Comparison of Isohelix™ and Rayon swabbing systems for touch DNA recovery from metal surfaces

Dan O. M. Bonsu, Matthew Rodie, Denice Higgins, Julianne Henry, Jeremy J. Austin

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


A previous study evaluating two swabbing systems found that DNA was best recovered from sterile metal substrates using an Isohelix™ swab wetted with isopropyl alcohol rather than a Rayon swab with water as the wetting agent. We tested the same swabbing systems on metal (aluminum, brass, and stainless steel) and plastic substrates in a regularly touched environment to simulate the non-deliberate transfer of touch evidence likely seen in a casework scenario, to ascertain the performance of these swabs in an uncontrolled situation. Higher amounts of touch DNA were recovered with Isohelix™ swabs (0.5 – 3.3 ng) compared to Rayon swabs (0.13 – 1.2 ng). The Isohelix™ swabbing system was found to significantly recover more touch DNA (p = 0.04) from the metal substrates than the Rayon swabbing system, consistent with the findings of our previous work. The results contribute to our understanding of the impact of sample collection techniques on touch DNA recovery from problematic metal surfaces and suggest that supplemental cleaning of substrates as a precautionary step against the spread of infections may affect touch DNA persistence and the recovery efficiency of swabs.

Original languageEnglish
Pages (from-to)577-584
Number of pages8
JournalForensic Science, Medicine, and Pathology
Issue number4
Early online date21 Oct 2021
Publication statusPublished - Dec 2021


  • DNA recovery
  • Forensic Science
  • Isohelix™ swab
  • Metals
  • Rayon swab
  • Short tandem repeat (STR)
  • Touch DNA


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