Application advances of mass spectrometry imaging technology in environmental pollutants analysis and their toxicity research

质谱成像技术在环境污染物分析及毒性研究中的应用进展

人类多数疾病的发生是由环境和基因因素共同驱动,超过70%的疾病与环境污染有关。明确环境污染暴露与人体健康及特定疾病间的因果关系,锁定关键风险因子,有助于疾病的精准防控。重金属、颗粒物和有机污染物等的暴露从妊娠期开始贯穿整个生命周期,可通过呼吸、饮食、皮肤接触和母婴传递等途径进入体内,并对健康产生潜在威胁。

Most human diseases are driven by both environmental and genetic factors, and more than 70 per cent of diseases are related to environmental pollution. Clarifying the causal relationship between exposure to environmental pollution and human health and specific diseases, and targeting key risk factors, can help in the precise prevention and control of diseases.

Exposure to heavy metals, particulate matter and organic pollutants occurs throughout the life cycle from pregnancy onwards, and can enter the body through respiration, diet, skin contact and mother-to-child transmission, posing a potential threat to health.

污染物对健康的影响十分复杂,进入体内后由血液或其他体液转送到机体各个组织和器官,进行代谢和蓄积,通过与多种生物分子相互识别和交互作用而产生毒性效应。阐明外源性污染物在生物体内和特定器官微区中的分布特征及暴露引发的毒性效应是环境毒理学研究的重要内容。

The health effects of pollutants are very complex. After entering the body, they are transported by blood or other body fluids to various tissues and organs, metabolised and accumulated, and produce toxic effects through mutual recognition and interaction with various biomolecules.

Elucidating the distribution characteristics of exogenous pollutants in organisms and specific organ microregions and the toxic effects induced by exposure is an important part of environmental toxicology research.

除了常规毒理学手段,组学技术也是目前解析污染物毒性效应的有力工具。内源性代谢物不仅可以放大相关基因和蛋白质的变化,还可作为调节剂直接调控生理过程和表型,定量描述代谢物变化的代谢组学技术已被用于多种环境污染物的毒性效应、作用机制和生物标志物研究中。

In addition to conventional toxicological tools, histological techniques are now a powerful tool for analysing the toxic effects of pollutants. Endogenous metabolites can not only amplify the changes of related genes and proteins, but also act as regulators to directly regulate physiological processes and phenotypes, and metabolomics, which quantitatively describes the changes of metabolites, has been used in the study of the toxic effects, mechanisms of action, and biomarkers of a variety of environmental pollutants.

常用的正电子发射断层扫描(PET)、磁共振成像(MRI)、荧光成像和拉曼成像等分子成像技术具有高灵敏度、高分辨率、实时性和非侵入性等优势,但难以在无标记的基础上同时实现组织中数百种及以上化合物的可视化分析。

Commonly used molecular imaging techniques such as PET, MRI, fluorescence imaging and Raman imaging have the advantages of high sensitivity, high resolution, real-time and non-invasive, but it is difficult to achieve the visual analysis of hundreds of compounds and more in tissues on a label-free basis.

质谱技术是污染物和内源性代谢物定性和定量分析最主要的技术手段。常规分析时需将生物样品和组织匀浆处理以获得丰富的分子信息,但此操作会导致待测物的空间信息丢失。应运而生的激光显微切割技术通过对特定位置细胞和组织进行取样而保留待测物的空间位置信息,是目前空间多组学分析的关键技术,但后续生物分子的空间分布重构较为复杂。

Mass spectrometry (MS) is the most important technique for the qualitative and quantitative analysis of contaminants and endogenous metabolites. Conventional analyses require the homogenisation of biological samples and tissues to obtain rich molecular information, but this operation results in the loss of spatial information about the object to be measured.

Laser microdissection is a key technique for spatial multi-omics analyses because it preserves the spatial location information of the analytes by sampling cells and tissues at specific locations, but the subsequent reconstruction of the spatial distribution of the biomolecules is more complicated.

