[1] [1] Fleischmann M, Hendra P J, McQuillan A J. Chem. Phys. Lett., 1974, 26: 163.

[2] [2] Jeanmaire D L, Van Duyne R P. J. Electroanal. Chem., 1977, 84: 1.

[3] [3] Albrecht M G, Creighton J A. J. Am. Chem. Soc., 1977, 99: 5215.

[4] [4] Kneipp K, Wang Y, Kneipp H, et al. Phys. Rev. Lett., 1997, 78: 1667.

[5] [5] Nie S M, Emery S R. Science, 1997, 275: 1102.

[6] [6] Moskovits M. Rev. Mod. Phys., 1985, 57: 783.

[7] [7] Anker J N, Hall W P, Lyandres O, et al. Nat. Mater., 2008, 7: 442.

[8] [8] Tian Z Q, Ren B, Li J F, et al. Chem. Commun., 2007. 3514.

[9] [9] Wu D Y, Li J F, Ren B, et al. Chem. Soc. Rev., 2008, 37: 1025.

[10] [10] Lu L H, Wang H, Zhou Y, et al. Chem. Commun., 2002. 144.

[11] [11] Santra S, Zhang P, Wang K, et al. Anal. Chem., 2001, 73: 4988.

[12] [12] Brown K R, Lyon A, Fox A P, et al. Chem. Mater., 2000, 12: 314.

[13] [13] Jana N R, Gearheart L, Murphy C J. J. Phys. Chem. B, 2001, 105: 4065.

[14] [14] Rodriguez-Fernandez J, Perez-Juste J, Abajo F J, et al. Langmuir, 2006, 22: 7007.

[15] [15] Fang P P, Li J F, Yang Z L, et al. J. Raman Spectrosc., 2008, 39: 1679.

[16] [16] Link S, El-Sayed M A. J. Phys. Chem. B, 1999, 103: 4212.

[17] [17] Tiwari V S, Oleg T, Darbha G K, et al. Chem. Phys. Lett., 2007, 446: 77.

[18] [18] Yang K H, Liu Y C, Yu C C. J. Mater. Chem., 2008, 18: 4849.

[19] [19] Lin X M, Cui Y, Xu Y H, et al. Anal. Bioanal. Chem., 2009, 394: 1729.