Abstract: Objective The magnetic beads direct adsorption method system was established and applied to extracting and purifying and concentrating DNA template, and inspecting supernate DNA of the mixed stain samples, providing a reference method for forensic DNA testing. Methods Constant samples of inspecting unsuccessful with the Chelex-100 method were extracted and purified with the method of magnetic beads direct adsorption another time. In addition，we inspected supernate DNA of the mixed stain samples severally with the method of magnetic beads direct adsorption and Chelex-100. Then the samples were sequentially amplified with Identifiler-Plus kit, and the STR genotyping was detected by ABI 3500 Analyzer. Results The average detection rate of STR of the 94 DNA samples template of inspecting unsuccessful with the Chelex-100 method was 92.22% after being extracted and purified with the method of magnetic beads direct adsorption, and the average detection rate of STR of 20 supernate DNA of the mixed stain samples was 100% with the method of magnetic beads direct adsorption, but only was 94.06% detected with the Chelex-100 method. Conclusion The results suggest that the method of magnetic beads direct adsorption can apply to secondary extracting and purifying and concentrating DNA template, and inspecting supernate DNA of the mixed stain samples. The method is highly significant for forensic inspection practice.

Key words: forensic genetics, magnetic beads direct adsorption method, PCR amplification, extracting and purifying, mixed stain sample

摘要： 目的 建立磁珠直接吸附DNA快速检测体系，并对其在DNA模板的二次提取纯化、浓缩及混合斑上清液DNA检验中的应用进行探索。方法 采用磁珠直接吸附法，对分别两次采用Chelex-100法检验未能成功的常规生物检材DNA模板进行二次提取纯化、浓缩；另外同时采用磁珠直接吸附法和Chelex-100法对精液/阴道分泌液混合斑上清液进行DNA提取纯化，采用Identifiler-Plus试剂盒进行复合扩增后进行STR检测。结果 Chelex-100法检验失败的94份DNA模板，通过磁珠直接吸附法二次提取纯化后STR平均检出率为92.22 %；20份精液/阴道分泌液混合斑上清液的DNA检验中，Chelex-100法样本组STR平均检出率为94.06 %，磁珠直接吸附法样本组STR平均检出率为100 %。结论 磁珠直接吸附法可以应用于对DNA模板的二次提取纯化、浓缩及混合斑上清液DNA快捷检验中，对法医DNA检验具有较高的实际应用价值。

关键词: 法医遗传学, 磁珠直接吸附法, PCR扩增, 提取纯化, 混合斑