Acetal-derivatized dextran: an acid-responsive biodegradable material for therapeutic applications

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Drug Delivery Systems

Background:

• Dextran is a biocompatible, water-soluble polysaccharide.
• Current drug delivery systems face challenges in controlled release and cargo loading.
• Acid-sensitive materials are desirable for targeted drug release in specific physiological environments.

Purpose of the Study:

• To develop a novel acid-sensitive dextran-based microparticle system.
• To evaluate the pH-dependent degradation and cargo release kinetics.
• To assess the potential of these microparticles in drug delivery and vaccine applications.

Main Methods:

• Dextran modification with acetal moieties to achieve water insolubility and organic solvent solubility.
• Fabrication of acid-sensitive microparticles using modified dextran.
• Loading of hydrophobic and hydrophilic cargoes via single and double emulsion techniques.
• Evaluation of FITC-dextran release at different pH values (5.0 and 7.4) at 37°C.
• Assessment of ovalbumin (OVA) loaded microparticles in a model vaccine application for CD8+ T-cell response.
• In vitro cytotoxicity assays to determine biocompatibility.

Main Results:

• Modified dextran enabled facile preparation of water-insoluble, organic-solvent-soluble microparticles.
• Microparticles exhibited pH-dependent degradation, with faster release at acidic pH (half-life of 10 h at pH 5.0) compared to neutral pH (half-life of ~15 days at pH 7.4).
• Both hydrophobic and hydrophilic cargoes were successfully loaded using emulsion techniques.
• OVA-loaded microparticles significantly enhanced the presentation of OVA-derived peptides to CD8+ T-cells (16-fold increase).
• Preliminary in vitro assays indicated the modified dextran derivative is non-toxic.

Conclusions:

• Acetal-modified dextran provides a versatile platform for creating pH-sensitive microparticles.
• These microparticles offer controlled degradation and efficient cargo loading for drug delivery.
• The system demonstrates significant potential in enhancing vaccine efficacy and warrants further investigation for therapeutic applications.