Multilayer microcapsules with tailored structures for bio-related applications

The technique for fabrication of hollow multilayer microcapsules is initially established by layer-by-layer (LbL) assembly of oppositely charged polyelectrolytes onto sacrificial colloidal particles followed by core removal. It has the advantages of precise control over the size, shape, composition, wall thickness and functions of the obtained hollow microcapsules. More recently, the technique has been developed fast from the fabrication and basic property investigation to functionalization and applications, in particular in bio-related fields such as controlled drug delivery, biosensors and bioreactors. In this article, we shall review recent advances in property manipulation of electrostatic and hydrogen bonded microcapsules by chemical crosslinking, and microcapsules assembled by other driving forces such as covalent interaction, base pair interaction, host-guest interaction and van der Waals interaction. Then the possible applications of LbL microcapsules in bio-related fields are summarized with particular emphasis on very recent achievements in terms of loading and release, surface modification for stealth function or targeting and use as biosensors and bioreactors.