Colaianni L, Kung S C, Taggart D K, Picca R A, Greaves J, Penner R M, Cioffi N
Dipartimento di Chimica, Università degli Studi di Bari "Aldo Moro", Via Orabona 4, 70126, Bari, Italy.
Anal Bioanal Chem. 2014 Jul;406(19):4571-83. doi: 10.1007/s00216-014-7876-7. Epub 2014 Jul 1.
The surface chemistry of gold nanowires (AuNWs) has been systematically assessed in terms of contamination and cleaning processes. The nanomaterial's surface quality was correlated to its performance in the matrix-free laser desorption ionization mass spectrometry (LDI-MS) analysis of low molecular weight analytes. Arrays of AuNWs were deposited on glass slides by means of the lithographically patterned nanowire electrodeposition technique. AuNWs were then characterized in terms of surface chemical composition and morphology using X-ray photoelectron spectroscopy, scanning electron microscopy and atomic force microscopy. AuNWs were subjected to a series of well-known cleaning procedures with the aim of producing the best performing surfaces for the LDI-MS detection of leucine enkephalin, chosen as a model analyte with a molar mass below 1,000 g/mol. Prolonged cyclic voltammetry in 2 M sulfuric acid and, most of all, oxygen plasma cleaning for 5 min provided the best results in terms of simpler (interference-free) and more intense mass spectrometry spectra of the reference compound. The analyte always ionized as the sodiated adduct, and leucine enkephalin limits of detection of 0.5 and 2.5 pmol were estimated for the positive and negative analysis modes, respectively. This study points out the tight correlation existing between the chemical status of the nanostructure surface and the AuNW-assisted LDI-MS performance in terms of reproducibility of spectra, intensity of analyte ions and reduction of interferences.
已根据污染和清洁过程对金纳米线（AuNWs）的表面化学进行了系统评估。纳米材料的表面质量与其在低分子量分析物的无基质激光解吸电离质谱（LDI-MS）分析中的性能相关。通过光刻图案化的纳米线电沉积技术将AuNWs阵列沉积在载玻片上。然后使用X射线光电子能谱、扫描电子显微镜和原子力显微镜对AuNWs的表面化学成分和形态进行表征。对AuNWs进行了一系列众所周知的清洁程序，目的是为亮氨酸脑啡肽的LDI-MS检测制备性能最佳的表面，亮氨酸脑啡肽被选作摩尔质量低于1000 g/mol的模型分析物。在2 M硫酸中进行长时间循环伏安法，最重要的是进行5分钟的氧等离子体清洁，在参考化合物的更简单（无干扰）和更强的质谱图方面提供了最佳结果。分析物总是以钠加合物的形式电离，在正、负分析模式下，亮氨酸脑啡肽的检测限分别估计为0.5和2.5 pmol。这项研究指出了纳米结构表面的化学状态与AuNW辅助LDI-MS在光谱重现性、分析物离子强度和干扰减少方面的性能之间存在的紧密相关性。
