Institute of Analytical Chemistry, Department of Chemistry , Zhejiang University , Hangzhou 310058 , P. R. China.
Department of General Surgery, Sir Run Run Shaw Hospital, School of Medicine , Zhejiang University , Hangzhou 310016 , P. R. China.
ACS Appl Mater Interfaces. 2018 May 2;10(17):14389-14398. doi: 10.1021/acsami.8b00506. Epub 2018 Apr 20.
Nanostructured semiconductors are one of the most potent candidates for matrix-free laser desorption/ionization mass spectrometric (LDI-MS) analysis of low-molecular-weight molecules. Herein, the enhanced photoinduced electron transfer and LDI on the tip of a vertical silicon nanowire (SiNW) array were investigated. Theoretical simulation and LDI detection of indigo and isatin molecules in negative ion mode revealed that the electric field can be enhanced on the tip end of SiNWs, thereby promoting the energy and electron transfer to the analytes adsorbed on the tip of SiNWs. On the basis of this finding, a tip-contact sampling method coupled with LDI-MS detection was established. In this strategy, the tip of SiNWs can be regarded as microextraction heads for the sampling of molecules when they come in contact with analytes. Impression of skin, tissue, and pericarp on the vertical SiNW array can effectively transfer endogenous metabolites or exogenous substances onto the tip. Upon laser irradiation, the adsorbed molecules on the SiNW tip can be efficiently ionized and detected in negative ion mode because of the tip-enhanced electron transfer and LDI effect. We believe this work may significantly expand the application of LDI-MS in various fields.
纳米结构半导体是用于基质自由激光解吸/电离质谱（LDI-MS）分析低分子量分子的最有效候选材料之一。在此，研究了垂直硅纳米线（SiNW）阵列尖端的增强光致电子转移和 LDI。在负离子模式下靛蓝和靛基质分子的理论模拟和 LDI 检测表明，电场可以在 SiNW 尖端增强，从而促进能量和电子转移到吸附在 SiNW 尖端的分析物上。在此基础上，建立了一种尖端接触采样方法，并与 LDI-MS 检测相结合。在这种策略中，当 SiNW 与分析物接触时，SiNW 的尖端可以看作是用于采样分子的微萃取头。垂直 SiNW 阵列上的皮肤、组织和果皮的压痕可以有效地将内源性代谢物或外源性物质转移到尖端。激光照射时，由于尖端增强的电子转移和 LDI 效应，吸附在 SiNW 尖端的分子可以被有效地离子化并在负离子模式下检测到。我们相信这项工作可能会极大地扩展 LDI-MS 在各个领域的应用。
