β-Cyclodextrin polymer binding to DNA: Modulating the physicochemical parameters

Area of Science:

• Biophysics
• Polymer Chemistry
• Molecular Biology

Background:

• Cyclodextrins (CDs) are known for their ability to encapsulate hydrophobic molecules.
• Understanding host-guest interactions is crucial for drug delivery and biomaterial design.
• The interaction between cyclodextrins and DNA is of interest for modulating DNA properties.

Purpose of the Study:

• To investigate the interaction between a β-cyclodextrin polymer (poly-β-CD) and λ-DNA.
• To characterize the changes in DNA's mechanical properties upon interaction with poly-β-CD.
• To determine the physical chemistry of the poly-β-CD-DNA interaction.

Main Methods:

• Synthesis of poly-β-CD from β-cyclodextrin and epichlorohydrin.
• Utilized optical tweezers to measure changes in DNA mechanical properties (persistence length, contour length).
• Applied a quenched-disorder statistical model to analyze interaction thermodynamics.

Main Results:

• Poly-β-CD did not alter the contour length of DNA up to 300 μM concentration.
• Significant changes in DNA persistence length indicated two binding modes of poly-β-CD.
• Polymeric β-CD showed a binding constant three orders of magnitude higher than monomeric β-CD.

Conclusions:

• Polymerization of β-cyclodextrin dramatically increases its binding affinity to DNA.
• Poly-β-CD exhibits concentration-dependent binding modes with DNA.
• The findings suggest that poly-β-CD can be used to modulate DNA-cyclodextrin interactions for potential applications.