On the influence of various factors on the recovery efficiency and individual identification capability of exfoliated cells on chopsticks

In practical investigations, many biological samples containing exfoliated cells turn up at crime scenes, e.g., cigarette butts, glasses of water, clothing, chopsticks, etc. Improving the detection rate of exfoliated cells at crime scenes to obtain effective information is the focus of investigation work, but studies on chopsticks are relatively limited. This study investigated the influence of capture methods, chopstick textures, detergent treatment, exposure time and type of food on the recovery efficiency and individual identification capability of DNA from exfoliated cells of chopsticks. A cotton swab showed better DNA recovery efficiency than a flocked nylon swab and a exfoliated cells collector for four chopstick textures. The variation in DNA recovery efficiency shows a discrepancy between the different chopstick textures leading to bamboo > wood > plastic > stainless steel. After detergent treatment, relatively complete profiles (95.39–97.42 %) of the exfoliated cells DNA on bamboo and wooden chopsticks were still obtained. The recovery efficiency and persistence of DNA on bamboo and wooden chopsticks are higher and less affected by external factors. The effect of food types on the exfoliated cells on chopsticks showed that the quality of DNA profiles obtained after eating noodles and rice compared to hot pot can be used for downstream individual identification. This work has shown that the different porosity of chopstick textures leads to a different ability of chopsticks to absorb DNA. The exfoliated cells on bamboo and wooden chopsticks after treatment with detergents, a 30-day exposure or the consumption of noodles and rice are also a valuable tool to identify the perpetrator and/or the victim. These results could be useful in police investigations and in court to assess the chances of successful DNA genotyping and to facilitate decisions on the usability of DNA recovered from crime scenes.