Sudhir Putty-Reddy, Wu Hui-Fen, Zhou Zi-Cong
Department of Chemistry, Graduate Institute of Life Sciences, Tamkang University, Tamsui, Taiwan.
Anal Chem. 2005 Nov 15;77(22):7380-5. doi: 10.1021/ac051162m.
A novel technique, gold nanoparticle-assisted single-drop microextraction (SDME) combined with atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry (AP-MALDI-MS) for the identification of peptides has been described. The SDME of peptides from aqueous solution was achieved using gold nanoparticles prepared in toluene as the acceptor phase. A simple phenomenon of isoelectric point (pI) of the peptides has been utilized successfully to extract the peptides into a single drop of nanogold in toluene. After extraction, a single-drop nano gold solution was directly spotted onto the target plate with an equal volume of matrix, proportional, variant-cyanohydroxy cinnamic acid ( proportional, variant-CHCA) and analyzed in AP-MALDI-MS. The parameters, such as solvent selection, extraction time, agitation rate, and pH effect, were optimized for the SDME technique. Using this technique, in aqueous solution, the lowest concentration detected for Met- and Leu-enkephalin peptides was 0.2 and 0.17 microM, respectively. In addition, the application of this technique to obtain the signal for the selected peptides in a mass spectrum in the presence of matrix interferences such as 1% Triton X-100 and 6.5 M urea has been showed. The application was extended to identify the peptides spiked into urine.
本文描述了一种用于肽类鉴定的新技术，即金纳米颗粒辅助单滴微萃取（SDME）与常压基质辅助激光解吸/电离质谱（AP-MALDI-MS）联用。使用甲苯中制备的金纳米颗粒作为接受相，实现了从水溶液中对肽的单滴微萃取。成功利用了肽的等电点（pI）这一简单现象，将肽萃取到甲苯中的单滴纳米金中。萃取后，将单滴纳米金溶液与等体积的基质、比例可变的氰基羟基肉桂酸（比例可变-CHCA）直接点样到靶板上，并在AP-MALDI-MS中进行分析。对单滴微萃取技术的参数，如溶剂选择、萃取时间、搅拌速率和pH效应进行了优化。使用该技术，在水溶液中，检测到的甲硫氨酸脑啡肽和亮氨酸脑啡肽的最低浓度分别为0.2和0.17 microM。此外，还展示了该技术在存在基质干扰（如1% Triton X-100和6.5 M尿素）的情况下，用于在质谱中获得所选肽信号的应用。该应用扩展到了鉴定掺入尿液中的肽。
