Credit: © 2009 Wiley

Biomaterials used in medical devices that come in contact with blood must prevent the adhesion of platelets because these cells, which are responsible for blood coagulation, can create dangerous blood clots and cause the device to fail. Material surfaces can be treated chemically or biologically, or made to have submicrometre architectures to suppress platelet adhesion. Researchers at the National Center for Nanoscience and Technology of China, the Institute of Chemistry, the Chinese Academy of Sciences in Beijing and elsewhere in China now show that multiscale architectures can make materials more compatible with blood under flow conditions than single-scale structures1.

Using conventional methods, Dong Han, Lei Jiang and colleagues created four types of surfaces: a smooth one, one with nanosize protrusions, one with submicrometre ridges and another with multiscale structures made of the same ridges but with nanosize protrusions on them. When platelets were allowed to flow over the substrates in a flow chamber, the multiscale substrate showed the lowest number of platelet clots. Furthermore, atomic force microscopy studies found that the interaction force of a particle with the surface was lowest for the multiscale architecture.

Although the mechanisms remain unresolved, it is believed that the multiscale design can remodel the boundary conditions of liquids and thus lower the collision frequency of platelets with the surface.