Mass spectrometry analysis coupled with stable isotope labeling is a powerful strategy for comparative analysis of N-glycans for glycan biomarker discovery. Here, a novel method combining dual isotopic labeling and fluorous solid-phase extraction was developed, enabling selective enrichment, simultaneous quantitation and recognition of neutral/sialylated glycans from serum samples by mass spectrometry. The isotopic label of fluorous compound on the reducing end of glycans acts as an enrichment tag and provides mass difference between neutral glycans from different samples, while the isotopic label on the non-reducing end of glycans protects the sialic acid residue and provides additional mass difference for sialylated glycans. Therefore, the neutral/sialylated glycans could be simultaneously enriched through the fluorous solid-phase extraction (FSPE) and quantified by mass spectrometry. This method provided a good linearity (R2 > 0.99) and high reproducibility (CV < 20%) within 2 orders of magnitude in the dynamic range. Finally, this strategy was successfully applied to investigate the N-glycome alteration in serum associated with gastric cancer (GC). Bisecting GlcNAc and triantennary glycan compositions were found to be significantly changed between GC cases (n = 50) and healthy control, indicating the great potential to be novel biomarkers for GC early diagnosis.

中文翻译：

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双同位素标记结合氟固相萃取同时发现作为胃癌生物标志物的中性/唾液酸化 N-聚糖

质谱分析与稳定同位素标记相结合是对 N-聚糖进行比较分析以发现聚糖生物标志物的强大策略。在这里，开发了一种结合双同位素标记和氟固相萃取的新方法，能够通过质谱法选择性富集、同时定量和识别血清样品中的中性/唾液酸化聚糖。聚糖还原端的氟化合物同位素标记作为富集标签，提供不同样品中性聚糖之间的质量差异，而聚糖非还原端的同位素标记保护唾液酸残基并提供额外的质量差异对于唾液酸化聚糖。所以，中性/唾液酸化聚糖可以同时通过含氟固相萃取 (FSPE) 富集并通过质谱法定量。该方法在动态范围内提供了 2 个数量级的良好线性 (R2 > 0.99) 和高重现性 (CV < 20%)。最后，该策略成功应用于研究与胃癌 (GC) 相关的血清中 N-糖组的变化。发现二等分 GlcNAc 和三触角聚糖组成在 GC 病例（n = 50）和健康对照之间发生显着变化，表明作为 GC 早期诊断的新型生物标志物的巨大潜力。该策略已成功应用于研究与胃癌 (GC) 相关的血清中的 N-糖组变化。发现二等分的 GlcNAc 和三触角聚糖组成在 GC 病例（n = 50）和健康对照之间发生显着变化，表明作为 GC 早期诊断的新型生物标志物的巨大潜力。该策略已成功应用于研究与胃癌 (GC) 相关的血清中的 N-糖组变化。发现二等分 GlcNAc 和三触角聚糖组成在 GC 病例（n = 50）和健康对照之间发生显着变化，表明作为 GC 早期诊断的新型生物标志物的巨大潜力。