More than 50% of all known proteins are glycosylated, which is critical for many biological processes such as protein folding and signal transduction. Glycosylation has proven to be associated with different mammalian diseases such as breast and liver cancers. Therefore, characterization of glycans is highly important to facilitate a better understanding of the development and progression of many human diseases. Although matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS) offers several advantages such as ease of operation and short analysis times, however, due to the complexity of glycan structures and their low ionization efficiency, there are still challenges that need to be addressed to achieve sensitive glycan analysis. Here, magnetic carbon nanocomposites (CNPs@Fe₃O₄ NCs) were used as a new MALDI matrix or co-matrix for the analysis of glycans derived from different model glycoproteins and human blood serum samples. The addition of CNPs@Fe₃O₄ NCs to the matrix significantly enhanced glycan signal intensity by several orders of magnitude, and effectively controlled/reduced/eliminated in-source decay (ISD) fragmentation. The latter was attained by modulating CNPs@Fe₃O₄ NCs concentrations and allowed the simultaneous study of intact and fragmented glycans, and pseudo-MS³ analysis. Moreover, CNPs@Fe₃O₄ NCs was also effectively employed to desalt samples directly on MALDI plate, thus enabling direct MALDI-MS analysis of unpurified permethylated glycans derived from both model glycoproteins and biological samples. On-plate desalting enhanced sensitivity by reducing sample loss.

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超过 50% 的已知蛋白质被糖基化，这对于蛋白质折叠和信号转导等许多生物过程至关重要。糖基化已被证明与不同的哺乳动物疾病有关，例如乳腺癌和肝癌。因此，聚糖的表征对于促进更好地了解许多人类疾病的发生和进展非常重要。尽管基质辅助激光解吸电离质谱（MALDI-MS）具有操作简便、分析时间短等诸多优点，但由于聚糖结构复杂且电离效率低，仍然存在需要解决的挑战。解决这些问题以实现灵敏的聚糖分析。在这里，磁性碳纳米复合材料（CNPs@Fe ₃ O ₄ NCs）被用作新的MALDI基质或共基质，用于分析源自不同模型糖蛋白和人血清样品的聚糖。向基质中添加CNP@Fe ₃ O ₄ NC可将聚糖信号强度显着增强几个数量级，并有效控制/减少/消除源内衰减（ISD）碎片。后者是通过调节 CNPs@Fe ₃ O ₄ NC 浓度来实现的，并允许同时研究完整和片段聚糖以及伪 MS ³分析。此外，CNPs@Fe ₃ O ₄ NCs还可以有效地用于直接在MALDI板上对样品进行脱盐，从而能够对来自模型糖蛋白和生物样品的未纯化的全甲基化聚糖进行直接MALDI-MS分析。板内脱盐通过减少样品损失来提高灵敏度。

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