Department of Biomedical Engineering, Tsinghua University School of Medicine , Beijing 100084, China.
Beijing Engineering Research Center of Crime Scene Evidence Examination, Institute of Forensic Science , Beijing 100038, China.
Biomicrofluidics. 2015 Aug 31;9(4):044127. doi: 10.1063/1.4928453. eCollection 2015 Jul.
In sexual assault cases, forensic samples are a mixture of sperm from the perpetrator and epithelial cells from the victim. To obtain an independent short tandem repeat (STR) profile of the perpetrator, sperm cells must be separated from the mixture of cells. However, the current method used in crime laboratories, namely, differential extraction, is a time-consuming and labor-intensive process. To achieve a rapid and automated sample pretreatment process, we fabricated a microdevice for hydrodynamic and size-based separation of sperm and epithelial cells. When cells in suspension were introduced into the device's microfluidic channels, they were forced to flow along different streamlines and into different outlets due to their different diameters. With the proposed microdevice, sperm can be separated within a short period of time (0.5 h for a 50-μl mock sample). The STR profiles of the products in the sperm outlet reservoir demonstrated that a highly purified male DNA fraction could be obtained (94.0% male fraction). This microdevice is of low-cost and can be easily integrated with other subsequent analysis units, providing great potential in the process of analyzing sexual assault evidence as well as in other areas requiring cell sorting.
在性侵犯案件中，法医样本是犯罪者精子和受害者上皮细胞的混合物。为了获得犯罪者独立的短串联重复序列（STR）图谱，必须将精子细胞从细胞混合物中分离出来。然而，犯罪实验室目前使用的方法，即差异提取，是一个耗时且劳动密集型的过程。为了实现快速和自动化的样品预处理过程，我们制造了一种用于基于流体动力和大小的精子和上皮细胞分离的微器件。当悬浮细胞被引入设备的微流道中时，由于它们的不同直径，它们被迫沿着不同的流线并进入不同的出口流动。使用所提出的微器件，可以在短时间内（50 μl 模拟样品的 0.5 h）分离精子。精子出口储液器中的产物 STR 图谱表明，可以获得高度纯化的男性 DNA 部分（94.0%的男性部分）。这种微器件成本低，并且可以很容易地与其他后续分析单元集成，在分析性侵犯证据以及其他需要细胞分选的领域具有很大的潜力。
