College of Science and Engineering, Flinders University, Australia.
College of Science and Engineering, Flinders University, Australia.
Forensic Sci Int Genet. 2018 Nov;37:95-101. doi: 10.1016/j.fsigen.2018.08.004. Epub 2018 Aug 8.
Touch DNA is one of the most common sample types submitted for DNA profiling. There is currently no process to visualise the presence of such DNA deposited when a person makes direct contact with items of forensic relevance. This report demonstrates the effective use of Diamond Dye to bind to DNA and allow visualisation of deposited cellular material using a mini-fluorescence microscope. Volunteers made contact with a range of items typical of those submitted as part of a forensic investigation. Contact was for less than 5 s and occurred either 15 min after hands were washed to remove any traces of DNA, and therefore under controlled conditions, or at an undefined time post handwashing to mimic real-world scenarios. Diamond Dye bound to cellular material on all the items used and in all cases it was clear where the volunteers had made this brief contact. It was also clear where no contact had been made. DNA profiling was performed on a sub-set of samples to confirm that the cellular material viewed under the microscope was human in origin and deposited by the person contacting the item; this was the result obtained in every sample tested. Diamond dye is relatively inexpensive, simple to apply, binds to the DNA in 3 s or less, has no mutagenic effects at the concentrations used, does not affect subsequent DNA profiling, and does not bind effectively to bacterial DNA. In combination with a mini-fluorescence microscope, this proof-of-concept study shows that otherwise invisible DNA deposited by touch can be visualised. The position and amount of cellular material deposited during even brief contact can be recorded allowing targeted sampling in any further DNA typing of forensically-significant items.
接触性 DNA 是提交进行 DNA 分析最常见的样本类型之一。目前，当一个人与法证相关物品直接接触时，还没有一种方法可以直观地看到这些 DNA 的存在。本报告展示了如何有效地使用钻石染料与 DNA 结合，并使用迷你荧光显微镜观察已沉积的细胞物质。志愿者接触了一系列通常作为法证调查一部分提交的物品。接触时间不到 5 秒，并且是在洗手去除任何 DNA 痕迹后 15 分钟进行的，因此是在受控条件下进行的，或者是在洗手后不定时进行的，以模拟现实场景。钻石染料与所有使用的物品上的细胞物质结合，在所有情况下，都能清楚地看到志愿者进行短暂接触的位置。也很清楚哪些地方没有接触。对一小部分样本进行了 DNA 分析，以确认在显微镜下观察到的细胞物质源自人类，并由接触物品的人沉积；这是对所有测试样本的结果。钻石染料相对便宜，使用简单，与 DNA 结合的时间不到 3 秒，在使用的浓度下没有诱变作用，不影响后续的 DNA 分析，也不能有效地与细菌 DNA 结合。结合迷你荧光显微镜，这项概念验证研究表明，否则无法看到的接触性 DNA 可以被直观地看到。即使是短暂接触时沉积的细胞物质的位置和数量也可以被记录下来，从而可以在对具有法证意义的物品进行任何进一步的 DNA 分型时进行有针对性的采样。
