基于激光烧蚀-碳纤维电晕放电的原位电离质谱离子源

Ambient Ionization Mass Spectrometry Based on Laser Ablation-Carbon Fiber Corona Discharge Ionization

  • 摘要: 脂质分子在众多生理过程中扮演着重要角色,基于质谱的脂质组学分析手段在揭示脂质分子互作、疾病发生发展以及机体代谢异常方面具有重要作用。然而,受限于传统离子源的离子化方式,脂质组学的主要研究目标为磷脂类化合物,缺乏对中、低极性脂质化合物的系统研究。基于大气压化学电离的离子化技术可以拓宽脂质组学的覆盖范围。本研究提出了一种激光烧蚀-碳纤维电晕放电的原位电离质谱离子源,可以在原位条件下有效地分析固醇类化合物。利用该离子源共鉴定出13类(共计49种)皮肤表面脂肪化合物以及23种小鼠肝脏代谢物,并绘制了小鼠肝脏中6种具有代表性的脂质空间分布图谱,揭示了肝脏组织中存在包含能量转化、信号传递以及局部病理等在内的生物过程。

     

    Abstract: Metabolites are the regulated end products present in cells, tissues, or organisms. As an important class of metabolites in living organisms, lipids play critical roles in numerous biological processes. Lipids not only constitute the main components of cellular membranes and serve as energy storage substances, but also participate in disease development, cancer progression, and the maintenance of body homeostasis in the form of signaling messengers and immunomodulators. Therefore, obtaining comprehensive and accurate information on lipid composition, abundance, and spatial distribution networks is of significant practical importance for elucidating their biological functions, discovering potential disease biomarkers, and understanding pathological mechanisms. Mass spectrometry (MS), owing to its high sensitivity, high throughput, and high resolution, is widely employed in metabolomics or lipidomics. MS-based lipidomics approaches play a vital role in revealing lipid-molecule interactions, disease progression, and metabolic dysregulation. The ion source is often regarded as the heart of the mass spectrometer. The efficient ionization of target analytes is a prerequisite for MS analysis, and the characteristics of the ion source also significantly influence the accuracy, reproducibility, and reliability of MS determination. Current lipidomics research predominantly focuses on the analysis of phospholipids, which are abundant in cells and readily ionizable, whereas systematic investigations into other moderately to low-polarity lipids with important physiological activities remain insufficient. Ionization techniques based on atmospheric pressure chemical ionization (APCI) enable the effective ionization of low-polarity compounds. The APCI ionization mechanism can be summarized as gas-phase chain reactions mediated by excited reactive species, achieving analyte ionization through processes such as proton transfer, Penning ionization, and charge exchange. Sample pretreatment procedures also significantly affect the throughput and efficiency of mass spectrometry analysis. Ambient ionization mass spectrometry allows for the effective detection of target analytes while simplifying pretreatment procedures, extending the interdisciplinary application scope of mass spectrometry. In this study, an ambient ion source based on laser ablation-carbon fiber corona discharge (LACFCD) was developed. The ion source consists of a laser desorption module and a post-ionization module based on carbon fiber corona discharge. Laser ablation-carbon fiber corona discharge mass spectrometry (LACFCD-MS) obviates the need for complex pretreatment procedures, enabling rapid identification of lipids on the skin surface. A total of 13 categories (49 species) of lipids were identified, including triglycerides, long-chain fatty acids, long-chain fatty alcohols, very-long-chain fatty acids, cholesterol and its derivatives, and eicosanoid precursors, demonstrating promising potential for high-throughput and rapid screening applications. Furthermore, the spatial metabolomics data from mouse liver tissue were acquired using LACFCD-MS. The spatial distribution maps of 23 lipid species in mouse liver tissue were obtained, revealing the biological processes including energy conversion, signal transduction, and localized pathology. This demonstrates its potential for resolving tissue spatial metabolic heterogeneity, correlating morphology with molecular function, and discovering potential pathological subregion biomarkers. This study also has certain limitations. Primarily, it did not achieve direct in-situ detection of skin surface lipids, requiring the use of copper-coated glass slides as intermediate sample carriers. Future integration with diverse sample desorption modules may enable real-time, in-situ lipidomics analysis. Additionally, the exploration of molecular interaction patterns in spatial lipidomics was incomplete, as a comprehensive assessment of the interactions among different lipid molecules and their corresponding physiological significance was not conducted.

     

/

返回文章
返回