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Recipon M, Agniel R, Kunemann P, Ponche A, Carreiras F, Hermitte F, Leroy-Dudal J, Hubac S, Gallet O, Kellouche S. Detection of invisible biological traces in relation to the physicochemical properties of substrates surfaces in forensic casework. Sci Rep 2024; 14:13271. [PMID: 38858407 PMCID: PMC11164948 DOI: 10.1038/s41598-024-63911-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Accepted: 06/03/2024] [Indexed: 06/12/2024] Open
Abstract
Touch DNA, which can be found at crime scenes, consists of invisible biological traces deposited through a person's skin's contact with an object or another person. Many factors influence touch DNA transfer, including the "destination" substrate's surface. The latter's physicochemical characteristics (wettability, roughness, surface energy, etc.) will impact touch DNA deposition and persistence on a substrate. We selected a representative panel of substrates from objects found at crime scenes (glass, polystyrene, tiles, raw wood, etc.) to investigate the impact of these characteristics on touch DNA deposition and detection. These were shown to impact cell deposition, morphology, retention, and subsequent touch DNA genetic analysis. Interestingly, cell-derived fragments found within keratinocyte cells and fingermarks using in vitro touch DNA models could be successfully detected whichever the substrates' physicochemistry by targeting cellular proteins and carbohydrates for two months, indoors and outdoors. However, swabbing and genetic analyses of such mock traces from different substrates produced informative profiles mainly for substrates with the highest surface free energy and therefore the most hydrophilic. The substrates' intrinsic characteristics need to be considered to better understand both the transfer and persistence of biological traces, as well as their detection and collection, which require an appropriate methodology and sampling device to get informative genetic profiles.
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Affiliation(s)
- Mathilde Recipon
- Equipe de Recherche sur les Relations Matrice Extracellulaire-Cellules, ERRMECe, (EA1391), Groupe Matrice Extracellulaire et Physiopathologie (MECuP), Institut des Matériaux, I-MAT (FD4122), CY Cergy Paris Université, Neuville Sur Oise, France.
- Institut de Recherche Criminelle de La Gendarmerie Nationale, Cergy-Pontoise, France.
| | - Rémy Agniel
- Equipe de Recherche sur les Relations Matrice Extracellulaire-Cellules, ERRMECe, (EA1391), Groupe Matrice Extracellulaire et Physiopathologie (MECuP), Institut des Matériaux, I-MAT (FD4122), CY Cergy Paris Université, Neuville Sur Oise, France
| | | | - Arnaud Ponche
- Institut de Science Des Matériaux de Mulhouse, Mulhouse, France
| | - Franck Carreiras
- Equipe de Recherche sur les Relations Matrice Extracellulaire-Cellules, ERRMECe, (EA1391), Groupe Matrice Extracellulaire et Physiopathologie (MECuP), Institut des Matériaux, I-MAT (FD4122), CY Cergy Paris Université, Neuville Sur Oise, France
| | - Francis Hermitte
- Institut de Recherche Criminelle de La Gendarmerie Nationale, Cergy-Pontoise, France
| | - Johanne Leroy-Dudal
- Equipe de Recherche sur les Relations Matrice Extracellulaire-Cellules, ERRMECe, (EA1391), Groupe Matrice Extracellulaire et Physiopathologie (MECuP), Institut des Matériaux, I-MAT (FD4122), CY Cergy Paris Université, Neuville Sur Oise, France
| | - Sylvain Hubac
- Institut de Recherche Criminelle de La Gendarmerie Nationale, Cergy-Pontoise, France
| | - Olivier Gallet
- Equipe de Recherche sur les Relations Matrice Extracellulaire-Cellules, ERRMECe, (EA1391), Groupe Matrice Extracellulaire et Physiopathologie (MECuP), Institut des Matériaux, I-MAT (FD4122), CY Cergy Paris Université, Neuville Sur Oise, France
| | - Sabrina Kellouche
- Equipe de Recherche sur les Relations Matrice Extracellulaire-Cellules, ERRMECe, (EA1391), Groupe Matrice Extracellulaire et Physiopathologie (MECuP), Institut des Matériaux, I-MAT (FD4122), CY Cergy Paris Université, Neuville Sur Oise, France.