质谱成像技术(mass spectrometry imaging, MSI)是一种基于质谱分析的新型分子影像技术,能够直接扫描生物组织切片,从而获得大量已知或未知内源性和外源性化合物(如小分子代谢物、蛋白质、多肽、脂质和药物等)的化学结构、相对含量和空间分布信息。本文基于不同MSI技术原理和特点,系统综述了MSI技术在环境污染物分析和代谢毒性效应解析方面的应用进展。

Mass spectrometry imaging (MSI) is a novel molecular imaging technique based on mass spectrometry analysis, which can directly scan biological tissue sections to obtain the chemical structure, relative content and spatial distribution of a large number of known or unknown endogenous and exogenous compounds (e.g., small molecule metabolites, proteins, peptides, lipids, and drugs). Based on the principles and characteristics of different MSI techniques, this paper presents a systematic review of the progress in the application of MSI techniques in the analysis of environmental pollutants and metabolic toxicity effects.

1 质谱成像技术概述

Overview of mass spectrometry imaging techniques

1.1 MSI技术原理

Principles of MSI technology

MSI技术是一种以质谱为基础的表征离体组织和细胞中元素和化合物空间分布的免标记影像技术。通过一个聚焦的电离源(如离子枪、激光、分子束等)直接扫描样品使其表面分子解吸离子化,通过质量分析器检测各个像素点的质荷比(m/z)和离子强度,最终由成像软件结合质谱数据和位置信息对待测物的空间分布进行重构和可视化。该技术可提供生物整体、组织微区、单细胞或亚细胞尺度待测物的定性、相对定量和定位信息

MSI is a label-free imaging technique based on mass spectrometry for characterising the spatial distribution of elements and compounds in isolated tissues and cells. A focused ionisation source (e.g., ion gun, laser, molecular beam, etc.) directly scans the sample to desorb and ionise molecules on the surface, and a mass analyser detects the mass-to-charge ratio (m/z) and ion intensity at each pixel, and the spatial distribution of the object to be measured is reconstructed and visualised by the imaging software in conjunction with the mass spectrometry data and the positional information. The technique provides qualitative, relative quantitative and localisation information of the object to be measured at the whole organism, tissue microregion, single cell or subcellular scale.

1.2 常用质谱成像技术类型

Types of commonly used mass spectrometry imaging techniques

目前常用MSI技术根据离子化方式的不同可分为(matrix assisted laser desorption ionization mass spectrometry imaging, MALDI-MSI)、(desorption electrospray ionization mass spectrometry imaging, DESI-MSI)、(secondary ion mass spectrometry imaging, SI-MSI)和(laser ablation inductively coupled plasma mass spectrometry imaging, LA-ICP-MSI)等。这些技术在适用分析对象和空间分辨率等方面各具特点

Currently commonly used MSI techniques can be divided into (matrix-assisted laser desorption ionisation mass spectrometry imaging, MALDI-MSI), (desorption electrospray ionisation mass spectrometry imaging, DESI-MSI), (secondary ion mass spectrometry imaging, SI-MSI), and (laser ablation inductively coupled plasma mass spectrometry imaging, SI-MSI), which have their own characteristics in terms of applicable analytical objects and spatial resolution. Each of these techniques has its own characteristics in terms of applicability to the analysed object and spatial resolution.

1.2.1 MALDI-MSI技术

MALDI-MSI technology

MALDI-MSI是目前应用最广泛的MSI技术,通过激光束照射基质喷涂过的样品表面,基质吸收激光能量并传递给待测物使其解吸与离子化,适用于生物样本表面代谢物、多肽、蛋白质和药物等化合物的可视化分析。除了激光激发波长和强度外,基质选择对于MALDI离子化效率至关重要。

MALDI-MSI is currently the most widely used MSI technique for the visualisation of compounds such as metabolites, peptides, proteins and drugs on the surface of biological samples by irradiating the surface of the sample sprayed by a laser beam, and the matrix absorbs the laser energy and transmits it to the object to be measured for desorption and ionisation. In addition to the laser excitation wavelength and intensity, the choice of substrate is crucial for MALDI ionisation efficiency.

常用基质包括2,5-二羟基苯甲酸(DHB)、α-氰基-4-羟基肉桂酸和芥子酸等,但它们存在背景峰干扰高、选择性弱和相对分子质量较低的化合物电离效率低等问题。

Commonly used substrates include 2,5-dihydroxybenzoic acid (DHB), α-cyano-4-hydroxycinnamic acid and erucic acid, etc. However, they suffer from the problems of high interference of background peaks, weak selectivity, and low ionisation efficiency for compounds with low relative molecular mass.

