Agar and Chitosan Hydrogels' Design for Metal-Uptaking Treatments

Area of Science:

• Materials Science
• Chemistry
• Cultural Heritage Conservation

Background:

• Natural polymers like agar and chitosan are increasingly used as carriers for active agents in cultural heritage.
• Chitosan, in particular, shows potential for metal-binding applications.

Purpose of the Study:

• To assess agar and chitosan as natural gel carriers for active agents.
• To evaluate the compatibility of deferoxamine with these hydrogels.
• To investigate the silver-complexing ability of chitosan formulation (CS-ItA-LCys).

Main Methods:

• Fourier-transformed infrared spectroscopy (FTIR) for molecular structure analysis.
• Rheological measurements for mechanical properties.
• Cryo-Scanning Electron Microscopy (cryo-SEM) for microstructure investigation.
• FT-Raman spectroscopy for silver ion complexation analysis.

Main Results:

• Both agar and chitosan hydrogels exhibited distinct microstructures and mechanical behaviors (chitosan: thick membrane, agar: brittle).
• Deferoxamine addition did not significantly alter the rheological or molecular properties of either hydrogel.
• Chitosan formulation (CS-ItA-LCys) demonstrated intrinsic silver-complexing ability, evidenced by Ag-S and Ag-O bonds.

Conclusions:

• Agar and chitosan are suitable and reliable natural gel systems for delivering bio-based active agents in conservation.
• The chitosan formulation CS-ItA-LCys is a promising material for the complexation of soluble silver in cultural heritage treatments.