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Transport Properties of Ibuprofen Encapsulated in Cyclodextrin Nanosponge Hydrogels: A Proton HR-MAS NMR Spectroscopy Study
Published on: August 15, 2016
Hydration and dynamic behavior of cyclodextrins in aqueous solution
Toshiyuki Shikata1, Rintaro Takahashi, Yuichi Satokawa
1Department of Macromolecular Science, Osaka University, Toyonaka, Osaka 560-0043, Japan. shikata@chem.sci.osaka-u.ac.jp
The Journal of Physical Chemistry. B
|October 5, 2007
Summary
Chemically modified cyclodextrins (CDs) exhibit altered hydration dynamics and increased solubility in water. Dielectric relaxation measurements reveal how modifications affect water molecule interactions and CD rotational relaxation.
Area of Science:
- Physical Chemistry
- Supramolecular Chemistry
Background:
- Cyclodextrins (CDs) are cyclic oligosaccharides with unique host-guest properties.
- Understanding the hydration of CDs is crucial for their applications in drug delivery and material science.
- Chemical modification of CDs can alter their physicochemical properties, including solubility and binding affinity.
Purpose of the Study:
- To investigate the hydration state and dynamics of plain and chemically modified cyclodextrins (CDs).
- To elucidate the relationship between chemical modification, hydration number, and solubility of CDs.
- To analyze the rotational relaxation processes of water molecules and CDs in aqueous solutions.
Main Methods:
- Dielectric relaxation measurements were performed on plain and modified CDs in aqueous solution at 25°C.
- Measurements covered a wide frequency range up to 20 GHz.
- Dielectric relaxation spectra were analyzed by decomposing them into distinct relaxation modes.
Main Results:
- Two major relaxation modes (fast and medium) were identified, attributed to bulk water and water molecules hydrated to CDs, respectively.
- A minor, slow relaxation mode was assigned to the overall rotational relaxation of CDs.
- Hydration numbers of CDs were found to be dependent on the number of hydroxyl (OH) groups, increasing with methylation or other modifications.
- Increased hydration numbers correlated with enhanced solubilities of chemically modified CDs compared to plain CDs.
Conclusions:
- Chemical modifications significantly influence the hydration dynamics and state of cyclodextrins in aqueous solutions.
- The number of hydroxyl groups is a key factor determining CD hydration and solubility.
- Dielectric relaxation spectroscopy provides valuable insights into the molecular interactions and dynamics of cyclodextrins and their associated water molecules.
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