Responsive complex capsules prepared with polymerization of dopamine, hydrogen-bonding assembly, and catechol...

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Layer-by-layer (LbL) assembly is a versatile technique for fabricating multilayered structures.
• Polydopamine (PDA) has shown promise in creating robust and functional coatings.
• Hydrogen bonding plays a crucial role in the assembly and responsiveness of nanostructures.

Purpose of the Study:

• To develop novel complex capsules by integrating polydopamine polymerization with hydrogen-bonding LbL assembly.
• To investigate the pH-responsive behavior and swelling-shrinking characteristics of the fabricated capsules.
• To evaluate the potential of these capsules for controlled drug loading and release applications.

Main Methods:

• Fabrication of complex capsules using dopamine polymerization and LbL assembly of dopamine-modified poly(acrylic acid) (PAA-dopa) and poly(vinylpyrrolidone) (PVPON).
• Cross-linking of the PDA(PAA-dopa/PVPON)n shell via catechol group reactions.
• Assessment of pH-responsive swelling-shrinking behavior by monitoring volume changes at different pH values.
• Evaluation of Rhodamine 6G (R6G) loading and release kinetics as a function of pH.

Main Results:

• Successfully fabricated soft and flexible complex capsules with a PDA(PAA-dopa/PVPON)n shell.
• Demonstrated significant pH-responsive swelling-shrinking behavior, with a volume swelling ratio of 1.34 for PDA(PAA-dopa/PVPON)1 capsules from pH 2.0 to 8.5.
• Exhibited controlled loading and release of Rhodamine 6G (R6G) in response to pH variations.

Conclusions:

• The developed complex capsules possess tunable pH-responsive properties due to hydrogen bond dynamics.
• The soft and flexible nature of the capsules, combined with their pH responsiveness, makes them suitable for drug delivery systems.
• These findings highlight the potential of combining polydopamine chemistry with LbL assembly for advanced functional materials.