A novel sialidase-activatable fluorescence probe with improved stability for the sensitive detection of sialidase

Sialidases catalyse the hydrolysis of terminal sialic acid residues of various glycoconjugates and visualising sialidase activity is important for understanding its function in the biological and pathological context. Upon developing a novel fluorescence probe for sialidase with improved fluorescence characteristics based on our previously reported fluorophore, HMRef, an inherent instability of sialic acid conjugates was found to both reduce selectivity and sensitivity. We aimed at increasing the stability of the probes by incorporating a self-immolative spacer with a higher pK_a between the sialic acid residue and HMRef to develop HMRef-S-Neu5Ac, which shows superior stability allowing for the specific detection of sialidase.