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2
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Madden I, Taylor D, Mitchell N, Goray M, Henry J. Predicting probative levels of touch DNA on tapelifts using Diamond™ Nucleic Acid Dye. Forensic Sci Int Genet 2024; 70:103024. [PMID: 38335775 DOI: 10.1016/j.fsigen.2024.103024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 01/29/2024] [Accepted: 02/02/2024] [Indexed: 02/12/2024]
Abstract
Tapelifting is a common strategy to recover touch DNA deposits from porous exhibits in forensic DNA casework. However, it is known that only about 30 % of tapelifts submitted for DNA analysis in operational forensic laboratories yield profiles suitable for comparison or upload to a searchable database. A reliable means to identify and remove non-probative tapelifts from the workflow would reduce sample backlogs and provide significant cost savings. We investigated whether the amount of macroscopic or microscopic fluorescence on a tapelift following staining with Diamond Nucleic Acid Dye (DD), determined using a Polilight and Dino Lite microscope respectively, could predict the DNA yield and/or the DNA profiling outcome using controlled (saliva), semi-controlled (finger mark) and uncontrolled (clothing) samples. Both macroscopic and microscopic DD fluorescence could predict DNA yield and profiling outcome for all sample types, however the predictive power deteriorated as the samples became less controlled. For tapelifts of clothing, which are operationally relevant, Polilight fluorescence scores were significantly impacted by clothing fibres and other non-cellular debris and could not be used to identify non-probative samples. The presence of less than 500 cells on a clothing tapelift using microscopic counting of stained corneocytes was identified as a potential threshold for a non-probative DNA profiling outcome. A broader examination of the reliability of this threshold using a casework trial is recommended. Due to the labour intensiveness of microscopic cell counting, and the increased risk of inadvertent contamination, automation of this process using image software in conjunction with artificial neural networks (ANN) should be explored.
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Affiliation(s)
- Isla Madden
- College of Science and Engineering, Flinders University of South Australia, Bedford Park, South Australia 5042, Australia
| | - Duncan Taylor
- College of Science and Engineering, Flinders University of South Australia, Bedford Park, South Australia 5042, Australia; Forensic Science SA, GPO Box 2790, Adelaide, South Australia 5001, Australia
| | - Natasha Mitchell
- Forensic Science SA, GPO Box 2790, Adelaide, South Australia 5001, Australia
| | - Mariya Goray
- College of Science and Engineering, Flinders University of South Australia, Bedford Park, South Australia 5042, Australia
| | - Julianne Henry
- College of Science and Engineering, Flinders University of South Australia, Bedford Park, South Australia 5042, Australia; Forensic Science SA, GPO Box 2790, Adelaide, South Australia 5001, Australia.
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3
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Nolan M, Linacre A. Cell counting to monitor swab efficiency. J Forensic Sci 2024; 69:1002-1010. [PMID: 38380584 DOI: 10.1111/1556-4029.15495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 02/08/2024] [Accepted: 02/12/2024] [Indexed: 02/22/2024]
Abstract
Plastic bags, such as ziplock bags, have been used to transport illicit materials worldwide; however, very few studies have tried to optimize the recovery of DNA from these items. This study reports on the best combination of swabs and moistening solution for the greatest recovery of cellular material from ziplock bags. Five swabs, two different variations of Copan Diagnostics nylon 4N6FLOQSwabs, one Medical Wire rayon DRYSWAB, one IsoHelix rayon swab, and one Livingstone cotton swab, were evaluated with two moistening solutions, Triton X-100 in either distilled water or isopropanol. Fingermarks were deposited on ziplock bags and stained with Diamond™ Nucleic Acid Dye to allow visualization of the cells pre- and post-swabbing to determine the number of cells recovered. Based on cell counting data, swabs moistened with Triton X-100 in distilled water performed better than those moistened with isopropanol. Livingstone cotton swabs had the worst recovery of cellular material, while the other swabs tested had no significant difference in their respective solutions. A comparison of the best three swabs for cellular recovery yielded no differences in the DNA concentration extracted. A linear relationship was observed between the log number of cells recovered by swabbing and the DNA concentration following extraction and quantification. The process of monitoring cell collection using fluorescence microscopy on ziplock bags allowed evaluation of swabbing efficacy. Additionally, this study highlights the ability to evaluate cellular recovery independently of traditional extraction, quantification, or profiling techniques which may unequally affect samples.
