School of Chemistry, Sun Yat-sen University, Guangzhou 510006, China.
Anal Chem. 2023 Apr 18;95(15):6399-6409. doi: 10.1021/acs.analchem.3c00209. Epub 2023 Apr 5.
In this work, Ag nanoparticles (AgNPs) were embedded into a poly(-isopropylacrylamide)-laponite (Ag/PNIP-LAP) hydrogel membrane for highly sensitive surface-enhancement Raman scattering (SERS) detection. In situ polymerization was initiated by UV light to encapsulate AgNPs in a PNIP-LAP hydrogel to prepare a highly active SERS membrane with a three-dimensional structure. Due to the surface plasmon resonance and high swelling/shrinkage ratio of the Ag/PNIP-LAP hydrogel SERS membrane, its network structure has a "sieving" effect, which makes it easier for hydrophilic small-molecule targets to enter the sterically confined hydrogel, and the AgNPs are close to each other to form a Raman "hot spot" through the shrinkage of the hydrogel, at the same time, the analyte is enriched in the confined space and close to the AgNPs to form a stronger SERS signal. The characterization of the SERS activity of the Ag/PNIP-LAP hydrogel showed that the prepared three-dimensional membrane had high detection sensitivity for urotropine, 2,5-dimethylpyrazine, pyrazinamide, and pyrazine; the detection limits (/ = 3) were 17.4, 31.0, 53.1, and 1.11 μg/L, and the analytical time was 35 min. Due to the hydrophilicity of the Ag/PNIP-LAP hydrogel membrane, the small molecules can easily enter the SERS membrane, and the hydrophobic macromolecules are blocked outside the SERS membrane. The SERS method has good selectivity, stability, and reproducibility. The SERS method was applied to the detection of urotropine in dried bean curd sticks, 2,5-dimethylpyrazine in nuts and potato chips, and pyrazinamide in human plasma with recoveries of 81.8-116.8% and the relative standard deviation within 4.9-9.9%. The results matched well with that found by the corresponding chromatographic methods. The proposed method has the advantages of simple sample pretreatment, speediness, high sensitivity, and good selectivity to hydrophilic compounds and has potential application in the rapid on-site detection.
在这项工作中，将银纳米粒子 (AgNPs) 嵌入聚（异丙基丙烯酰胺）-皂土 (Ag/PNIP-LAP) 水凝胶膜中，用于高灵敏度的表面增强拉曼散射 (SERS) 检测。通过紫外光引发原位聚合，将 AgNPs 封装在 PNIP-LAP 水凝胶中，制备具有三维结构的高活性 SERS 膜。由于 Ag/PNIP-LAP 水凝胶 SERS 膜的表面等离子体共振和高溶胀/收缩比，其网络结构具有“筛分”效应，使亲水性小分子目标物更容易进入空间受限的水凝胶，AgNPs 通过水凝胶的收缩彼此靠近，形成拉曼“热点”，同时，分析物在受限空间中被富集并靠近 AgNPs 以形成更强的 SERS 信号。Ag/PNIP-LAP 水凝胶的 SERS 活性表征表明，所制备的三维膜对六亚甲基四胺、2,5-二甲基吡嗪、吡嗪酰胺和吡嗪具有高检测灵敏度；检测限 (/ = 3) 分别为 17.4、31.0、53.1 和 1.11 μg/L，分析时间为 35 分钟。由于 Ag/PNIP-LAP 水凝胶膜的亲水性，小分子可以很容易地进入 SERS 膜，而疏水性大分子则被阻挡在 SERS 膜之外。SERS 方法具有良好的选择性、稳定性和重现性。SERS 方法应用于干豆腐棒中六亚甲基四胺、坚果和薯片 2,5-二甲基吡嗪以及人血浆中吡嗪酰胺的检测，回收率为 81.8-116.8%，相对标准偏差在 4.9-9.9% 以内。结果与相应的色谱方法吻合良好。该方法具有样品预处理简单、快速、灵敏度高、对亲水性化合物选择性好的优点，在快速现场检测中具有潜在的应用前景。
