG). The amino groups in proteins were selectively trifluoroacetylated using S-ethyl trifluorothioacetate to synthesize fluorinated proteins (TFA-protein; 1–3). In another approach, trifluoroacetamidosuccinic anhydride has been used to prepare corresponding fluorinated derivatives of proteins (TFASA-protein; 4–6). The fluorinated proteins have been purified by exhaustive dialysis and isolated in good yields (55–76%). The fluorinated proteins exhibit useful NMR characteristics and the biocompatibility for in vivo studies. The initial investigations demonstrate the potential of these new fluorinated proteins as in vivo MRI/MRS probes.