Qianqian Ma, and Xinju Yang Effects of carbon nanotubes on the aggregation of Aβ proteins studied by atomic force microscopy Qianqian Ma, and Xinju Yang Department of Physics, State Key Laboratory of Surface Physics, Fudan University, Shanghai 200433, P. R. China 1. Introduction The aggregation of amyloid beta protein (Aβ) is taken as the main possible cause of the Alzheimer‘s disease (AD). How to inhibit the aggregation of Aβ peptide has been an intensive subject. Here the aggregations of Aβ 1-40, Aβ 16-22, and Aβ25-35 proteins are investigated by atomic force microscopy(AFM) with and without carbon nanotubes (CNTs). It is found that CNTs can inhibit the formation of Aβ 16-22 fibers, and adsorb the oligomers of Aβ 1-40 on CNTs’ surface, which make protein to form short-fibers. But the effect of CNTs on aggregation of Aβ 25-35 is not observed. 2. The effects of carbon nanotubes on the aggregation of Aβ16-22 E D’ E’ C’ A’ B’ A D C B 3. The effects of carbon nanotubes on the aggregation of Aβ 25-35 as prepared 3 days 8 days 14 days Time Aβ 16-22 Aβ 16-22+CNTs   (nm) 15 A A’ D C B B’ C’ D’ Sample Aβ 25-35 as prepared   (nm) 10 Aβ 25-35+CNTs 3 hours 500nm Sample The effect of CNTs on aggregation of Aβ 25-35 is not observed. 6 hours 4. The effects of carbon nanotubes on the aggregation of Aβ 1-40 as prepared 3 days 7 days 14 days Time A B C D 9 hours Aβ 1-40   (nm) 10 A’ B’ C’ D’ 7 days Aβ 1-40+CNTs 1μm 500nm Time Sample CNTs inhibit the formation of Aβ16-22 fibers significantly. CNTs make Aβ 1-40 protein to form short-fibers (taken as protofibrils) Reference [1]. Yon JM. Protein folding: a perspective for biology, medicine and biotechnology. Braz J Med Biol Res 2001;34(4):419–35. [2] Harris PJF. Carbon nanotubes and related structures. New York: Cambridge University Press; 1999 [3] Ghule, A.V., et al., Carbon nanotubes prevent 2,2,2 trifluoroethanol induced aggregation of protein. CARBON, 2007. 45(7): p. 1586-1589. 5. Conclusion The effect of CNTs on the aggregation of Aβ 16-22 is to inhibit the formation of fibers. CNTs make Aβ 1-40 protein form short-fibers(taken as protofibrils), inhibition the formation of fibers. The effect of CNTs on inhibition to the aggregation of Aβ 25-35 is not observed.