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Affiliation(s)
- Madison Nolan
- College of Science and Engineering, Flinders University, Adelaide, South Australia, Australia
| | - Adrian Linacre
- College of Science and Engineering, Flinders University, Adelaide, South Australia, Australia
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4
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Goray M, Taylor D, Bibbo E, Fantinato C, Fonneløp AE, Gill P, van Oorschot RAH. Emerging use of air eDNA and its application to forensic investigations - A review. Electrophoresis 2024; 45:916-932. [PMID: 38419135 DOI: 10.1002/elps.202300228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 12/17/2023] [Accepted: 02/19/2024] [Indexed: 03/02/2024]
Abstract
Biological material is routinely collected at crime scenes and from exhibits and is a key type of evidence during criminal investigations. Improvements in DNA technologies allow collection and profiling of trace samples, comprised of few cells, significantly expanding the types of exhibits targeted for DNA analysis to include touched surfaces. However, success rates from trace and touch DNA samples tend to be poorer compared to other biological materials such as blood. Simultaneously, there have been recent advances in the utility of environmental DNA collection (eDNA) in identification and tracking of different biological organisms and species from bacteria to naked mole rats in different environments, including, soil, ice, snow, air and aquatic. This paper examines the emerging methods and research into eDNA collection, with a special emphasis on the potential forensic applications of human DNA collection from air including challenges and further studies required to progress implementation.
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Affiliation(s)
- Mariya Goray
- College of Science and Engineering, Flinders University, Adelaide, South Australia, Australia
| | - Duncan Taylor
- College of Science and Engineering, Flinders University, Adelaide, South Australia, Australia
- Forensic Science SA, Adelaide, South Australia, Australia
| | - Emily Bibbo
- College of Science and Engineering, Flinders University, Adelaide, South Australia, Australia
| | - Chiara Fantinato
- Forensic Genetics Research Group, Department of Forensic Sciences, Oslo University Hospital, Oslo, Norway
- Department of Forensic Medicine, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Ane Elida Fonneløp
- Forensic Genetics Research Group, Department of Forensic Sciences, Oslo University Hospital, Oslo, Norway
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway
| | - Peter Gill
- Forensic Genetics Research Group, Department of Forensic Sciences, Oslo University Hospital, Oslo, Norway
- Department of Forensic Medicine, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Roland A H van Oorschot
- Victoria Police Forensic Services Department, Office of Chief Forensic Scientist, Macleod, Victoria, Australia
- School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, Victoria, Australia
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5
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Goray M, Taylor D, Bibbo E, Patel D, Fantinato C, Fonneløp AE, Gill P, van Oorschot RAH. Up in the air: Presence and collection of DNA from air and air conditioner units. Electrophoresis 2024; 45:933-947. [PMID: 38416600 DOI: 10.1002/elps.202300227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 01/23/2024] [Accepted: 02/19/2024] [Indexed: 03/01/2024]
Abstract
Biological material is routinely collected at crime scenes and from exhibits and is a key type of evidence during criminal investigations. Touch or trace DNA samples from surfaces and objects deemed to have been contacted are frequently collected. However, a person of interest may not leave any traces on contacted surfaces, for example, if wearing gloves. A novel means of sampling human DNA from air offers additional avenues for DNA collection. In the present study, we report on the results of a pilot study into the prevalence and persistence of human DNA in the air. The first aspect of the pilot study investigates air conditioner units that circulate air around a room, by sampling units located in four offices and four houses at different time frames post-cleaning. The second aspect investigates the ability to collect human DNA from the air in rooms, with and without people, for different periods of time and with different types of collection filters. Results of this pilot study show that human DNA can be collected on air conditioner unit surfaces and from the air, with air samples representing the more recent occupation while air conditioner units showing historic use of the room.