1.2.2 DESI-MSI技术

DESI-MSI technology

DESI-MSI是一种常压常温、敞开式MSI技术,高速雾化气带动溶剂在高电压下形成电喷雾,直接吹扫样品表面溅射出含待测物的次级带电液滴束,溶剂快速蒸发将电荷转移给待测物并使其形成气态离子,通过离子传输管进入质量分析器。成像效果与电喷雾溶剂组成和流速有关,会影响样品表面待测物的溶解度、扩散性和离子化效率,主要用于分子质量2000 Da以下化合物的分析。

DESI-MSI is an open-type MSI technique at ambient pressure and temperature. High-speed atomised gas drives the solvent to form an electrospray at high voltage, which directly sweeps the sample surface to sputter a secondary beam of charged droplets containing the substance to be measured. The solvent evaporates rapidly to transfer the charge to the substance to be measured and form gaseous ions, which are fed into the mass analyser through an ion transfer tube. The imaging effect is dependent on the composition of the electrospray solvent and the flow rate, which affects the solubility, diffusivity and ionisation efficiency of the material to be measured on the surface of the sample, and is mainly used for the analysis of compounds with molecular masses up to 2000 Da.

成像空间分辨率受喷雾装置限制,喷嘴与样品表面和质谱进样口间的距离和角度对空间分辨率和信号强度影响极大。现有商业仪器空间分辨率为20 μm,对于大面积生物样品和非生物样品中化合物成像分析独具优势。

The spatial resolution of imaging is limited by the spray device, and the distance and angle between the nozzle and the sample surface and the mass spectrometry inlet have a great influence on the spatial resolution and signal intensity. The spatial resolution of existing commercial instruments is 20 μm, which is advantageous for imaging compounds in large biological and non-biological samples.

1.2.3 SI-MSI技术

SI-MSI technology

SI-MSI技术可用于元素和分子质量小于1000 Da的疏水性化合物的可视化分析,是目前空间分辨率最高的MSI技术。在高真空环境下,利用聚焦的高能初级离子束轰击样品表面,产生次级离子进入质量分析器进行分析,已被用于地球科学、材料科学和生命科学等领域。

The SI-MSI technique can be used for the visual analysis of elements and hydrophobic compounds with molecular masses less than 1000 Da, and is the MSI technique with the highest spatial resolution. Under high vacuum, a focused high-energy primary ion beam is used to bombard the sample surface, generating secondary ions that enter the mass analyser for analysis, which has been used in the fields of earth science, material science and life science.

1.2.4 LA-ICP-MSI技术

LA-ICP-MSI technique

与前三者技术不同,LA-ICP-MSI技术发展最早且最为成熟,主要用于元素可视化分析。通过将激光束聚焦于样品表面使微区样品熔蚀气化,由载气将样品微粒送至等离子体中进行原子化并电离,最后进入质量分析器进行检测,具有分析速度快、进样效率高、可进行多元素同时分析并提供同位素信息的优势。自2003年首次被用于表征羊肝脏组织中Cu的分布后,LA-ICP-MSI技术开始被广泛用于生命科学领域中的元素成像分析近年来,将LA-ICP-MS技术与免疫组织化学技术相结合的质谱流式成像系统可在单细胞层面实现数十个蛋白质和其他生物分子的成像分析,扩大了可检测目标物范围。

Unlike the first three techniques, LA-ICP-MSI is the earliest and most mature technique, mainly used for elemental visualisation. By focusing a laser beam on the sample surface to melt and vaporise the micro-area sample, the sample particles are sent to the plasma by the carrier gas for atomisation and ionisation, and finally enter the mass analyser for detection, which has the advantages of fast analysis speed, high injection efficiency, simultaneous analysis of multi-elements and provision of isotopic information.

Since 2003, when LA-ICP-MSI was firstly used to characterize the distribution of Cu in sheep liver tissue, it has been widely used for elemental imaging in life sciences. In recent years, mass spectrometry (MS) flow imaging systems combining LA-ICP-MS and immunohistochemistry can image dozens of proteins and other biomolecules at the single-cell level, which can expand the range of detectable targets. The target range has been enlarged.

