Forensic sciences are an accumulation of a large variety of disciplines. One of such focuses on crime scenes and trace collection through police investigators. If any are present, they need to be collected and sent to external laboratories for DNA profiling. The collection of evidence is one of the first steps in line during the investigations and mostly done through swabbing [1-3] and in specific circumstances by tape-lifting [4]. Logically better sampling translates to all downstream analysis and increases the chances of generating a full DNA profile, hence the importance of maximizing the sampling efficiency.
In the past a lot of effort has been undertaken to compare different swab types, materials and substrate dependences on the DNA recovery [3-5]. Nonetheless in total these investigations mostly considered the final DNA concentration and lack and understanding of the individual steps of the sampling process.
The swab based sampling can be split into three individual steps, which possess different characteristics and physical principles.
1. Collection
2. Drying
3. Release
Based on these, the overall sampling efficiency can be defined as the transfer from the original substrate to the analysis device.
The goal is to improve the release mechanism of cellular materials off cotton swabs and other surfaces through switchable polymer coatings.
Assignment
The project requires the application of polymer coatings onto different substrates and cell culturing. After successful fabrication of these alternative collection tools, the switching dynamics, surface affinities, topography and release efficiency need to be studied through various techniques, like contact angle measurement, fluorescent microscopy, scanning electron microscopy etc.
References
1. Bruijns, B. What Are the Limitations and Challenges of Swab-Based DNA Sampling? Forensic Sciences, 2024. 4, 76-95 DOI: 10.3390/forensicsci4010006.
2. Bonsu, D.O.M., et al., Evaluation of the efficiency of Isohelix™ and Rayon swabs for recovery of DNA from metal surfaces. Forensic Science, Medicine and Pathology, 2021. 17(2): p. 199-207.
3. Abdullah, A., B. Szkuta, and G.E. Meakin, Effect of swabbing technique and duration on forensic DNA recovery. Science & Justice, 2023. 63(3): p. 343-348.
4. Plaza, D.T., et al., Nondestructive Biological Evidence Collection with Alternative Swabs and Adhesive Lifters. Journal of Forensic Sciences, 2016. 61(2): p. 485-488.
5. Bruijns, B.B., R.M. Tiggelaar, and H. Gardeniers, The Extraction and Recovery Efficiency of Pure DNA for Different Types of Swabs. Journal of Forensic Sciences, 2018. 63(5): p. 1492-1499.
Contact information
Michel Nunnenkamp; E-mail: m.nunnenkamp-1@utwente.nl