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Affiliation(s)
- Mariya Goray
- College of Science and Engineering, Flinders University, Adelaide, South Australia, Australia
| | - Duncan Taylor
- College of Science and Engineering, Flinders University, Adelaide, South Australia, Australia
- Forensic Science SA, Adelaide, South Australia, Australia
| | - Emily Bibbo
- College of Science and Engineering, Flinders University, Adelaide, South Australia, Australia
| | - Dhruvi Patel
- College of Science and Engineering, Flinders University, Adelaide, South Australia, Australia
| | - Chiara Fantinato
- Forensic Genetics Research Group, Department of Forensic Sciences, Oslo University Hospital, Oslo, Norway
- Department of Forensic Medicine, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Ane Elida Fonneløp
- Forensic Genetics Research Group, Department of Forensic Sciences, Oslo University Hospital, Oslo, Norway
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway
| | - Peter Gill
- Forensic Genetics Research Group, Department of Forensic Sciences, Oslo University Hospital, Oslo, Norway
- Department of Forensic Medicine, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Roland A H van Oorschot
- Victoria Police Forensic Services Department, Office of Chief Forensic Scientist, Macleod, Victoria, Australia
- School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, Victoria, Australia
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6
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McDonald C, Taylor D, Linacre A. PCR in Forensic Science: A Critical Review. Genes (Basel) 2024; 15:438. [PMID: 38674373 PMCID: PMC11049589 DOI: 10.3390/genes15040438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Revised: 03/26/2024] [Accepted: 03/27/2024] [Indexed: 04/28/2024] Open
Abstract
The polymerase chain reaction (PCR) has played a fundamental role in our understanding of the world, and has applications across a broad range of disciplines. The introduction of PCR into forensic science marked the beginning of a new era of DNA profiling. This era has pushed PCR to its limits and allowed genetic data to be generated from trace DNA. Trace samples contain very small amounts of degraded DNA associated with inhibitory compounds and ions. Despite significant development in the PCR process since it was first introduced, the challenges of profiling inhibited and degraded samples remain. This review examines the evolution of the PCR from its inception in the 1980s, through to its current application in forensic science. The driving factors behind PCR evolution for DNA profiling are discussed along with a critical comparison of cycling conditions used in commercial PCR kits. Newer PCR methods that are currently used in forensic practice and beyond are examined, and possible future directions of PCR for DNA profiling are evaluated.
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Affiliation(s)
- Caitlin McDonald
- College of Science & Engineering, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia; (C.M.); (A.L.)
| | - Duncan Taylor
- College of Science & Engineering, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia; (C.M.); (A.L.)
- Forensic Science SA, GPO Box 2790, Adelaide, SA 5001, Australia
| | - Adrian Linacre
- College of Science & Engineering, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia; (C.M.); (A.L.)