1.2.5 其他技术

Other technologies

随着离子化技术的革新,一系列解吸/后电离和等离子体新型电离技术不断出现。空气动力辅助离子源(AFAI-DESI)利用空气流实现大气压中离子或带电液滴的远距离传输,在质谱入口富集带电液滴,提高了离子化效率,并扩展了待测样品的应用空间。
With the innovation of ionisation technology, a series of new ionisation techniques for desorption/post-ionisation and plasma have emerged. The aerodynamic assisted ion source (AFAI-DESI) uses air flow to achieve long-distance transport of ions or charged droplets at atmospheric pressure and enrichment of charged droplets at the entrance of the mass spectrometer, which improves the ionisation efficiency and extends the application space of the samples to be tested.

激光消融电喷雾电离源通过先将待测物激光消融解吸后再进行电喷雾离子化,可进行大分子质谱化合物的成像分析。介质阻挡放电电离源通过在两个放电电极之间放置绝缘介质,施加交流电压使两电极间的惰性气体或混合气体电离形成稳定低温等离子体,并对载体上的待测物进行解吸和离子化。低温等离子体电离源则是利用气体(He、Ar或空气)在电场放电作用下产生的低温等离子体喷射样品表面使待测化合物解吸并离子化。这些离子化技术在检测目标物类别、空间分辨率、电离效率、稳定性和灵敏度等方面得到了不同程度的提升和改进。

The laser ablation electrospray ionisation source can be used to image large molecules for mass spectrometry by first desorbing the object to be measured by laser ablation and then carrying out electrospray ionisation. Dielectric barrier discharge ionisation source by placing an insulating medium between two discharge electrodes, applying an AC voltage to ionise an inert gas or a gas mixture between the two electrodes to form a stable low-temperature plasma, and desorb and ionise the material to be measured on the carrier. The low-temperature plasma ionisation source uses low-temperature plasma generated by gas (He, Ar or air) under the action of electric field discharge to spray the sample surface to desorb and ionise the compound to be measured. These ionisation techniques have been enhanced and improved to varying degrees in terms of target class, spatial resolution, ionisation efficiency, stability and sensitivity.

1.3 常见MSI质量分析器

Common MSI quality analysers

质量分析器是成像质谱仪的核心组成部分,高质量分辨率和质量精度是进行化合物准确注释的必要条件。MSI技术多采用高分辨质量分析器。飞行时间质谱仪(TOF MS)因灵敏度高、分析速度快、可同时检测多个分子且理论上无质量检测上限,成为MSI技术最常用的质量分析器。近年来,离子淌度技术因对结构类似物和同分异构体的分离能力强在MSI系统中表现出独特优势,显著提高了化合物的鉴定准确性和成像精度,尤其在脂质组可视化分析方面。近日,研究者将淌度分离后的母离子不经质量隔离而完全碎裂并进行非依赖数据采集,结合智能谱图解卷积算法实现了多种脂质的结构解析和组织空间分布可视化,在不增加成像分析时间的情况下显著提升了脂质组结构解析能力。

The mass analyser is the core component of an imaging mass spectrometer, and high mass resolution and mass accuracy are essential for accurate compound annotation.MSI technology mostly adopts high-resolution mass analysers. The time-of-flight mass spectrometer (TOF MS) is the most commonly used mass analyser for MSI because of its high sensitivity, fast analysis speed, simultaneous detection of multiple molecules, and the theoretical absence of upper limit of mass detection. In recent years, the ion mobility technique has demonstrated unique advantages in MSI systems due to its ability to separate structural analogues and isomers, which significantly improves the identification accuracy and imaging precision of compounds, especially in the visualisation of the lipidome. Recently, the researcher has completely fragmented the parent ions after the flow separation without mass isolation and performed non-dependent data acquisition, combined with the intelligent spectral deconvolution algorithm to achieve the structural analysis of various lipids and visualisation of the tissue spatial distribution, which significantly improved the structural analysis of the lipid group without increasing the time of the imaging analysis.

1.4 质谱成像技术分析流程

Mass spectrometry imaging technique analysis process

MSI分析工作流程为样品制备-质谱数据采集-数据处理与可视化分析。以小鼠肾脏组织成像为例,首先收集新鲜肾脏组织立即冷冻,冰冻切片(厚度5~20 μm),并进行切片预处理;以网格划分模式进行质谱分析获得各像素点质谱图,经数据预处理后进行鉴定、统计分析和可视化。

The workflow of MSI analysis was sample preparation, mass spectrometry data acquisition, data processing and visual analysis. Taking mouse kidney tissue imaging as an example, fresh kidney tissue was collected and frozen immediately, and frozen sections (thickness of 5~20 μm) were prepared; MSI was performed in a gridding mode to obtain the mass spectrometry of each pixel, and then identified, statistically analysed and visualized after data preprocessing.

