Biological reactions are generally catalysed by enzymes. Often, in various attempts to protect and stabilise them, they are immobilised by methods like entrapment, cross-linking, covalent binding, or others. Despite the efforts, these methods often lead to denaturing during use. Encapsulation, therefore, allows protection of the enzyme as well as the chance to integrate a chemical co-catalyst.

Colloidosomes, of 10-20 µm in size, encapsulate the enzyme (biocatalyst) in an aqueous core. Around this aqueous droplet, titania particles (chemical co-catalyst) is added. The entire assembly is then encased in a net-like polymeric shell for rigidity and protection. The shell is also made responsive to enable mass transfer control.

To synthesise this, a self-assembly method is employed. This utilises the migration of colloid particles to a water-oil interface. Within this droplet, the enzyme, titania and colloid particles are initially dispersed. The droplet is then further stabilised by locking the colloid particles via sintering. The advantages of this fabrication include simple synthesis procedures and no contact of the enzyme with denaturing solvents. Incorporation of titania and responsive polymers in the shell has been achieved and the rate of release of a dye from the core will be discussed.