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For the application of carbon nanotubes (CNTs), there are many practical problems to be solved. Large scale as-produced CNT especially single-walled CNTs (SWCNTs) inevitably contain impurities that produced in their growth process (Huo, et al. 2008) As-produced SWCNTs normally are of different chirality (Kataura, et al. 1999) Untreated CNTs are of high surface area and align into big bundles for their strong Van Der Waals attraction. The high aspect ratio and strong attraction between CNTs further leads to the physically entanglement of CNT ropes. The strong aggregation of CNTs gives rise to a highly complex network makes their uniformly dispersion into other substances hard to be achieved (Mitchell, et al. 2002). Engineering CNTs thus need variety of technologies to achieve CNT purification, separation, dispersion, stabilization, alignment, functionalization and organization (Baughman, et al. 2002). Many physical and chemical approaches have been developed to achieve these goals since the discovery of CNTs (Tasis, et al. 2006). On the route to the engineering of CNTs, biopolymer covalently and noncovalently functionalization of CNTs has been found to be promising way in highly effective realization these technologies. Initial great progress on dispersion of CNTs (Barisci, et al. 2004), CNT liquid crystal phase formation (Badaire, et al. 2005) and selective chiral SWCNTs enrichment (Zheng, et al. 2003) assisted by biopolymer DNA reveal that biopolymers are promising agents for high quality CNT materials preparation, which has soon attracted wide attentions on biopolymers assisted CNT engineering. Now widely obtainable, large scale production and low price agent polysaccharides have been found to be easier and commercially acceptable for achieving such goals. High concentration CNTs single dispersion and stabilization could be simply achieved by varieties of polysaccharides such as chitosan (Zhang, et al. 2007), gellan gum (Panhuis, et al. 2007), hydraulic acid (Moulton,et al. 2007) and etc. Physical purification of CNTs by chitosan funcitonalization has been approved to be easy processing and effective (Yang, et al. 2006). Aligning CNTs through liquid crystal phase of CNTs dispersed by polysaccharides has also been developed. The stable dispersed CNTs by biopolymers were further introduced into biomedical applications such as tissue engineering and drug delivery system, which broaden the application range of CNTs. For the bioactivity of biopolymers, their composites with CNTs provide excellent sensing performance. The biomimetic actuation based on CNT/biopolymer devices have also initially been shown to be of large and fast actuation displacement under low voltage electrical stimulation. |