维持组织形态不变和组织完整性对物质分子信号强度和定位十分重要,同时组织切片操作和保存不当也会导致表面分子降解移位影响质谱成像的准确性和真实性。数据采集质量取决于成像质谱仪的性能,根据需求选择离子化技术,高分辨率和高精度质量分析器是分子鉴定的必要条件。但是低极性、难电离物质分子是MSI可视化分析的难点。

Maintaining the morphology and integrity of the tissue is important for the signal intensity and localisation of the molecules, while improper handling and storage of tissue sections can lead to the degradation and displacement of molecules on the surface, affecting the accuracy and authenticity of the mass spectrometry imaging. The quality of data acquisition depends on the performance of the imaging mass spectrometer, and the choice of ionisation technique, high resolution and high precision mass analyser are essential for molecular identification. However, low polarity and difficult to ionise molecules are the difficulties in MSI visualisation and analysis.

2 质谱成像技术在环境污染物分析研究中的进展

Advances in mass spectrometry imaging for the analysis of environmental pollutants

外源性的污染物进入生物体内后会分布到全身各个组织和器官,在不同组织和器官中的代谢速度和累积量不同。生物体内污染物分布特征描述和量化是环境毒理学研究的重要内容。MSI技术已被用于模式动物和植物中多种重金属、颗粒物和有机污染物的可视化分析

Exogenous pollutants are distributed to tissues and organs throughout the body, and their metabolic rate and accumulation in different tissues and organs are different. The characterisation and quantification of the distribution of pollutants in organisms is an important part of environmental toxicology, and the MSI technique has been used to visualise and analyse a wide range of heavy metals, particulate matter and organic pollutants in model animals and plants.

2.1 重金属

重金属是一类重要的环境污染物,进入体内后不易被排出。

2.1 Heavy metals

Heavy metals are an important class of environmental pollutants that are not easily excreted from the body.

2.2 颗粒物

日常生活环境中存在着大量的颗粒物,如PM2.5和人造纳米颗粒等。

2.2 Particulate matter

A large amount of particulate matter, such as PM2.5 and man-made nanoparticles, exists in the everyday environment.

2.3 有机污染物

有机污染物种类繁多,大多数具有生物累积性和持久性。此外,MSI技术还被用来解析植物中农药的迁移规律。

2.3 Organic pollutants

There is a wide variety of organic pollutants, most of which are bioaccumulative and persistent. In addition, the MSI technique has been used to analyse the migration patterns of pesticides in plants.

总体来说,MSI技术可绘制外源性环境污染物在生物组织中的空间分布特征,为污染物的毒代动力学和植体内迁移规律研究提供了更为直接的证据。与重金属成像分析相比,生物组织中有机污染物的离子化效率低,目前商业化成像仪器仅可对少量有机污染物进行可视化分析。

In general, MSI can map the spatial distribution of exogenous environmental pollutants in biological tissues, providing more direct evidence for toxicokinetic and intra-plant transport studies of pollutants. Compared with heavy metal imaging, the ionisation efficiency of organic pollutants in biological tissues is low, and only a small number of organic pollutants can be visualised by commercial imaging instruments.

3 质谱成像技术在环境污染物毒性效应研究中的进展

Progress of mass spectrometry imaging in the study of toxic effects of environmental pollutants

3.1 MSI技术用于模式生物中内源性代谢物的空间分布特征研究

3.1 MSI techniques for characterising the spatial distribution of endogenous metabolites in model organisms

环境污染物毒性效应研究常选与人类基因高度相似的模式生物进行暴露实验,包括大小鼠和斑马鱼等,基于MSI的空间代谢组学技术可用于这些模式生物整体或特定组织中代谢物的可视化分析。采用相关技术绘制的脑组织中不同微区间的代谢网络图谱显示，脑组织中脂质也具有特异的微区分布特征。此外,研究者们也采用MSI技术建立了特定脂质与大型溞、昆虫等模式生物解剖特征的关联性。

Toxic effects of environmental pollutants are often studied by selecting model organisms with high similarity to human genes for exposure experiments, including rats, mice and zebrafish, etc. Spatial metabolomics techniques based on MSI can be used for the visualisation and analysis of metabolites in the whole or in specific tissues of these model organisms. Metabolic network mapping of different micro compartments in brain tissues using the related technology showed that lipids in brain tissues also have specific micro compartmental distribution characteristics. In addition, the researchers also used the MSI technique to establish the correlation between specific lipids and anatomical features of model organisms such as Daphnia magna and insects.

