Polymeric capsules have been widely used in the cosmetic, food, textile, adhesive and agricultural fields as a reservoir of functional agents in making self-healing materials.However, the development of novel capsules that can easily be produced and that have special properties is still desired.

Recently, new progress was made in this area by the research group of Material Surface and Interface Behavior of the State Key Laboratory of Solid Lubrication of the Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences. In their work (Chem. Commun., 2009, 6789–6791), Polydopamine (Pdop) nano/microcapsules are readily produced through the oxidative polymerization of dopamine and the spontaneous deposition of Pdop on the template surface, followed by the removal of the template.

The preparation method is easy and the surface chemistry property of the template is independent. Most importantly, they exhibit outstanding unidirectional permeability to Rh6G: they can uptake Rh6G with different rate but cannot release Rh6G in an aqueous buffer solution. In contrast, in ethanol, the trend is reversed: they cannot uptake but rapidly release Rh6G.. The dopamine unit is very observable in vivo, making Pdop a candidate for potential biomedical applications. Polydopamine capsules can serve as a versatile platform for secondary surface mediated reactions, thus showing potential in the application of regulating the loading and release behavior of Pdop capsules for different encapsulation materials.

This work was supported by the ‘‘Hundred Talents Program’’ of CAS and the key project of NSFC (50835009, 50621702).

Paper abstract: http://www.rsc.org/publishing/journals/CC/article.asp?doi=b910679k

The suggested structure of polydopamine and unidirectional
permeability behavior of polydopamine capsules.
(Picture provided by State Kay Laboratory of Solid Lubrciation)