Department of Physics, National Dong Hwa University, Shoufeng, Hualien, 97401, Taiwan.
AcroMass Technologies Inc., Hukou, Hsinchu, 30352, Taiwan.
Talanta. 2023 Jul 1;259:124555. doi: 10.1016/j.talanta.2023.124555. Epub 2023 Apr 15.
Detecting megadalton matrix-assisted laser desorption/ionization (MALDI) ions in an ion trap mass spectrometer is a technical challenge. In this study, megadalton protein and polymer ions were successfully measured by MALDI linear ion trap mass spectrometer (LIT-MS) for the first time. The LIT-MS is comprised of a Thermo linear ion trap mass analyzer and a highly sensitive charge-sensing particle detector (CSPD). A newly designed radio frequency (rf) scan mode with dipolar resonance ejection techniques is proposed to extend the mass range of LIT-MS up to one million Thomson (Th). We analyze high mass ions with mass-to charge (m/z) ratios ranging from 100 kTh to 1 MTh, including thyroglobulin, alpha-2-macroglobulin, immunoglobulins (e.g., IgG and IgM), and polymer (∼ 940 kTh) ions. Besides, it is also very challenging for ion trap mass spectrometry to detect megadalton ions at low concentrations. By adopting high affinity carboxylated/oxidized detonation nanodiamonds (oxDNDs) to enrich IgM molecules and form antibody-nanodiamond conjugates, we have successfully reached ∼ 5 nM (5 μg/mL) concentration which is better than that by the other techniques.
在离子阱质谱仪中检测兆道尔顿基质辅助激光解吸/电离（MALDI）离子是一项技术挑战。在这项研究中，兆道尔顿蛋白质和聚合物离子首次成功地通过 MALDI 线性离子阱质谱仪（LIT-MS）进行了测量。LIT-MS 由 Thermo 线性离子阱质谱分析仪和高灵敏度的电荷感应颗粒探测器（CSPD）组成。提出了一种新设计的射频（rf）扫描模式，具有偶极共振喷射技术，将 LIT-MS 的质量范围扩展到一百万汤姆逊（Th）。我们分析了质量荷比（m/z）比值从 100 kTh 到 1 MTh 的高质量离子，包括甲状腺球蛋白、α-2-巨球蛋白、免疫球蛋白（如 IgG 和 IgM）和聚合物（约 940 kTh）离子。此外，离子阱质谱仪在低浓度下检测兆道尔顿离子也极具挑战性。通过采用高亲和力的羧基化/氧化爆轰纳米金刚石（oxDND）来富集 IgM 分子并形成抗体-纳米金刚石缀合物，我们已经成功地达到了约 5 nM（5 μg/mL）的浓度，优于其他技术。
