Formulation of Next-Generation Multicompartment Microcapsules by Reversible Electrostatic Attraction.

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Combining multiple active substances in one carrier faces limitations like solubility and phase separation.
• Hierarchical delivery systems offer potential solutions to these challenges.

Purpose of the Study:

• To design and fabricate a novel pH-responsive hierarchical capsule@capsule system.
• To overcome limitations in co-delivery of active substances using nanocapsule assembly on microcapsules.

Main Methods:

• Synthesized melamine-formaldehyde (MF) microcapsules with a negative surface charge.
• Coated MF microcapsules with a novel MF-polyethyleneimine (PEI) copolymer to achieve a positive surface charge (+28 mV).
• Electrostatic assembly of negatively charged poly-l-lactide (PLLA, -19 mV) and poly-(lactide-co-glycolide) (PLGA, -56 mV) nanocapsules onto the modified microcapsule surface.

Main Results:

• Achieved electrostatic assembly of nanocapsules on microcapsule surfaces.
• Observed partial surface coverage with PLLA nanocapsules and full coverage with PLGA nanocapsules at pH 7.
• Demonstrated pH-responsive adsorption and desorption of nanocapsules at pH 7 and pH 3.

Conclusions:

• Successfully developed a pH-responsive hierarchical capsule@capsule system using electrostatic assembly.
• The novel coating strategy enables the controlled loading of nanocapsules onto microcapsules.
• This system shows potential for overcoming challenges in co-delivery systems.