Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging of Tissues via the Formation of Reproducible Matrix Crystals by the Fluorescence-Assisted Spraying Method: A Quantification Approach
Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging of Tissues via the Formation of Reproducible Matrix Crystals by the Fluorescence-Assisted Spraying Method: A Quantification Approach
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DOI：
10.1021/acs.analchem.1c03369
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发表时间：
2022-01-18
影响因子：
7.4
通讯作者：
Tanaka，Mitsuru
中科院分区：
文献类型：
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作者：
Hahm，Tae Hun;Matsui，Toshiro;Tanaka，Mitsuru
基质辅助激光解吸/电离质谱（MALDI-MS）成像定量分析的应用受到组织中不可重现基质晶体中分析物MS强度变化的限制。为了克服这一挑战，荧光辅助喷雾方法开发了一个恒定的基质量，采用MS可检测的荧光试剂，罗丹明6 G（R6 G），这是喷雾与基质。为了在组织切片上形成均匀的基质晶体，喷雾含有R6 G（40 μg/mL）和O-二硝基苯（O-DNB，10 mg/mL）的基质溶液1，5-二氨基萘（10 mg/mL），直到达到所需的恒定荧光强度。与常规固定循环数喷雾法测定结果[相对标准偏差（RSD）= 31.1%]相比，荧光辅助基质喷雾法显著提高了分析物[阿魏酸（FA），RSD = 3.1%]对R6 G的相对质谱强度的重现性。结果表明，R6 G可作为基质量的指标和MS归一化标准。所提出的基质喷雾成功地定量了大鼠肾脏切片中的硝苯地平（0.5-40 pmol/mm 2，阳性模式，R2= 0.965）和FA（0.5-75 pmol/mm 2，阴性模式，R2= 0.9972）。采用定量MALDI-MS成像分析，经口给予50 mg/kg后，在大鼠肾脏中蓄积的FA在15、30和60 min时分别为3.5、3.0和0.2 μmol/g组织。
The application of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) imaging to quantitative analyses is restricted by the variability of MS intensity of the analytes in nonreproducible matrix crystals of tissues. To overcome this challenge, a fluorescence-assisted spraying method was developed for a constant matrix amount employing an MS-detectable fluorescent reagent, rhodamine 6G (R6G), which was sprayed with the matrix. To form a homogeneous matrix crystal on the tissue section, a matrix solution, 1,5-diaminonaphthalene (10 mg/mL), containing R6G (40 μg/mL) andO-dinitrobenzene (O-DNB, 10 mg/mL) was sprayed until the desired constant fluorescence intensity was achieved. Compared with that obtained via conventional cycle-number-fixed spraying [relative standard deviation (RSD) = 31.1%], the reproducibility of the relative MS intensity of the analyte [ferulic acid (FA), RSD = 3.1%] to R6G was significantly improved by the fluorescence-assisted matrix spraying. This result indicated that R6G could be employed as an index of the matrix amount and an MS normalizing standard. The proposed matrix spraying successfully quantified nifedipine (0.5–40 pmol/mm2in the positive mode,R2= 0.965) and FA (0.5–75 pmol/mm2in the negative mode,R2= 0.9972) in the kidney section of a rat. Employing the quantitative MALDI-MS imaging assay, FA, which accumulated in the kidney of the rat after 50 mg/kg was orally administered, was visually determined to be 3.5, 3.0, and 0.2 μmol/g tissue at 15, 30, and 60 min, respectively.