# Polyelectrolyte Microcapsule-Assembled Colloidosomes: A Novel Strategy for the Encapsulation of Hydrophobic Substances

## TL;DR

This paper introduces a new method using polyelectrolyte microcapsules to better encapsulate hydrophobic substances, offering improved stability and potential for drug delivery and other applications.

## Contribution

A novel strategy for encapsulating hydrophobic substances using colloidosomes assembled from polyelectrolyte microcapsules.

## Key findings

- MnCO3-based PMCs showed 3.5-fold greater stability than CaCO3-based PMCs due to enhanced inter-capsule interactions.
- Colloidosomes retained structural integrity for up to 30 minutes and 5% post-water evaporation.
- PMC-based colloidosomes offer semi-permeability, tunable shell properties, and stimuli-responsive behavior.

## Abstract

The encapsulation of hydrophobic substances remains a significant challenge due to limitations such as low loading efficiency, leakage, and poor distribution within microcapsules. This study introduces a novel strategy utilizing colloidosomes assembled from polyelectrolyte microcapsules (PMCs). PMCs were fabricated via layer-by-layer (LbL) assembly on manganese carbonate (MnCO3) or calcium carbonate (CaCO3) cores, followed by core dissolution. A solvent gradient replacement method was employed to substitute the internal aqueous phase of PMCs with kerosene, enabling the formation of colloidosomes through self-assembly upon resuspension in water. Comparative analysis revealed that MnCO3-based PMCs with smaller diameters (2.5–3 µm vs. 4.5–5.5 µm for CaCO3) exhibited 3.5-fold greater stability, attributed to enhanced inter-capsule interactions via electrostatic and hydrophobic forces. Confocal microscopy confirmed the structural integrity of colloidosomes, featuring a liquid kerosene core encapsulated within a PMC shell. Temporal stability studies indicated structural degradation within 30 min, though 5% of colloidosomes retained integrity post-water evaporation. PMC-based colloidosomes exhibit significant application potential due to their integration of colloidosome functionality with PMC-derived structural features—semi-permeability, tunable shell thickness/composition, and stimuli-responsive behavior—enabling their adaptability to diverse technological and biomedical contexts. This innovation holds promise for applications in drug delivery, agrochemicals, and environmental technologies, where controlled release and stability are critical. The findings highlight the role of core material selection and solvent engineering in optimizing colloidosome performance, paving the way for advanced encapsulation systems.