Direct measurement of glyconanoparticles and lectin interactions by isothermal titration calorimetry

Abstract

Glyconanomaterials have shown high potential in applications including bioanalysis and nanomedicine. Here, a quantitative analytical technique, based on isothermal titration calorimetry, was developed to characterize the interactions between glyconanoparticles and lectins. By titrating lectins into the glyconanoparticle solution, the apparent dissociation constant, thermodynamic parameters, and the number of binding sites were derived simultaneously. For the glyconanoparticles-lectin binding pairs investigated, a 3-5 order of magnitude affinity enhancement over the free ligand-lectin interactions was observed which can be attributed to the multivalent ligand presentation on the nanoparticles. The impact of ligand density was also studied, and results showed that the affinity increased with the number of glycans on the nanoparticle.

Figure 1

ITC graphs of GNP-Man titrating with (a) Con A and (b) PNA. The experimental data (solid squares) were fit to theoretical titration curves (solid lines) using the software supplied by the ITC manufacturer.

Figure 2

ITC titration graphs of Con A with (a) GNP-Man2I, (b) GNP-Man2II, and (c) GNP-Man2III. Solid squares: experimental data, lines: fitted titration curves.

Scheme 1

Synthesis of GNPs.