Department of Chemistry, National Chung-Hsing University, Taichung 402, Taiwan.
Anal Chim Acta. 2011 Dec 5;708(1-2):89-96. doi: 10.1016/j.aca.2011.10.013. Epub 2011 Oct 14.
Highly sensitive SERS substrates based on deposition of silver nanoparticles on commercially available filter paper were prepared in this work, and used to overcome problems found in analyses of aqueous samples. To prepare silver nanoparticle- (AgNP) doped filter substrates, a silver mirror reaction was used. The procedures for substrate preparation were systematically optimized. Pretreatment of filter paper, reaction time, temperature, and concentration of reagents for silver mirror reactions were studied. The morphologies of the resulting substrates were characterized by field-emission scanning electron microscopy (FE-SEM) and correlated with the SERS signals by probing with p-nitrothiophenol (pNTP). Filter papers with different pretreatments were found to have different sizes and distributions of AgNPs. The best performance was found when filter paper was pre-treated with ammonia solution before growth of AgNPs. Based on the SEM images, the resulting AgNPs had roughly spherical shape with a high degree of uniformity. The silver-coated filter paper substrates provide much higher SERS signals compared to glass substrates and the reproducibility was improved significantly. Based on statistical analyses, the relative standard deviations for substrate-to-substrate and spot-to-spot were both were less than 8% and the enhancement factors for the substrates were, in general, higher than 107. The SERS substrates were used to selectively detect tyrosine in aqueous solution. Results indicate that filter-based SERS substrates are highly suited to detection of tyrosine. Compared to glass-based SERS substrates, 50 times more SERS signal was observed in detection of tyrosine. The linear range can be up to 100 μM with a detection limit of 625 nM (SN(-1)=3).
本工作制备了基于商业滤纸沉积银纳米粒子的高灵敏度 SERS 基底，用于克服分析水溶液样品时遇到的问题。为了制备银纳米粒子掺杂的滤纸片基底，采用银镜反应。系统地优化了基底制备的过程。研究了滤纸预处理、反应时间、温度和银镜反应试剂浓度等因素对基底制备的影响。用场发射扫描电子显微镜（FE-SEM）对所得基底的形貌进行了表征，并通过探测对硝基硫酚（pNTP）与 SERS 信号进行了关联。结果表明，不同预处理的滤纸具有不同尺寸和分布的 AgNPs。当在生长 AgNPs 之前用氨溶液预处理滤纸时，得到的性能最佳。基于 SEM 图像，所得的 AgNPs 具有大致球形的形状，且具有很高的均匀性。与玻璃基底相比，镀银滤纸基底提供了更高的 SERS 信号，且重现性得到了显著提高。基于统计分析，基底之间和点之间的相对标准偏差均小于 8%，且基底的增强因子通常高于 107。该 SERS 基底用于选择性地检测水溶液中的酪氨酸。结果表明，基于滤纸的 SERS 基底非常适合检测酪氨酸。与玻璃基 SERS 基底相比，检测酪氨酸时观察到的 SERS 信号增强了 50 倍。线性范围可达 100 μM，检测限为 625 nM（SN(-1)=3）。
