Affinity capillary electrophoretic studies of complexation between dextrin oligomers and polyiodides

Area of Science:

• Analytical Chemistry
• Carbohydrate Chemistry
• Supramolecular Chemistry

Background:

• Dextrin-polyiodide complexation is crucial in various applications, but understanding interactions at the individual molecule level has been challenging.
• Previous bulk measurements limited insights into the contribution of specific dextrin oligomers to complex formation.

Purpose of the Study:

• To investigate dextrin-polyiodide complexation using capillary electrophoresis (CE) for single oligomer analysis.
• To determine the influence of dextrin degree of polymerization (DP) and solution parameters on complexation dynamics.

Main Methods:

• Capillary electrophoresis (CE) with fluorescently labeled dextrins.
• Analysis of peak migration times and shapes to detect complex formation.
• UV-Vis diode-array spectroscopy for differential complexation confirmation.
• 13C-Nuclear Magnetic Resonance (NMR) spectroscopy for structural validation.

Main Results:

• CE achieved baseline separation of dextrin oligomers, allowing observation of individual contributions to polyiodide complexation.
• Complex formation was evident through changes in migration times and peak shapes.
• Dextrin DP and the solution's I2/I- ratio significantly impacted complexation nature.
• CE iodine affinity separation and subsequent spectroscopy confirmed differential complexation based on DP.

Conclusions:

• CE provides a powerful platform for dissecting molecular interactions in dextrin-polyiodide systems.
• The degree of polymerization of dextrins is a critical factor in their binding affinity with polyiodides.
• Solution conditions, including pH and ionic strength, modulate the complexation behavior.