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Nolan M, Handt O, Linacre A. Persistence of cellular material after exposure to water. J Forensic Sci 2023; 68:2128-2137. [PMID: 37356058 DOI: 10.1111/1556-4029.15316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 06/08/2023] [Accepted: 06/12/2023] [Indexed: 06/27/2023]
Abstract
Disposing of items of forensic relevance in bodies of water is one countermeasure offenders can use to avoid detection. The impact of immersion in water has been explored for blood, saliva, and semen; however, few studies have assessed touch DNA. Here we report on the effect of exposure to water on the persistence of touch DNA over prolonged periods of time. To evaluate the persistence of cells from touch DNA, after water exposure, three substrates and two water types were tested: plastic, metal, and ceramic, submerged into seawater or tap water. Diamond™ Nucleic Acid Dye was used to stain cells deposited by touch. Cell counts before and after water exposure were compared to investigate cell loss over time, ranging from 6 hours to 5 days. A logarithmic increase in the percent of cells lost was observed over time when the data for substrate and water type conditions were combined. Substrate type influenced the persistence of cells, with the metal substrate retaining cells longer than plastic or ceramic. The influence of water type appeared dependent on the substrate, with varied cell persistence on metal whereas plastic and ceramic recorded similar cell loss over time between water types. The ability to visualize cells after exposure to water could assist in triaging evidence within operational forensic laboratories and allow for targeted sampling. This proof-of-concept study demonstrated that greater than 50% of cells can persist on various items submerged in aqueous environments for at least 5 days, highlighting the possibility for downstream DNA testing.
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Affiliation(s)
- Madison Nolan
- College of Science and Engineering, Flinders University, Adelaide, Australia
| | - Oliva Handt
- College of Science and Engineering, Flinders University, Adelaide, Australia
- Forensic Science South Australia, Adelaide, Australia
| | - Adrian Linacre
- College of Science and Engineering, Flinders University, Adelaide, Australia
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8
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Petcharoen P, Kirkbride KP, Linacre A. Monitoring cell loss through repetitive deposition. J Forensic Sci 2022; 67:2453-2457. [DOI: 10.1111/1556-4029.15140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 09/05/2022] [Accepted: 09/08/2022] [Indexed: 11/28/2022]
Affiliation(s)
- Piyamas Petcharoen
- School of Biology, Institute of Science Suranaree University of Technology Nakhon Ratchasima Thailand
- College of Science & Engineering Flinders University Adelaide South Australia Australia
| | | | - Adrian Linacre
- College of Science & Engineering Flinders University Adelaide South Australia Australia
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Panjaruang P, Romgaew T, Aobaom S. Detection of touch DNA evidence on swab by SYBR®Green I Nucleic Acid Gel Stain. Forensic Sci Int 2022; 341:111477. [DOI: 10.1016/j.forsciint.2022.111477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Accepted: 09/25/2022] [Indexed: 11/15/2022]
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10
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Martin B, Kaesler T, Kirkbride KP, Linacre A. The influences of dusty environments on the STR typing success of post-detonation touch DNA samples. Forensic Sci Int Genet 2021; 57:102651. [PMID: 34896974 DOI: 10.1016/j.fsigen.2021.102651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 12/02/2021] [Accepted: 12/03/2021] [Indexed: 11/04/2022]
Abstract
As the use of improvised explosive devices (IEDs) in a broad spectrum of offences continues, it is vital that research is performed to assess the capabilities of the forensic DNA profiling technology currently available to provide information as to potential perpetrators. This work investigates some of the most important gaps in our understanding surrounding the poor success rates in DNA profiling obtained through the sampling of touch DNA on post-detonation IED samples. It has been previously suggested that the use of Diamond™ Nucleic Acid Dye may fix cells to a surface, therefore reducing the effect of an experimental process to remove or damage those cells. This was found not to be the case for samples undergoing a detonation as there was no difference in the resultant post-detonation profiles between the stained samples, stained prior to detonation, and unstained samples. The comparison of data from previously performed research, within an enclosed explosives chamber, to real-world outdoor detonation events in a rural and dusty environment was investigated. It was found that there was a significant difference between the environments for the aluminium but not for the battery or electrical tape substrates indicating that environment has the potential to influence STR success through the introduction of PCR inhibitors; humic acid within rural natural dust was introduced here. No difference was observed in cell loss due to the detonation between environments and the dirt within the PCR was higher in the 'outdoor' samples. The effect on cellular retention and damage due to the sample's distance from the charge has been thoroughly investigated through incremental 100 mm exposure. Distance from the charge was found to affect every metric analysed; these being the cell loss from samples, the number of alleles amplified in resultant direct PCR profiles, and the total RFU of the subsequent profiles. These data outline the importance of this work allowing results to be assessed and triage decisions be made accordingly. The analysis of wood, PVC pipe, a mobile phone with rubber buttons, a SIM card, and a circuit board showed that none of these samples at 400 mm from the charge caused substrate specific PCR inhibition. On-site collection teams do not need to triage collection based on these sample types as there was no significant difference observed in their ability to return DNA profiling data. Surface area and inhibitor presence are key variables to consider when determining STR processing workflow for post-detonation samples as for samples with larger surface areas within the outdoor environment PCR post-extraction is preferential to direct PCR.
