科研之友
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摘要
Gold nanostructures have attracted broad attention. Amongvariousnanostructures, gold nanobipyramids have shown great potential insensing, biomedicine, environmental protection, chemical catalysis,and optics due to their unique physical and optical properties andease of chemical functionalization. Compared with other plasmonicnanostructures, gold nanobipyramids possess narrow optical resonances,stronger plasmonic local field enhancement, and size- and shape-dependentsurface plasmon resonance. However, the synthesis and purificationof homogeneous gold nanobipyramids are very challenging. The goldnanobipyramids synthesized via the commonly used seed-mediated growthmethod have low yields and are often coproduced with spherical nanoparticles.In this study, we reported a temperature-derived purification methodfor the isolation of gold bipyramids. In the presence of salt, byaltering the temperature of the solution, large gold bipyramids canbe separated from small spherical nanoparticles. As a result, a yieldof as high as 97% gold nanobipyramids can be achieved through a singleround of purification, and correspondingly, the ratio between thelongitudinal surface plasmon resonance (LSPR) and transverse SPR intensitysignificantly increases to as high as 6.7. The purified gold nanobipyramidscan be used as a colorimetric probe in the detection of tannic acidwith a detection limit of 0.86 & mu;M and a linear detection rangefrom 1.25 to 37.5 & mu;M.
