Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore.
Anal Chem. 2012 Aug 7;84(15):6693-700. doi: 10.1021/ac301119r. Epub 2012 Jul 26.
Phosphopeptides play a crucial role in many biological processes and constitute some of the most powerful biomarkers in disease detection. However they are often present in very low concentration, which makes their detection highly challenging. Here, we demonstrate the use of a solution-dispersible graphene-titania platform for the selective extraction of phosphopeptides from peptide mixtures. This is followed by direct analysis by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS). The efficient charge and energy exchange between graphene and TiO(2) during laser irradiation in SELDI-TOF MS promotes the soft ionization of analytes and affords a detection limit in the attomole range, which is 10(2)-10(5) more sensitive than conventional platforms. The graphene-titania platform can also be used for detecting phosphopeptides in cancer cells (HeLa cells), where it shows high specificity (94%). An expanded library of 967 unique phosphopeptides is detected using significantly reduced loading of extraction matrixes compared to conventional TiO(2) bead-based assays.
磷酸肽在许多生物过程中起着至关重要的作用，并且构成了一些最强大的疾病检测生物标志物。然而，它们通常存在于非常低的浓度，这使得它们的检测极具挑战性。在这里，我们展示了一种可溶液分散的石墨烯-二氧化钛平台，用于从肽混合物中选择性提取磷酸肽。然后通过表面增强激光解吸/电离飞行时间质谱（SELDI-TOF MS）直接分析。在 SELDI-TOF MS 中激光辐照期间，石墨烯和 TiO2 之间的有效电荷和能量交换促进了分析物的软电离，并提供了飞秒级的检测限，比传统平台灵敏 10^2-10^5 倍。石墨烯-二氧化钛平台还可用于检测癌细胞（HeLa 细胞）中的磷酸肽，其特异性高达 94%。与传统的 TiO2 珠基测定相比，使用显著减少的提取基质负载，可以检测到 967 种独特磷酸肽的扩展文库。
