New materials for electrochemical sensing VI: Carbon nanotubes

Carbon nanotubes (CNTs) combine in a unique way high electrical conductivity, high chemical stability and extremely high mechanical strength. These special properties of both single-wall (SW) and multi-wall (MW) CNTs have attracted the interest of many researchers in the field of electrochemical sensors. This article demonstrates the latest advances and future trends in producing, modifying, characterizing and integrating CNTs into electrochemical sensing systems. CNTs can be either used as single probes after formation in situ or even individually attached onto a proper transducing surface after synthesis. Both SWCNTs and MWCNTs can be used to modify several electrode surfaces in either vertically oriented "nanotube forests" or even a non-oriented way. They can be also used in sensors after mixing them with a polymer matrix to form CNT composites. We discuss novel applications of CNTs in electrochemical sensors, including enzyme-based biosensors, DNA sensors and immunosensors, and propose future challenges and applications.