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Affiliation(s)
- Belinda Martin
- College of Science and Engineering, FlindersUniversity; Biological Sciences Building, 5042 Bedford Park, South Australia, Australia.
| | - Todd Kaesler
- College of Science and Engineering, FlindersUniversity; Biological Sciences Building, 5042 Bedford Park, South Australia, Australia
| | - K Paul Kirkbride
- College of Science and Engineering, FlindersUniversity; Biological Sciences Building, 5042 Bedford Park, South Australia, Australia
| | - Adrian Linacre
- College of Science and Engineering, FlindersUniversity; Biological Sciences Building, 5042 Bedford Park, South Australia, Australia
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Hughes DA, Szkuta B, van Oorschot RAH, Conlan XA. "Technical Note:" Optimisation of Diamond™ Nucleic Acid Dye preparation, application, and visualisation, for latent DNA detection. Forensic Sci Int 2021; 330:111096. [PMID: 34794062 DOI: 10.1016/j.forsciint.2021.111096] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 10/13/2021] [Accepted: 11/01/2021] [Indexed: 11/19/2022]
Abstract
A targeted sampling approach of latent DNA, deposited when a person makes contact with a surface, can prove challenging during crime scene or evidence processing, with the sampling of latent DNA often relying on the expert judgement from crime scene officers and forensic examiners. As such, the ability to use the quick and robust screening tool Diamond™ Nucleic Acid Dye (DD) was explored, with a focus on the visualisation of latent DNA on non-porous substrates, namely polypropylene, acrylic, aluminium, PVC composite material, glass, and crystalline silicon. The application of DD was performed according to methods reported in literature, where 10 µL of the dye solution (20-fold dilution of DD in 75% EtOH) was applied onto a variety of non-porous substrates via a micropipette and then subsequently visualised using a portable fluorescence microscope. It was discovered that there was scope for improvement in the reported methods due to the observation of crystal formations on all test substrates upon drying of the DD, resulting in the impaired visualisation of latent DNA and fingerprint detail. Thus, changes to the EtOH water ratio of the dye solution, and changes to the mode of dye application from a micropipette to a spray application, were explored to improve the drying time of the dye and mitigate the formation of crystals. While changes to the EtOH water ratio did not improve the overall drying time, the mode of dye application enhanced visualisation, with a spray application eliminating the formation of crystals no matter the EtOH water ratio. Visualisation with a portable Dino-Lite and Zeiss Widefield fluorescence microscope were also explored, with the Zeiss Widefield fluorescence microscope proving to be useful in whole print imaging and a more efficient imaging tool in a laboratory setting.
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Affiliation(s)
- Deborah A Hughes
- Deakin University, School of Life and Environmental Sciences, Geelong, Victoria, Australia
| | - Bianca Szkuta
- Deakin University, School of Life and Environmental Sciences, Geelong, Victoria, Australia; Office of the Chief Forensic Scientist, Victoria Police Forensic Services Centre, Macleod, Victoria, Australia
| | - Roland A H van Oorschot
- Office of the Chief Forensic Scientist, Victoria Police Forensic Services Centre, Macleod, Victoria, Australia; School of Molecular Sciences, La Trobe University, Bundoora, Victoria, Australia
| | - Xavier A Conlan
- Deakin University, School of Life and Environmental Sciences, Geelong, Victoria, Australia.
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