College of Science and Engineering, Flinders University, GPO Box 2100, Adelaide, 5001, South Australia, Australia.
Forensic Science SA, GPO Box 2790, Adelaide, 5001, South Australia, Australia.
Anal Bioanal Chem. 2018 Sep;410(24):6165-6175. doi: 10.1007/s00216-018-1223-3. Epub 2018 Jul 12.
Violent contact between individuals during a crime can result in body fluids becoming trapped under the fingernails of the individuals involved. The traces under fingernails represent valuable forensic evidence because DNA profiling can indicate from whom the trace originated and proteomic methods can be used to determine the type of fluid in the trace, thus providing evidence as to the circumstances surrounding the crime. Here, we present an initial study of an analytical strategy that involves two complementary techniques, direct PCR DNA profiling and direct mass spectrometry-based protein biomarker detection, for the comprehensive examination of traces of biological fluids gathered from underneath fingernails. With regard to protein biomarker detection, direct MALDI-ToF MS/MS is very sensitive, allowing results to be obtained from biological material present on only a few fibres plucked from a microswab used to collect the traces. Human cornulin, a protein biomarker for vaginal fluid, could be detected up to 5 h after it had been deposited under fingernails whereas haemoglobin, a biomarker for blood, is somewhat more persistent under fingernails and could be detected up to 18 h post-deposition. Bottom-up tandem mass spectrometry techniques were used to provide a high level of confidence in assigning the identity of protein biomarkers. nLC-ESI-qToF MS/MS offered higher levels of confidence and the ability to detect traces that had been present under fingernails for longer periods of time, but this performance came with the cost of longer analysis time and a more laborious sampling approach. Graphical abstract ᅟ.
犯罪过程中个体之间的暴力接触会导致体液被困在涉案人员的指甲下。指甲下的痕迹是有价值的法医证据，因为 DNA 分析可以表明痕迹来自谁，蛋白质组学方法可用于确定痕迹中液体的类型，从而为犯罪发生时的情况提供证据。在这里，我们提出了一种分析策略的初步研究，该策略涉及两种互补技术，即直接 PCR DNA 分析和基于直接 MALDI-TOF MS/MS 的蛋白质生物标志物检测，用于全面检查从指甲下收集的生物体液痕迹。关于蛋白质生物标志物检测，直接 MALDI-TOF MS/MS 非常灵敏，允许从仅从用于收集痕迹的微拭子上采集的几根纤维中存在的生物材料中获得结果。人角蛋白是阴道液的蛋白质生物标志物，在沉积在指甲下后 5 小时内即可检测到，而血红蛋白是血液的生物标志物，在指甲下的持久性稍高，在沉积后 18 小时内仍可检测到。自上而下的串联质谱技术用于提供高度置信度，以确定蛋白质生物标志物的身份。nLC-ESI-qToF MS/MS 提供了更高的置信度和检测指甲下存在更长时间痕迹的能力，但这种性能伴随着分析时间更长和采样方法更繁琐的代价。
