This work is aimed at synthesizing an 18F-labelled folate derivative that can be used as folate-receptorinduced tumor PET imaging agent.Under the optimal reaction and testing specification formulated during the cold-labeling experiments

18F labeling of folic acid was achieved in three steps of 18F pre-labeling

bromination and esterification.The receptor binding property of the newly-synthesized folate radio-derivative was studied through β-lactoglobulin binding test.Tumor-bearing nude mice injected with the new compound were used to study whether the derivative can accumulate within tumor issue.Preliminary studies in vitro and in vivo showed that this new PET agent still possessed receptor binding qualities of folic acid.18F-flurophenethyl folate remained good affinity and specificity with β-lactoglobulin.Accumulation of activities in tumor tissues was found in tumor-bearing nude mice.A new folate receptor ligand:18F-flurophenethyl folate was synthesized

with high yield and good stability.Since the pre-labeling method was used

the fluorine labeling was not directly imposed upon folic acid.In this way

the structure destruction

which happens in high temperature reaction of folic acid

can be avoided.The synthesized folate derivative remained the binding structural quality of folic acid and could bind with the folate-binding protein:β-lactoglobulin.Through the folate receptors located on tumor tissues

18F-flurophenethyl folate accumulated in the tumor tissue

exhibiting its potential as a tumor PET imaging agent.