Direct analysis of proteins and peptides in complex matrices is of significant importance for biological, medicinal and toxicological studies. Paper spray mass spectrometry is a promising method for the rapid determination of target compounds in various samples, but such a protocol is greatly limited by the hydrogen-bond and van der Waals interactions between the paper substrate and proteins and peptides. In this study, we reported the development of a robustly hydrophobic polystyrene-impregnated paper substrate with a surface energy of 49.0 mN m⁻¹ for paper spray in the analyses of proteins and peptides. The substrate was prepared by first coating polystyrene microspheres on the surface of filter paper followed by baking at 180 °C. We found that the baking temperature and coating amount of polystyrene had pronounced effects on the surface properties of the generated paper and the performance of paper spray in the analysis of target compounds. In addition, the capability of polystyrene-impregnated paper during paper spray was closely related to the composition of spray solvent. The developed paper has also been used for the measurement of various proteins and peptides (e.g., cytochrome c, lysozyme, myoglobin, angiotensin II and hemoglobin) in complex matrices (e.g., PBS and Tris buffer solutions and whole blood samples). The results demonstrated that in contrast to uncoated filter paper, the analysis sensitivity of paper spray using polystyrene-impregnated paper could be improved 12–1348-fold. This could ultimately make the PS-impregnated paper a potential substrate for paper spray in the direct analysis of proteins and peptides in various complex samples.

中文翻译：

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聚苯乙烯浸渍的纸质基材，用于直接质谱分析复杂基质中的蛋白质和肽†

直接分析复杂基质中的蛋白质和肽对于生物学，医学和毒理学研究具有重要意义。纸喷雾质谱法是一种快速测定各种样品中目标化合物的有前途的方法，但这种方法受到纸质底物与蛋白质和肽之间的氢键和范德华相互作用的极大限制。在这项研究中，我们报道了表面能为49.0 mN m ^-1的疏水性强的聚苯乙烯浸渍纸基材的开发。用于蛋白质和多肽分析中的纸张喷雾。通过首先在滤纸的表面上涂覆聚苯乙烯微球，然后在180°C下烘烤来制备基材。我们发现，在目标化合物的分析中，聚苯乙烯的烘烤温度和涂覆量对生成的纸张的表面性能和纸张喷雾的性能具有显着影响。另外，在纸喷雾过程中，聚苯乙烯浸渍纸的能力与喷雾溶剂的组成密切相关。发达纸也已用于各种蛋白质和肽（的测量例如，细胞色素c，溶菌酶，肌红蛋白，血管紧张素II和血红蛋白）的复杂的基质（例如，PBS和Tris缓冲溶液以及全血样本）。结果表明，与未涂布的滤纸相比，使用聚苯乙烯浸渍的纸喷雾的分析灵敏度可提高12–1348倍。最终，这可能会使PS浸渍纸成为直接喷雾分析各种复杂样品中蛋白质和肽的潜在基材。