# Eco-Friendly Fungal Chitosan-Silica Dual-Shell Microcapsules with Tailored Mechanical and Barrier Properties for Potential Consumer Product Applications

## TL;DR

Researchers created eco-friendly microcapsules using fungal chitosan and silica to improve durability and reduce plastic pollution for use in consumer products.

## Contribution

A new method to fabricate dual-shell microcapsules using fungal chitosan and silica for enhanced mechanical and barrier properties.

## Key findings

- Dual-shell microcapsules showed a rupture stress of 3.0 ± 0.2 MPa, significantly higher than single-shell microcapsules.
- Dual-shell microcapsules released only ∼2.5% of fragrance oil after 20 days in water, compared to over 10% for single-shell ones.

## Abstract

Commercial perfume
microcapsules are becoming popular across the
globe to fulfill consumers’ demands. However, most of microcapsules
rely on synthetic polymers and/or animal-sourced ingredients to form
the shells. Therefore, replacement of the shell materials is imperative
to minimize environmental microplastic pollution, as well as to meeting
peoples’ needs, religious beliefs, and lifestyles. Herein,
we report a methodology to fabricate environmentally benign dual-shell
(fungal chitosan-SiO2) microcapsules laden with fragrance
oil (hexyl salicylate). Anionically stabilized oil droplets were coated
with fungal chitosan via interfacial electrostatic interactions at
pH 2, which were then covered by an inorganic coating of SiO2 produced via external alkaline mineralization of sodium silicate.
Core–shell microcapsules with a spherical morphology were achieved.
Under compression, dual-shell chitosan-SiO2 microcapsules
yielded a mean nominal rupture stress of 3.0 ± 0.2 MPa, which
was significantly higher than that of single-shell microcapsules (1.7
± 0.2 MPa). After 20 days in neutral pH water, only ∼2.5%
of the oil was released from dual-shell microcapsules, while single-shell
microcapsules cumulatively released more than 10%. These findings
showed that the additional SiO2 coating significantly enhanced
both mechanical and barrier properties of microcapsules, which may
be appealing for multiple commercial applications, including cosmetics
and detergents.