A bioorthogonal time-resolved luminogenic probe for metabolic labelling and imaging of glycans

The use of bioorthogonal fluorogenic probes is superior to labelling and imaging of biomolecules in live cells and organisms, although overcoming the limitation of autofluorescence is still a challenge for current probes to achieve high illumination resolution of the target of interest. We herein demonstrate a functionalized terbium complex Tb-1 that is stable and biocompatible to enable bioorthogonal ligation with engineered cell-surface glycans for providing responsive luminescence. A luminescence resonance energy transfer (LRET) quencher with bioorthogonal properties is strategically incorporated into a tripodal terbium complex with low toxicity, which can undergo a click-cycloaddition reaction with a cyclooctene to completely change the electronic structure of the quencher, resulting in a much less efficient LRET but a 5-fold enhancement in the long-lived terbium emission intensity. This work therefore establishes a time-resolved platform that enables labelling and imaging of the biomolecules of interest.