The use of synthetic materials across a range of scientific and engineering fields has supported a revolution in these areas. The challenge for healthcare is that many synthetic materials can be unstable and toxic. Researchers at the Laboratory of Pharmaceutical Physical Chemistry, Gifu Pharmaceutical University, under the direction of Associate Professor Dr Yasushi Sasai, are attempting to develop methods for effective functionalisation of solid materials for pharmaceutical and medical applications. It is their hope that they can improve the biocompatibility of synthetic materials. A polymer brush is a technique where polymers can be tethered to a surface of a substrate. This method allows synthetic materials to become biocompatible with specific biological environments, and hence be used as efficient and appropriate biomaterials. "It is imperative for synthetic materials produced or processed by humans to be highly stable, non-toxic and non-immunogenic," highlights Sasai. However, the majority of these materials are hydrophobic and with poor biocompatibility regarding their target biological environment. So, to use synthetic materials in biomedical research and applications, it is necessary to change the surface of these materials and to make sure they are as fully compatible with the targeted environment. He says that thanks to major advances in chemistry, it is now possible to design and synthesise a variety of polymers, meaning that properties and functions can be introduced to materials by using surface modification techniques. "Applications of polymer brushes have been rapidly growing as a result of the ability to synthesise well-defined polymer brushes consisting of a wide range of monomer from various type of substrates such as polymers, metals and other inorganic substrates by using surface-initiated polymerisation techniques," explains Sasai. The development of hydrophilic polymer brushes with anti-fouling properties and low friction surfaces has been of great interest for improving the biocompatibility of materials. "We have been developing original surfaces for fabricating biocompatible materials, biosensing platforms, and cell culture materials by using plasma techniques, surface-initiated polymerisation techniques, and other physical and chemical modifications," he comments. One of the key properties of polymer brushes is the high density of their grafted chains. "High density translates into a very limited space, and hence to a solid extension of the chains," points out Sasai. "Irradiation with plasma induces structure-dependent reaction and allows for the fabrication of polymer properties that cannot be achieved by simple polymer physical and chemical modification; and this is very useful when it comes to optimising the surface properties of polymer brushes.