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Surface grafted chitosan gels. Part II. Gel formation and characterization
Chao Liu1, Esben Thormann, Per M Claesson
1School of Chemical Science and Engineering, Department of Chemistry, Surface and Corrosion Science, KTH Royal Institute of Technology , Drottning Kristinas väg 51, SE-100 44 Stockholm, Sweden.
Langmuir : the ACS Journal of Surfaces and Colloids
|July 10, 2014
Summary
This study developed stable, responsive chitosan-based hydrogels using a layer-by-layer approach. Cross-linking density controls gel responsiveness and stability, offering tunable biomaterial properties.
Area of Science:
- Biomaterials Science
- Polymer Chemistry
- Surface Science
Background:
- Responsive hydrogels are crucial biomaterials due to their biocompatibility and degradability.
- Chitosan-based hydrogels offer a promising platform for advanced applications.
- Controlling hydrogel properties like stability and responsiveness is key for their utility.
Purpose of the Study:
- To develop a novel method for creating surface-grafted chitosan/poly(acrylic acid) hydrogels.
- To investigate the effect of cross-linking density on gel stability and pH responsiveness.
- To gain molecular insights into the cross-linking mechanism and hydrogel behavior.
Main Methods:
- Layer-by-layer assembly of chitosan and poly(acrylic acid) on silica.
- Chemical cross-linking of chitosan using glutaraldehyde.
- In situ monitoring of cross-linking using total internal reflection Raman (TIRR) spectroscopy.
- Ex situ analysis using Fourier transform infrared (FTIR) spectroscopy.
- Characterization of pH responsiveness using quartz crystal microbalance with dissipation (QCM-D) and TIRR.
Main Results:
- A stable, surface-grafted cross-linked gel was successfully fabricated.
- Cross-linking density was quantified and correlated with poly(acrylic acid) content.
- Higher cross-linking led to enhanced stability but reduced pH responsiveness.
- Lower cross-linking resulted in greater pH responsiveness, with some irreversible changes observed initially.
- Two distinct pKa values were identified for chitosan and poly(acrylic acid) within the hydrogel structure.
Conclusions:
- Chemical cross-linking is an effective strategy to enhance the stability of chitosan-based hydrogels.
- The cross-linking density critically influences the pH-responsive behavior of these biomaterials.
- TIRR spectroscopy provides valuable molecular-level understanding of hydrogel formation and response.
- These tunable chitosan-based hydrogels show potential for applications requiring controlled swelling and release.
