Controlled drug release from the aggregation-disaggregation behavior of pH-responsive microgels

Area of Science:

• Polymer Chemistry
• Materials Science
• Biotechnology

Background:

• Poly(N-isopropylacrylamide) (pNIPAm) microgels are stimuli-responsive materials.
• pH-responsive microgels offer tunable properties for various applications.
• Controlled drug delivery systems are crucial for therapeutic advancements.

Purpose of the Study:

• To synthesize and characterize two independent sets of pH-responsive microgels.
• To investigate the aggregation and disaggregation behavior of these microgels in response to pH changes.
• To demonstrate the potential of these microgels for controlled/triggered drug delivery.

Main Methods:

• Microgels synthesized via copolymerization of pNIPAm with acrylic acid or N-[3-(dimethylamino)propyl]methacrylamide.
• pH-dependent charge characterization of individual microgel sets.
• Observation of microgel aggregation and disaggregation in mixed solutions at varying pH.
• Loading and release studies using methylene blue as a model drug.

Main Results:

• Microgels copolymerized with acrylic acid are negatively charged above pH 4.25.
• Microgels copolymerized with N-[3-(dimethylamino)propyl]methacrylamide are positively charged below pH 8.4.
• Microgel aggregates form when both sets are charged in solution; disaggregation occurs when one set neutralizes.
• Successful loading and release of methylene blue were achieved using the aggregation-disaggregation mechanism.

Conclusions:

• A novel pH-responsive microgel system was developed based on pNIPAm copolymers.
• The tunable aggregation-disaggregation behavior enables controlled loading and release of model drugs.
• This system demonstrates the potential of pNIPAm-based microgels for advanced drug delivery applications.