Dramatically Increased Binding Constant of Water-Soluble Cyclodextrin Hyperbranched Polymers: Explored with Diffusion...

Area of Science:

• Supramolecular chemistry
• Polymer science
• Drug delivery systems

Background:

• Cyclodextrins (CDs) are widely used in drug delivery due to their ability to form host-guest complexes.
• Enhancing the binding affinity of CDs to guest molecules is crucial for improving drug loading and efficacy.
• The development of novel CD-based materials is essential for advancing drug delivery technologies.

Purpose of the Study:

• To investigate the effect of polymerizing cyclodextrin (CD) with epichlorohydrin (ECH) on the binding affinity to vanillin.
• To quantify the binding constant of the novel CD-ECH polymers using advanced spectroscopic techniques.
• To explore the potential of these CD-ECH polymers in enhancing drug loading for drug delivery applications.

Main Methods:

• Synthesis of cyclodextrin-epichlorohydrin (CD-ECH) polymers.
• Determination of binding constants using diffusion ordered spectroscopy (DOSY)-¹H NMR.
• Analysis of the influence of ECH content on binding affinity.

Main Results:

• Polymerization of CD with ECH increased the binding constant to vanillin by approximately 100-fold (from 55 to 8.4 × 10³ M⁻¹).
• The binding constant showed a positive correlation with the ECH content in the CD-ECH polymers.
• ECH polymers without CDs exhibited no significant binding affinity for vanillin.

Conclusions:

• CD-ECH polymers demonstrate significantly enhanced binding affinity for vanillin compared to native CDs.
• The hydrophobic network of ECH outside the CD cavity plays a crucial role in enhancing guest binding.
• The improved binding capacity of CD-ECH polymers offers a promising strategy for increasing drug loading in drug delivery systems.