Protocatechuic acid grafted onto chitosan: Characterization and antioxidant activity

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Materials Science

Background:

• Chitosan (CS) is a biocompatible polysaccharide with potential applications in various fields.
• Protocatechuic acid (PA) is a natural phenolic compound known for its antioxidant properties.
• Grafting PA onto CS can enhance the functional properties of chitosan.

Purpose of the Study:

• To synthesize and characterize protocatechuic acid-grafted chitosan (PA-g-CS) copolymers.
• To investigate the structural, physical, and antioxidant properties of the synthesized PA-g-CS.
• To evaluate the potential of PA-g-CS as an antioxidant material.

Main Methods:

• Carbodiimide-mediated cross-linking reaction for grafting PA onto CS.
• UV-Vis spectroscopy, FTIR, 1H NMR, and 13C NMR for structural characterization.
• Scanning Electron Microscopy (SEM) for surface morphology analysis.
• Thermogravimetric Analysis (TGA) for thermal stability assessment.
• Antioxidant activity assays (reducing power and DPPH radical scavenging).

Main Results:

• Three PA-g-CS copolymers with varying grafting ratios were successfully synthesized.
• Spectroscopic analysis confirmed the successful formation of amide and ester linkages between PA and CS.
• SEM revealed a rougher surface for PA-g-CS compared to smooth CS.
• TGA indicated lower thermal stability for PA-g-CS than CS.
• PA-g-CS exhibited significantly enhanced reducing power and DPPH radical scavenging activity compared to CS.

Conclusions:

• The carbodiimide-mediated reaction effectively grafted protocatechuic acid onto chitosan.
• The synthesized PA-g-CS copolymers possess superior antioxidant capabilities compared to native chitosan.
• PA-g-CS shows promise as a functional biomaterial with enhanced antioxidant properties.