Abstract The present study elucidates the preparation of colorimetric Au@Ag core-shell nanoparticles (Au@Ag core-shell NPs) probe for sensitive, label-free and rapid sensing of trace levels of cysteamine (CSH). The Au@Ag core-shell NPs were prepared by a simple chemical reduction method. The physico-chemical properties of the Au@Ag core-shell NPs were extensively characterized by various spectroscopic and microscopic techniques. Upon the successive addition of increasing concentrations of CSH to Au@Ag core-shell NPs, the absorption intensity showed a decrease with the formation of a new peak at 652 nm. In the presence of CSH, the negatively charged citrate ions that are adsorbed on the surface of Au@Ag core-shell NPs readily get replaced by the CSH and result in the aggregation of NPs. The observed absorption spectral evolution is proportional with the addition of increasing concentrations of CSH. The Au@Ag core-shell NPs showed high selectivity towards the selectivedetermination of CSH even in the presence of other interfering biomolecules. The proposed sensing strategy can selectively detect CSH in the concentrations range of 1.00 × 10−7 mol dm−3 to 8.00 × 10−7 mol dm−3 with a limit of detection as low as 0.33 nM. The practical applicability of the sensing probe is further demonstrated by performing the detection of CSH in serum and urine samples with high accuracy.

中文翻译：

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使用 Au@Ag 核-壳纳米粒子对半胱胺进行直接视觉和比色传感应用的简单测定

摘要 本研究阐明了用于灵敏、无标记和快速检测痕量半胱胺 (CSH) 的比色 Au@Ag 核壳纳米粒子 (Au@Ag 核壳 NPs) 探针的制备。Au@Ag 核壳纳米粒子是通过简单的化学还原方法制备的。Au@Ag核壳纳米粒子的理化性质通过各种光谱和显微技术得到广泛表征。在向 Au@Ag 核壳 NPs 中连续添加增加浓度的 CSH 后，吸收强度显示出降低，并在 652 nm 处形成新峰。在 CSH 存在下，吸附在 Au@Ag 核壳 NPs 表面的带负电荷的柠檬酸根离子很容易被 CSH 取代并导致 NPs 聚集。观察到的吸收光谱演变与 CSH 浓度的增加成正比。即使在存在其他干扰生物分子的情况下，Au@Ag 核壳 NPs 也对 CSH 的选择性测定显示出高选择性。所提出的传感策略可以选择性地检测 1.00 × 10-7 mol dm-3 至 8.00 × 10-7 mol dm-3 浓度范围内的 CSH，检测限低至 0.33 nM。通过高精度检测血清和尿液样本中的 CSH，进一步证明了传感探针的实际适用性。所提出的传感策略可以选择性地检测 1.00 × 10-7 mol dm-3 至 8.00 × 10-7 mol dm-3 浓度范围内的 CSH，检测限低至 0.33 nM。通过高精度检测血清和尿液样本中的 CSH，进一步证明了传感探针的实际适用性。所提出的传感策略可以选择性地检测 1.00 × 10-7 mol dm-3 至 8.00 × 10-7 mol dm-3 浓度范围内的 CSH，检测限低至 0.33 nM。通过高精度检测血清和尿液样本中的 CSH，进一步证明了传感探针的实际适用性。