Specific enrichment and efficient detection of phosphopeptides are important for phosphoproteomic analysis. Metal–organic frameworks (MOFs) have been proved to be effective enrichment materials combined with the analysis of mass spectrometry. In this work, we have developed a polycarboxylic group MOF-UiO-66-(COOH)₂ used as both efficient enrichment material for phosphopeptides and efficient desorption/ionization matrix of laser desorption/ionization time-of-flight mass spectrometry (LDI-TOF MS) without elution. The crystal is spherical and the particle size is about 200 nm. When using it as enrichment material and MS matrix, phosphopeptides of β-casein can be efficiently detected under superior low detection limits of 1 fmol μL⁻¹, and at an extremely low molar ratio of phosphoprotein/non-phosphoprotein (1:2000) mixtures, there are still four phosphopeptides that can be observed. When detecting real samples, most phosphopeptides of non-fat milk and human saliva can be observed, which is comparable with the literature.

Graphical abstract

磷酸肽的特异性富集和有效检测对于磷酸蛋白质组学分析很重要。金属有机框架（MOF）已被证明是结合质谱分析的有效富集材料。在这项工作中，我们开发了一种多元羧酸基团MOF-UiO-66-（COOH）₂，既用作磷酸肽的有效富集材料，又用作激光解吸/电离飞行时间质谱（LDI-TOF）的有效解吸/电离基质MS），无需洗脱。该晶体是球形的，并且粒径为约200nm。当将其用作富集材料和MS基质时，可以在1 fmolμL ^- 1的极低检测限下有效检测β-酪蛋白的磷酸肽，并且在磷蛋白/非磷蛋白混合物（1：2000）的摩尔比极低的情况下，仍然可以观察到四种磷肽。当检测真实样品时，可以观察到大多数脱脂牛奶和唾液中的磷酸肽，这与文献可比。

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