A novel sensing chip was designed for MALDI-MS quantitation of acid phosphatase (ACP). The ACP sensing chip was constructed through non-covalent interaction of streptavidin and biotin for the assembly of biotinylated peptide substrate on biotinylated polyethylene-glycol (PEG) modified indium-tin oxide (ITO) slide. In the presence of ACP, the peptide substrate was dephosphorylated under acidic condition to generate a new mass signal. The quantitative assay of ACP was achieved with the mass signal ratio of product to the sum of product and left peptide substrate. Under optimal detection conditions, the ratio was linearly correlated with the concentration of ACP in the range of 0.05–12 g/L with a detection limit (LOD) of 0.04 g/L. The designed ACP sensing chip has been used to analyze ACP in complex clinical samples, which exhibited high selectivity, good repeatability, and admirably anti-interference ability. This work further demonstrates the concept of MS sensing and the application of MALDI-MS in quantitative analysis, and provides a convenient method for the quantitation of proteases in clinical diagnosis.

设计了一种新型传感芯片，用于MALDI-MS定量分析酸性磷酸酶（ACP）。通过链霉亲和素和生物素的非共价相互作用构建ACP传感芯片，以在生物素化的聚乙二醇（PEG）修饰的铟锡氧化物（ITO）载玻片上组装生物素化的肽底物。在ACP存在下，肽底物在酸性条件下被去磷酸化以产生新的质量信号。ACP的定量测定是通过产物与产物和残留肽底物总和的质量信号比实现的。在最佳检测条件下，该比率与ACP浓度在0.05–12 g / L范围内线性相关，检测极限（LOD）为0.04 g / L。设计的ACP传感芯片已用于分析具有高选择性的复杂临床样品中的ACP，良好的重复性，以及出色的抗干扰能力。这项工作进一步证明了MS感测的概念以及MALDI-MS在定量分析中的应用，并为临床诊断中的蛋白酶定量提供了便利的方法。