3.2 MSI技术在环境污染物毒性效应研究中的应用

3.2 Application of MSI techniques in the study of toxic effects of environmental pollutants

环境污染物暴露会引起生物体内生物学过程受损,对结构复杂且异质性的靶器官和效应器官的毒性效应和机制更为复杂。基于MSI技术的空间代谢组学已被用于环境污染物毒性效应、作用机制和暴露生物标志物研究中

Exposure to environmental pollutants causes impairment of biological processes in organisms, and the toxic effects and mechanisms on target and effector organs, which are structurally complex and heterogeneous, are even more complex. Spatial metabolomics based on MSI technology has been used to study the toxic effects of environmental pollutants, mechanisms of action and biomarkers of exposure

总体来看,与代谢组学技术相比,基于MSI技术的空间代谢组学可原位表征生物体对污染物暴露的代谢应答情况,尤其是在小体型模式生物和异质性的组织和器官中。MSI技术为外源性污染物毒性效应研究开辟了新视角,通过与常规毒理学技术或其他组学技术相结合可对污染物毒性进行全面解读。

In general, compared with metabolomics, spatial metabolomics based on MSI technology can characterise the metabolic response of organisms to pollutant exposure in situ, especially in small model organisms and heterogeneous tissues and organs.MSI technology opens up new perspectives in the study of exogenous pollutant toxicity effects, which can be comprehensively interpreted in conjunction with conventional toxicological techniques or other histological techniques. The MSI technique opens up a new perspective for the study of toxic effects of exogenous pollutants.

4 结论与展望

4 Conclusion and outlook

MSI技术在环境污染物分析及毒性效应研究中发挥着重要作用,主要用来提供外源性污染物和内源性代谢物在模式生物全身和特定组织中的含量和空间分布信息。不同离子化技术的工作原理、适用分析对象和成像空间分辨率等不同。采用MSI技术原位解析模式生物体内污染物的毒代动力学与代谢应答的毒性效应研究,有助于阐明污染物的毒性效应与作用机制,发现暴露生物标志物。

MSI techniques play an important role in the analysis of environmental pollutants and toxicity effects, and are mainly used to provide information on the content and spatial distribution of exogenous pollutants and endogenous metabolites in the whole body and specific tissues of model organisms. Different ionisation techniques have different working principles, applicability and spatial resolution. The in situ analysis of toxicokinetics and metabolic response of pollutants in model organisms by MSI can help to elucidate the toxic effects and mechanisms of pollutants and identify biomarkers of exposure.

尽管MSI技术表现出了独特的原位可视化分析的优势,但对于低含量、难电离的有机污染物和内源性代谢物的分析效果不佳。而且MSI技术本身也存在可重复性较差、数据采集时间长、化合物注释和鉴定难等问题。为此,迫切需要研发能够兼顾高分辨率和成像速度的新型高灵敏度的成像质谱,开发先进的质谱成像软件和海量数据的挖掘系统。此外,发展多模态成像技术,将MSI与其他分子成像技术和空间组学技术相结合,以最大限度地获取化学和生物信息,全面解析污染物的毒性。随着MSI成像技术的不断发展和完善,必将进一步推动环境污染物分析及毒理学研究,极大地拓展其应用领域。

Although the MSI technique has demonstrated unique advantages for in situ visual analysis, it is not effective for the analysis of low content, difficult to ionise organic pollutants and endogenous metabolites. Moreover, the MSI technique itself has problems such as poor reproducibility, long data acquisition time, and difficulty in compound annotation and identification. In this regard, there is an urgent need to develop a new type of highly sensitive imaging mass spectrometry that can take into account both high resolution and imaging speed, and to develop advanced mass spectrometry imaging software and massive data mining system. In addition, the development of multimodal imaging technology, the combination of MSI with other molecular imaging technologies and spatial genomics technology, in order to maximise the acquisition of chemical and biological information, comprehensive analysis of the toxicity of pollutants. With the continuous development and improvement of MSI imaging technology, it will further promote the analysis of environmental pollutants and toxicological research, and greatly expand its application fields.