Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21231, United States.
Anal Chem. 2012 Sep 18;84(18):7626-32. doi: 10.1021/ac301423f. Epub 2012 Aug 28.
Matrix-assisted laser desorption/ionization (MALDI) has proven an effective tool for fast and accurate determination of many molecules. However, the detector sensitivity and chemical noise compromise the detection of many invaluable low-abundance molecules from biological and clinical samples. To challenge this limitation, we developed a targeted analyte detection (TAD) technique. In TAD, the target analyte is selectively elevated by spiking a known amount of that analyte into the sample, thereby raising its concentration above the noise level, where we take advantage of the improved sensitivity to detect the presence of the endogenous analyte in the sample. We assessed TAD on three peptides in simple and complex background solutions with various exogenous analyte concentrations in two MALDI matrices. TAD successfully improved the limit of detection (LOD) of target analytes when the target peptides were added to the sample in a concentration close to optimum concentration. The optimum exogenous concentration was estimated through a quantitative method to be approximately equal to the original LOD for each target. Also, we showed that TAD could achieve LOD improvements on an average of 3-fold in a simple and 2-fold in a complex sample. TAD provides a straightforward assay to improve the LOD of generic target analytes without the need for costly hardware modifications.
基质辅助激光解吸/电离（MALDI）已被证明是一种快速、准确测定多种分子的有效工具。然而，检测器的灵敏度和化学噪声限制了从生物和临床样本中检测许多有价值的低丰度分子。为了应对这一限制，我们开发了一种靶向分析物检测（TAD）技术。在 TAD 中，通过向样品中加入已知量的目标分析物来选择性地提高目标分析物的浓度，从而使其浓度高于噪声水平，从而利用提高的灵敏度来检测样品中内源性分析物的存在。我们在两种 MALDI 基质中，用三种简单和复杂背景溶液中的肽，评估了具有不同外源性分析物浓度的 TAD。当目标肽以接近最佳浓度添加到样品中时，TAD 成功地提高了目标分析物的检测限（LOD）。通过定量方法估计最佳外源性浓度约等于每个目标的原始 LOD。此外，我们还表明，TAD 可以使简单样品的 LOD 提高平均 3 倍，复杂样品的 LOD 提高 2 倍。TAD 提供了一种简单的测定方法，可在不改变昂贵硬件的情况下提高通用目标分析物的 LOD。
