page_title: Acetalated dextran
section_title: Properties
hierarchical_section_title: Acetalated dextran / Properties
caption_attribution_description: English: Cyclic and acyclic acetals on acetalated dextran which degrades to dextran, acetone, and ethanol.
context_page_description: Acetalated dextran is a biodegradable polymer based on dextran that has acetal modified hydroxyl groups. After synthesis, the hydrophilic polysaccharide dextran is rendered insoluble in water, but soluble in organic solvents. This allows it to be processed in the same manner as many polyesters, like poly, through processes like solvent evaporation and emulsion. Acetalated dextran is structurally different from acetylated dextran.
context_section_description: During the synthesis of acetalated dextran both acyclic and cyclic acetals are formed. The acyclic acetals degrade into an acetone and an alcohol, whereas cyclic acetals degrade into acetone. The ratio of cyclic to acyclic acetals varies with reaction time since acyclic acetals are kinetically favored and cyclic acetals are the thermodynamically favored. This unique formation of cyclic and acyclic acetals leads to varying degradation time because the two acetal groups hydrolyze at different rates. Acetalated dextran's degradation time can vary from hours to a month or more at pH 7.2. Also, acetalated dextran is unique because it is acid sensitive. Therefore, at lower pH acetalated dextran degrades more rapidly, which results in a polymer that degrades approximately two logs faster at pH 5 compared to pH 7. The acid-sensitivity of Ac-DEX has illustrated, when formulated into nanoparticles encapsulating a protein antigen, more efficient presentation of antigen to both MHC class I and MHC class II, over other non-acid sensitive polymers like PLGA and non degradable materials like gold nanoparticles.
caption: Cyclic and acyclic acetals on acetalated dextran which degrades to dextran, acetone, and ethanol.
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