Colorimetric detection by etching based on metal nanoparticles is one of the most commonly portable detection methods, but there are problems such as poor particle controllability and irregular etching. In this paper, a novel Ag lateral coated Au nanobipyramids nanostructure (Au@Ag LCNBPs) for multi-colorimetric detection of Fe is prepared through the mediation of dimethyl sulfoxide (DMSO). When DMSO is used to cover the surface of Au nanobipyramids (Au NBPs), it greatly affects the way Ag coated Au NBPs. When the volume ratio of DMSO is 25%, Ag is no longer deposited at the tip, but gradually deposited on the side of the Au NBPs to form the Au@Ag LCNBPs. The long axis cross-section of the Au@Ag LCNBPs takes the shape of a hexagon. As the Ag content increases, the width of the Ag layer gradually increases, the cross-section gradually converts to a positive hexagonal shape, and the aspect ratio of the whole structure decreases, leading to the blueshift of the longitudinal LSPR peak. This mode of deposition is different from the longitudinal deposition reported in the previous literature. A multi-colorimetric detection method for Fe using the etching of the Ag layer by Au@Ag LCNBPs has been developed. This method exhibits a good exponential correlation in the concentration range of 1–210 μM with the detection limit of 200 nM. With the increase of Fe, the colloid color shows the change of yellow, orange, red, purple, blue, green and colorless. The etching process can be completed in about 30 s. This nanostructure achieves two etching modes of the Ag layer by Fe, uniform etching and concave etching. Moreover, it demonstrates that the enormous potential of Au@Ag LCNBPs in colorimetric etching detection.

中文翻译：

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DMSO 介导的银侧面涂覆金纳米双锥体：具有均匀蚀刻的 Fe3+ 超快比色检测平台

基于金属纳米颗粒的蚀刻比色检测是最常用的便携式检测方法之一，但存在颗粒可控性差、蚀刻不规则等问题。本文通过二甲基亚砜（DMSO）的介导制备了一种新型的银侧面涂覆的金纳米双锥纳米结构（Au@Ag LCNBPs），用于多比色检测铁。当DMSO用于覆盖Au纳米双锥体(Au NBPs)的表面时，它极大地影响了Ag包覆Au NBPs的方式。当DMSO的体积比为25%时，Ag不再沉积在尖端，而是逐渐沉积在Au NBP的侧面，形成Au@Ag LCNBP。 Au@Ag LCNBP 的长轴横截面呈六边形。随着Ag含量的增加，Ag层的宽度逐渐增大，截面逐渐转变为正六边形，整个结构的纵横比减小，导致纵向局域表面等离子体共振峰蓝移。这种沉积方式与以往文献报道的纵向沉积不同。开发了一种利用 Au@Ag LCNBP 蚀刻 Ag 层的多比色检测方法。该方法在 1–210 μM 的浓度范围内表现出良好的指数相关性，检测限为 200 nM。随着Fe的增加，胶体颜色呈现黄色、橙色、红色、紫色、蓝色、绿色和无色的变化。蚀刻过程可在约30s内完成。该纳米结构实现了Fe对Ag层的刻蚀两种模式：均匀刻蚀和凹面刻蚀。此外，它证明了 Au@Ag LCNBP 在比色蚀刻检测中的巨大潜力。