Herein, a novel method has been developed for in situ synthesis and embedding of silver nanoclusters (AgNCs) into polyvinyl alcohol and borax hydrogel (PBH) without adding any reducing agent. A three-dimensional network of polyvinyl alcohol and borax is formed, and at the same time the silver ions penetrate into the hydrogel, reduced to silver and trapped into the hydrogel bed. The characteristics of this hydrogel nanocomposite were investigated by energy dispersive X-ray spectroscopy and transmission electron microscopy (TEM). It was also observed that the fluorescence intensity of embedded AgNCs into polyvinyl alcohol and borax hydrogel (AgNCs-PBH) was enhanced and quenched in the presence of Fe (III) and thiosulfate, respectively. Therefore a novel dual on-off fluorescence sensor was developed based on polyvinyl alcohol-borax hydrogel for the first time. After preparing this new probe, the effect of Fe (III) and thiosulfate was investigated. The size- depending of label free AgNCs was found to be responsible for the enhancing and quenching of the fluorescence as well as obvious color changing. Under the approved condition, the linear ranges were validated over the concentration of 0.14–27.0 µmol L⁻¹ and 0.1–1.0 µmol L⁻¹ for Fe (III) and thiosulfate, respectively. The limit of detection based on three times the standard deviation of the blank was 0.045 and 0.060 µmol L⁻¹ for Fe (III) and thiosulfate, respectively. The relative standard deviation for intra-day and inter-day determinations of both Fe (III) and thiosulfate were in the range of 3.23–5.17% (n = 10). This sensing probe was used for Fe (III) detection in some food samples and thiosulfate in water samples with acceptable results and good recoveries.

本文中，已经开发了一种新颖的方法，用于在不添加任何还原剂的情况下原位合成并将银纳米团簇（AgNC）嵌入聚乙烯醇和硼砂水凝胶（PBH）中。形成了聚乙烯醇和硼砂的三维网络，同时银离子渗透到水凝胶中，还原为银并被捕获到水凝胶床中。通过能量色散X射线光谱和透射电子显微镜（TEM）研究了该水凝胶纳米复合材料的特性。还观察到，分别在Fe（III）和硫代硫酸盐的存在下，嵌入AgNCs进入聚乙烯醇和硼砂水凝胶（AgNCs-PBH）的荧光强度得到增强和猝灭。因此，首次开发了基于聚乙烯醇-硼砂水凝胶的新型双开关荧光传感器。在准备好这种新探针后，研究了铁（III）和硫代硫酸盐的作用。发现大小依赖于无标记的AgNC负责荧光的增强和猝灭以及明显的颜色变化。在批准的条件下，线性范围在0.14–27.0 µmol L的浓度范围内得到验证Fe（III）和硫代硫酸盐分别为^-1和0.1–1.0 µmol L ^-1。基于三倍空白标准偏差的检出限分别为Fe（III）和硫代硫酸盐为0.045和0.060 µmol L ^-1。Fe（III）和硫代硫酸盐的日内和日间测定的相对标准偏差在3.23–5.17％的范围内（n = 10）。该传感探头用于某些食品样品中的Fe（III）检测和水样品中的硫代硫酸盐检测，结果令人满意，回收率也很高。