Alginate esters via chemoselective carboxyl group modification

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Carbohydrate Chemistry

Background:

• Alginates are natural polysaccharides with diverse applications.
• Existing methods for modifying alginate carboxyl groups often use aqueous chemistries.
• Homogeneous dissolution of alginates is challenging, limiting synthetic approaches.

Purpose of the Study:

• To develop a novel, efficient method for synthesizing carboxyl-modified alginate esters.
• To utilize tetrabutylammonium fluoride (TBAF)-based solvent systems for alginate modification.
• To demonstrate the utility of these alginate esters in drug delivery applications.

Main Methods:

• Homogeneous dissolution of alginate using tetrabutylammonium (TBA)-alginate.
• Synthesis of alginate esters (benzyl, butyl, ethyl, methyl) using TBAF-based solvent systems and alkyl halides.
• Characterization of synthesized alginate derivatives, including solubility and saponification for regioselectivity.
• Formation of solid dispersions with naringenin to assess enhanced aqueous solubility.

Main Results:

• Successfully synthesized various carboxyl-modified alginate esters.
• Demonstrated complete regioselectivity for carboxylate groups over hydroxyl groups during alkylation.
• Newly synthesized alginate esters showed solubility in polar aprotic solvents without TBAF.
• Alginate esters effectively enhanced the aqueous solubility of naringenin via solid dispersions.

Conclusions:

• TBAF-based solvent systems provide an effective medium for synthesizing carboxyl-modified alginate esters.
• The synthesized alginate esters are regioselective and exhibit improved solubility properties.
• These novel alginate derivatives show promise for improving the aqueous solubility of poorly soluble compounds, such as flavonoids, for pharmaceutical applications.