F-18 Labeled RGD Probes Based on Bioorthogonal Strain-Promoted Click Reaction for PET Imaging.

A series of fluorine-substituted monomeric and dimeric cRGD peptide derivatives, such as cRGD-ADIBOT-F (ADIBOT = azadibenzocyclooctatriazole), di-cRGD-ADIBOT-F, cRGD-PEG5-ADIBOT-F, and di-cRGD-PEG5-ADIBOT-F, were prepared by strain-promoted alkyne azide cycloaddition (SPAAC) reaction of the corresponding aza-dibenzocyclooctyne (ADIBO) substituted peptides with a fluorinated azide 3. Among these cRGD derivatives, di-cRGD-PEG5-ADIBOT-F had the highest binding affinity in a competitive binding assay compared to other derivatives and even the original cRGDyk. On the basis of the in vitro study results, di-cRGD-PEG5-ADIBOT-(18)F was prepared from a SPAAC reaction with (18)F-labeled azide and subsequent chemo-orthogonal scavenger-assisted separation without high performance liquid chromatography (HPLC) purification in 92% decay-corrected radiochemical yield (dcRCY) with high specific activity for further in vivo positron emission tomography (PET) imaging study.

Development of a simple method for protein conjugation by copper-free click reaction and its application to antibody-free Western blot analysis.

There are currently many methods available for labeling proteins in order to study their structure and function. However, the utility of these methods is hampered by low efficiency, slow reaction rates, nonbiocompatible reaction conditions, large-sized labeling groups, and the requirement of specific side chains such as cysteine or lysine. In this study, a simple and efficient method for protein labeling was developed, in which an azide-containing amino acid was introduced into a protein and conjugated to a labeling reagent by strain-promoted azide-alkyne cycloaddition (SPAAC).

F-18 labeling protocol of peptides based on chemically orthogonal strain-promoted cycloaddition under physiologically friendly reaction conditions.

We introduce the high-throughput synthesis of various (18)F-labeled peptide tracers by a straightforward (18)F-labeling protocol based on a chemo-orthogonal strain-promoted alkyne azide cycloaddition (SPAAC) using aza-dibenzocyclootyne-substituted peptides as precursors with (18)F-azide synthon to develop peptide based positron emission tomography (PET) molecular imaging probes. The SPAAC reaction and subsequent chemo-orthogonal purification reaction with azide resin proceeded quickly and selectively under physiologically friendly reaction conditions (i.e.

Synthesis of N₄'-[¹⁸F]fluoroalkylated ciprofloxacin as a potential bacterial infection imaging agent for PET study.

Syntheses and evaluation of fluoroalkylated ciprofloxacin analogues are described. Among these analogues, N₄'-3-fluoropropylciprofloxacin (16) showed the most efficient antibacterial activity against E. coli strains (DH5α and TOP10) and a high binding affinity for DNA gyrase of bacteria.