To accurately transport pharmaceutical agents to their specific target organs or cell types, you need a good carrier: nanoscopic capsules with surface elements that can "recognize" the target in question could do the trick.
To date, all methods for the production of such tiny capsules require preorganized structures or "molds" to shape hollow spheres and most methods require a lengthy, tedious synthetic or purification procedure. Korean researchers led by Kimoon Kim have now developed a very simple novel approach for the direct production of polymeric nanocapsules. As described in the journal Angewandte Chemie, this method is generally applicable to any monomers as long as they have a flat core and multiple polymerizable groups at the periphery. Additionally, if building block are chosen that are able to bind specific (bio)molecules very tightly, the surface of the capsule can be easily decorated with species that are recognized by cells, showing the transporter the way to reach its goal, such as a tumor cell.
To demonstrate the power of their new concept, Kim and his team chose rigid, disk-shaped monomers equipped with a ring of special molecular "hooks" that can be activated by UV light. When a solution containing these disks is irradiated, the hooks grab on to each other, linking the disks into little, two-dimensional "patches" that in turn hook on to other patches. Once they reach a certain size, the patches bend around and close off to form hollow spheres, which can then be filled with guest molecules. The size of the spheres is very uniform and depends largely on the solvent in which the linking reaction takes place. The researchers used this method to produce capsules with diameters ranging from 50 to 600 nm.