Xue Yuxiang, Ma Xinyao, Feng Xue, Roberts Sam, Zhu Guangyu, Huang Yi, Fan Xianfeng, Fan Jun, Chen Xianfeng
School of Engineering, Institute for Bioengineering, University of Edinburgh, The King's Buildings, EH9 3JL Edinburgh, U.K.
Department of Materials Science and Engineering, City University of Hong Kong, 83 Tat Chee Ave, 00000 Kowloon Tong, Hong Kong, SAR, P. R. China.
ACS Appl Nano Mater. 2023 Jun 27;6(13):11572-11580. doi: 10.1021/acsanm.3c01593. eCollection 2023 Jul 14.
Gold nanostructures have attracted broad attention. Among various nanostructures, gold nanobipyramids have shown great potential in sensing, biomedicine, environmental protection, chemical catalysis, and optics due to their unique physical and optical properties and ease of chemical functionalization. Compared with other plasmonic nanostructures, gold nanobipyramids possess narrow optical resonances, stronger plasmonic local field enhancement, and size- and shape-dependent surface plasmon resonance. However, the synthesis and purification of homogeneous gold nanobipyramids are very challenging. The gold nanobipyramids synthesized via the commonly used seed-mediated growth method have low yields and are often coproduced with spherical nanoparticles. In this study, we reported a temperature-derived purification method for the isolation of gold bipyramids. In the presence of salt, by altering the temperature of the solution, large gold bipyramids can be separated from small spherical nanoparticles. As a result, a yield of as high as 97% gold nanobipyramids can be achieved through a single round of purification, and correspondingly, the ratio between the longitudinal surface plasmon resonance (LSPR) and transverse SPR intensity significantly increases to as high as 6.7. The purified gold nanobipyramids can be used as a colorimetric probe in the detection of tannic acid with a detection limit of 0.86 μM and a linear detection range from 1.25 to 37.5 μM.
金纳米结构已引起广泛关注。在各种纳米结构中，金纳米双锥由于其独特的物理和光学性质以及易于进行化学功能化，在传感、生物医学、环境保护、化学催化和光学等领域展现出巨大潜力。与其他等离子体纳米结构相比，金纳米双锥具有窄光学共振、更强的等离子体局部场增强以及尺寸和形状依赖的表面等离子体共振。然而，均匀金纳米双锥的合成和纯化极具挑战性。通过常用的种子介导生长法合成的金纳米双锥产率低，且常与球形纳米颗粒共同产生。在本研究中，我们报道了一种用于分离金双锥的温度衍生纯化方法。在盐存在的情况下，通过改变溶液温度，大的金双锥可以从小的球形纳米颗粒中分离出来。结果，通过一轮纯化可实现高达97%的金纳米双锥产率，相应地，纵向表面等离子体共振（LSPR）与横向SPR强度之比显著增加至高达6.7。纯化后的金纳米双锥可作为比色探针用于检测单宁酸，检测限为0.86 μM，线性检测范围为1.25至37.5 μM。
