Department of Materials and Science and Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul03722, Republic of Korea.
Korea Institute of Science and Technology (KIST), Seoul02792, Republic of Korea.
ACS Nano. 2022 Nov 22;16(11):18284-18297. doi: 10.1021/acsnano.2c05993. Epub 2022 Oct 20.
Nanostructures─coupled with mass spectrometry─have been intensively investigated to improve the detection sensitivity and reproducibility of small biomolecules in laser desorption/ionization mass spectrometry (LDI-MS). However, the impact of laser-induced shock wave on the ionization of the nanostructures has rarely been reported. Herein, we systematically elucidate the laser shock wave effect on the ionization in terms of the development of atomic defects and piezoelectricity in two-dimensional graphitic carbon nitride nanosheets (g-CN NS) by short laser pulses. The mass analysis results of immunosuppressive drugs verify the enhanced LDI-MS performance, structurally originating from anisotropic lattice distortions in g-CN NS, i.e., in-plane extension (contraction) and out-of-plane contraction (extension) that modulate the charge carrier motion. Along with the experimental investigations, density functional theory calculations on Mulliken charges and dipole moments demonstrate the contribution of defect and piezoelectricity to the ionization. The results of this study provide a mechanistic understanding of the underlying ionization processes, which is crucial for revealing the full potential of laser shock waves in LDI-MS.
纳米结构与质谱联用，已被广泛研究用于提高激光解吸/电离质谱（LDI-MS）中小生物分子的检测灵敏度和重现性。然而，激光诱导冲击波对纳米结构电离的影响却鲜有报道。在此，我们通过短激光脉冲，系统地阐明了二维石墨相氮化碳纳米片（g-CN NS）中原子缺陷和压电性的发展对激光冲击波作用下的电离的影响。免疫抑制剂的质谱分析结果验证了 LDI-MS 性能的增强，其结构源于 g-CN NS 的各向异性晶格畸变，即平面内拉伸（收缩）和平面外收缩（拉伸），从而调节载流子的运动。结合实验研究，Mulliken 电荷和偶极矩的密度泛函理论计算表明了缺陷和压电性对电离的贡献。本研究的结果提供了对基础电离过程的机械理解，这对于揭示激光冲击波在 LDI-MS 中的全部潜力至关重要。
