Chemical Modification of Alginate for Controlled Oral Drug Delivery

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Drug Delivery Systems

Background:

• Alginate hydrogels are widely used but often lack precise pH responsiveness for targeted delivery.
• Developing pH-sensitive materials is crucial for controlled release in specific physiological environments, like the gastrointestinal tract.

Purpose of the Study:

• To chemically modify alginate to create hydrogels with neutral-basic pH sensitivity.
• To develop alginate-based hydrogel vehicles for targeted payload delivery under physiological conditions.
• To investigate methods for controlling the degradation rate of alginate hydrogels.

Main Methods:

• Two chemical modification methods were employed: direct amide bond formation and reductive amination of oxidized alginate.
• Nuclear magnetic resonance (NMR) spectroscopy, including 2D diffusion-ordered spectroscopy, was used to confirm chemical bonding and incorporation.
• Hydrogel stability and disintegration were tested across a range of pH conditions (acidic, neutral, and basic).

Main Results:

• Both modification methods yielded alginate hydrogels sensitive to neutral-basic pH.
• Hydrogels exhibited complete stability at acidic pH and rapid disintegration (minutes to hours) at neutral-basic pH.
• The rate of hydrogel disintegration correlated with the degree of oxidation in the second modification method.

Conclusions:

• Chemically modified alginate hydrogels offer tunable, pH-dependent release profiles.
• These novel hydrogels are suitable for targeted delivery applications within the gastrointestinal tract.
• The developed methods provide control over hydrogel degradation rates for enhanced drug delivery efficacy.