Overcoming the aggregation problem : a new type of fluorescent ligand for ConA-based glucose sensing

Cummins, Brian M. and Li, Mingchien and Locke, Andrea K. and Birch, David J.S. and Vigh, Gyula and Cote, Gerard L. (2015) Overcoming the aggregation problem : a new type of fluorescent ligand for ConA-based glucose sensing. Biosensors and Bioelectronics, 63. pp. 53-60. ISSN 0956-5663

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    Competitive binding assays based on the lectin Concanavalin A (ConA) have displayed significant potential to serve in continuous glucose monitoring applications. However, to date, this type of fluorescent, affinity-based assay has yet to show the stable, glucose predictive capabilities that are required for such an application. This instability has been associated with the extensive crosslinking between traditionally-used fluorescent ligands (presenting multiple low-affinity moieties) and ConA (presenting multiple binding sites) in free solution. The work herein introduces the design and synthesis of a new type of fluorescent ligand that can avoid this aggregation and allow the assay to be sensitive across the physiologically relevant glucose concentration range. This fluorescent ligand (APTS-MT) presents a single high-affinity trimannose moiety that is recognized by ConA’s full binding site and a fluorophore that can effectively track the ligand’s equilibrium binding via fluorescent anisotropy. This is confirmed by comparing its measured fluorescent lifetime to experimentally-determined rotational correlation lifetimes of the free and bound populations. Using an assay comprised of 200 nM APTS-MT and 1 μM ConA, the fluorescence anisotropy capably tracks the concentration of monosaccharides that are known to bind to ConA’s primary binding site, and the assay displays a MARD of 6.5% across physiologically relevant glucose concentrations. Ultimately, this rationally-designed fluorescent ligand can facilitate the realization of the full potential of ConA-based glucose sensing assays and provide the basis for a new set of competing ligands to be paired with ConA.

    ORCID iDs

    Cummins, Brian M., Li, Mingchien, Locke, Andrea K., Birch, David J.S. ORCID logoORCID: https://orcid.org/0000-0001-6400-1270, Vigh, Gyula and Cote, Gerard L.;