title: Radiolabeling of RGD peptide and preliminary biological evaluation in mice bearing U87MG tumors.
abstract: 2-[(18)F]Fluoroethyl azide ([(18)F]FEA) and terminal alkynyl modified propioloyl RGDfK were selected in this study. [(18)F]FEA was prepared by nucleophilic radiofluorination of 2-azidoethyl 4-toluenesulfonate with radiochemical yield of 71 ± 4% (n = 5, decay-corrected). We assessed the various conditions of the CuAAC reaction between [(18)F]FEA and propioloyl RGDfK, which included peptide concentration, reaction time, temperature and catalyst dosage. The (18)F-labeled-RGD peptide ([(18)F]F-RGDfK) could be obtained in 60 min by a two-step radiochemical synthesis route, with total radiochemical yield of 60 ± 2% (n = 3, decay-corrected) through click chemistry. [(18)F]F-RGDfK showed high stability in phosphate buffered saline and new-born calf serum. Micro-PET imaging at 1 h post injection of [(18)F]F-RGDfK showed medium concentration of radioactivity in tumors while much decreased concentration in tumors in the blocking group. These results showed that [(18)F]F-RGDfK obtained by click chemistry maintained the affinity and specificity of the RGDfK peptide to integrin α(v)β(3). This study provided useful information for peptide radiofluorination by using click chemistry.
authors.affiliation: Shanghai Institute of Applied Physics, Chinese Academy of Sciences, PO Box 800-204, Shanghai 201800, China.
authors.forename: Jianbo
authors.initials: J
authors.lastname: Li
authors.forename: Lingli
authors.initials: L
authors.lastname: Shi
authors.forename: Lina
authors.initials: L
authors.lastname: Jia
authors.forename: Dawei
authors.initials: D
authors.lastname: Jiang
authors.forename: Wei
authors.initials: W
authors.lastname: Zhou
authors.forename: Weiqing
authors.initials: W
authors.lastname: Hu
authors.forename: Yujin
authors.initials: Y
authors.lastname: Qi
authors.forename: Lan
authors.initials: L
authors.lastname: Zhang
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D005462:Fluorine Radioisotopes / Q000493:pharmacokinetics; D006801:Humans; D051379:Mice; D008815:Mice, Inbred Strains; D009374:Neoplasms, Experimental / Q000175:diagnosis*; D009842:Oligopeptides / Q000737:chemistry / Q000493:pharmacokinetics; D014018:Tissue Distribution
chemical_list: D005462:Fluorine Radioisotopes; D009842:Oligopeptides; C047981:arginyl-glycyl-aspartic acid