Rapidly labeling antibodies with luminescence

Labelled cells10 June 2016:

CNBP and Macquarie University researchers have successfully developed a novel indirect universal detection reagent that rapidly labels antibodies with luminescence within seconds and without the need for any complicated bioconjugation procedures. The reagent, reported in the journal ‘Scientific Reports’, can be used to directly label antibodies for several time-gated luminescence applications, e.g., bioimaging, cell labeling and detection, and flow cytometry.

The work was co-authored by CNBP researchers Dr Andrew Care and Dr Nima Sayyadi and led by CNBP Associate Investigator Dr Anwar Sunna.

Pictured (top left) – giardia cyst cells labeled with europium chelate.

Publication title: A Novel Universal Detection Agent for Time-Gated Luminescence Bioimaging

Authors: Nima Sayyadi and Andrew Care ( first co-authors), Russell E. Connally, Andrew C. Try, Peter L. Bergquist and Anwar Sunna

Luminescent lanthanide chelates have been used to label antibodies in time-gated luminescence (TGL) bioimaging. However, it is a challenging task to label directly an antibody with lanthanide-binding ligands and achieve control of the target ligand/protein ratios whilst ensuring that affinity and avidity of the antibody remain uncompromised. We report the development of a new indirect detection reagent to label antibodies with detectable luminescence that circumvents this problem by labelling available lysine residues in the linker portion of the recombinant fusion protein Linker-Protein G (LPG). Succinimide-activated lanthanide chelating ligands were attached to lysine residues in LPG and Protein G (without Linker) and the resulting Luminescence-Activating (LA-) conjugates were compared for total incorporation and conjugation efficiency. A higher and more efficient incorporation of ligands at three different molar ratios was observed for LPG and this effect was attributed to the presence of eight readily available lysine residues in the linker region of LPG. These Luminescence-Activating (LA-) complexes were subsequently shown to impart luminescence (upon formation of europium(III) complexes) to cell-specific antibodies within seconds and without the need for any complicated bioconjugation procedures. The potential of this technology was demonstrated by direct labelling of Giardia cysts and Cryptosporidium oocysts in TGL bioimaging.

The paper is available online.