Preparation of gold nanorods with different aspect ratio and the optical response to solution refractive index

Abstract

In this paper, we report that gold nanorods with different aspect ratios are controllably synthesised by a facile modified seed-mediated growth procedure. The growth rate of gold nanorods is lowered by adding H₂SO₄, and the yield of gold nanorods is improved. Increasing the concentration of AgNO₃ yields gold nanorods with different aspect ratios that differed from 1.83 to 5.04. To prevent aggregation of cetyltrimethylammonium bromide (CTAB)-capped gold nanorods and investigate the sensitivity to the solution refractive index, surface modification is carried out. After assembling poly (sodium-p-styrensulfonate) onto the surface of gold nanorods, the samples can disperse well in water and dimethyl sulfoxide. The localised surface plasmon resonance (LSPR) wavelength of the as-prepared gold nanorods redshifts with increasing the refractive index of the solvent and a good linear relationship between LSPR peaks and refractive index is achieved.

Keywords:

• gold nanorod
• surface plasmon resonance
• surface modification
• dielectric sensitivity

Acknowledgements

This work is supported by the National Key Basic Research Program973 Project (2010CB933901), Important National Science & Technology Specific Project (2009ZX10004-311), National Natural Scientific Fund (No. 20803040), Special project for nanotechnology from Shanghai (No. 1052nm04100), New Century Excellent Talent of Ministry of Education of China (NCET-08-0350), Shanghai Science and Technology Fund (10XD1406100), the youth fund research project of Yunnan University of Nationalities (2012QN01) and the general program of the application and basic research foundation of Yunnan province (2013FZ080).