{Reference Type}: Journal Article {Title}: Expanding the Applicability of the Metal Labeling of Biomolecules by the RIKEN Click Reaction: A Case Study with Gallium-68 Positron Emission Tomography. {Author}: Nakamoto Y;Pradipta AR;Mukai H;Zouda M;Watanabe Y;Kurbangalieva A;Ahmadi P;Manabe Y;Fukase K;Tanaka K; {Journal}: Chembiochem {Volume}: 19 {Issue}: 19 {Year}: 10 2018 4 {Factor}: 3.461 {DOI}: 10.1002/cbic.201800335 {Abstract}: Radiolabeled biomolecules with short half-life times are of increasing importance for positron emission tomography (PET) imaging studies. Herein, we demonstrate an improved and generalized method for synthesizing a [radiometal]-unsaturated aldehyde as a lysine-labeling probe that can be easily conjugated into various biomolecules through the RIKEN click reaction. As a case study, 68 Ga-PET imaging of U87MG xenografted mice is demonstrated by using the 68 Ga-DOTA-RGDyK peptide, which is selective to αV β3 integrins.