Light-triggered drug release and delivery

A team of researchers has developed a novel method to encapsulate large cargo in a coat made up of a mosaic of oppositely charged nanoparticles, which can disintegrate upon light exposure to allow their delivery on demand. 

Colloidosomes are tiny capsules that are assembled when colloidal particles arrange at the interface between the oily and aqueous phases of droplets in an emulsion, forming hollow structures that can be loaded with small molecules such as drugs, or large molecules such as proteins or nucleic acids. 

A team led by Niveen M. Khashab at KAUST in Saudi Arabia synthesized these colloidosomes using two different functionalizations of organosilica nanopaticles, with negative and positive surface charges.

Their assembly in this manner allows their size and porosity to be finely controlled. 

However, to be useful as delivery vehicles, a delicate balance has to be maintained between stability and leak-proofing of the coat, and its ability to break open to release its cargo. 

The mosaic of opposing charges, which the coat is made of, allow the colloidosomes to assemble by electrostatic interaction, removing — for the first time — the need to further stabilize the capsules using covalent crosslinking or polymerization, which can compromise their release property. 

Exposure to light creates a photochemical reaction that reverses the charge on the positively charged nanoparticles, demolishing the stabilizing attractive force and introducing a repulsion instead. 

This repulsion causes the colloidosomes to rapidly dissociate and release their contents. 

The team presented their results in Angewandte Chemie^1. 

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