Touch DNA-The prospect of DNA profiles from cables.

Metal theft in the railroad industry poses significant challenges to transport investigators. Cable sheaths left behind at crime scenes, if appropriately analysed, could provide valuable evidence in a forensic investigation, but attempts at recovering DNA are not routinely made. Experiments were set up to ascertain the success in DNA recovery from the surface of cable sheaths after deposition of (a) sweat, (b) extracted DNA and (c) fingermarks. Since investigators try to collect fingermarks and often treat the cables with cyanoacrylate fuming (CNA fuming) or wet powder suspensions (WPS) to enhance the marks this study investigated the recovery of DNA from fingermarks pre- and post-enhancement. The double-swab technique and mini-taping were compared as options to recover DNA from the cable sheaths. Results demonstrate that generally, there is no significant difference between using swabs or mini-tapes to recover the DNA from the non-porous cables (p>0.05). It was also illustrated that CNA fuming performed better than WPS in terms of subsequent recovery and profiling of DNA. CNA fuming resulted in an average increase in DNA recovered via swabbing and taping (more than 4× and 8×, respectively), as compared to no treatment, with 50% of the DNA recovered after CNA fuming generating full DNA profiles.

A novel application of real-time RT-LAMP for body fluid identification: using HBB detection as the model.

We report on a novel application of real-time reverse transcription-loop-mediated isothermal amplification (real-time RT-LAMP) to identify the presence of a specific body fluid using blood as a proof-of-concept model. By comparison with recently developed methods of body fluid identification, the RT-LAMP assay is rapid and requires only one simple heating-block maintained at a single temperature, circumventing the need for dedicated equipment. RNA was extracted from different body fluids (blood, semen, saliva, menstrual blood, sweat, and urine) for use in real-time RT-LAMP reaction. The 18S rRNA locus was used as the internal control and hemoglobin beta (HBB) as the blood-specific marker. Reverse transcription and LAMP reaction were performed in the same tube using a turbidimeter for real-time monitoring the reaction products within a threshold of 60 min. HBB LAMP products were only detected in blood and not in any of the other body fluid, but products from the 18S rRNA gene were detected in all the tested body fluids as expected. The limit of detection was a minimum of 10(-5) ng total RNA for detection of both 18S rRNA and HBB. Augmenting the detection of RT-LAMP products was performed by separation of the products using gel electrophoresis and collecting the fluorescence of calcein. The data collected indicated complete concordance with the body fluid tested regardless of the method of detection used. This is the first application of real-time RT-LAMP to detect body fluid specific RNA and indicates the use of this method in forensic biology.

Detection and identification of body fluid stains using antibody-nanoparticle conjugates.

Body fluids are considered one of the most important evidence types in forensic casework. The presence and location of blood, semen and saliva can provide crucial information to investigators. Current practice relies on an accurate visual examination followed by the use of presumptive tests to determine the identity of the body fluid type. Further laboratory based tests are required to unequivocally confirm the identity of a stain. Body fluid stains can be difficult to detect with the naked eye, particularly on dark backgrounds and hence vital evidence may be overlooked. Current methods are fluid-type specific, with a separate, and different, test required for each body fluid. The laborious nature of such analysis and the impossibility of being carried out at the crime scene, leads to a delay in the investigation process that could prove detrimental to the solving of the case. Hence, there is a need for sensitive, specific and direct methods which can simultaneously detect, differentiate, and locate human fluids on items of forensic evidence. Here, we describe the preparation of functionalized iron oxide nanoparticles conjugated to antibodies specific to blood and saliva components and their use in detecting small traces against non-contrasting substrates including glass, ceramic tile, paper and black fabric. The advantage of our technique is that it can simultaneously detect blood and saliva and can spatially locate and differentiate these body fluid types. Most importantly, our technology, which exploits the superparamagnetic properties of iron oxide nanoparticles, works in situ with no need to remove the body fluid stains for testing and with no washing steps and does not interfere with downstream DNA profiling. Thus, our technology represents a novel and effective alternative to existing methods.

Illuminating touch deposits through cellular characterization of hand rinses and body fluids with nucleic acid fluorescence.

Forensic DNA typing from touched or handled items in routine casework is increasing as the sensitivity of detection techniques improves. Our understanding of the cellular/acellular content of touch deposits and the origins of the DNA therein is still limited. This work explores the cellular content of rinses from washed and unwashed hands, as well as saliva, nasal and eye washes which could be sources of transferred DNA onto hands. Flow cytometry and microscopic examination were used to detect granularity, size and nucleic acid fluorescence data. Cellular content did not vary significantly within an individual, although some differences were observed between donors. Saliva contained populations of nucleated epithelia as well as smaller cells and debris, all positive for DNA. Hand rinses consisted almost entirely of anucleate corneocytes, many of which also stained positive for nucleic acids. These data raise questions about shed corneocyte DNA content previously assumed to be negligible.

Synthesis, characterisation and intracellular imaging of PEG capped BEHP-PPV nanospheres.

Aqueous dispersions of poly(ethylene glycol) (PEG) capped poly[2-(2',5'-bis(2''-ethylhexyloxy)phenyl)-1,4-phenylene vinylene] (BEHP-PPV) nanospheres with an average particle diameter of 13 nm have been synthesised by a miniemulsion route and used in simple intracellular imaging experiments.

Application of fluorescent substrates to the in situ detection of prostate specific antigen.

The forensic identification of body fluids frequently presents an important source of genetic material and investigative interpretation. However, presumptive testing techniques presently employed in the discrimination of biological fluids are subject to criticism for poor specificity, lack of fluid localisation ability and detrimental effects on DNA recovery rates. The recognition of fluid-specific biomarkers by fluorogenic substrates may provide a novel resolution to these issues but research has yet to establish any pertinent in situ fluid detection applicability. This study therefore utilises a fluorogenic substrate (Mu-HSSKLQ-AFC) specific to the seminal protein prostate specific antigen in an effort to detect human semen deposited on a number of surfaces typical to criminal investigation. The ability of fluorescent fluorogenic substrates to simultaneously identify and visualise biological fluids in situ is demonstrated for the first time, whilst the production of complete STR profiles from fluid sources is also confirmed to be completely unaffected by substrate application.

The recovery of latent fingermarks and DNA using a silicone-based casting material.

There are many techniques available for the recovery of fingermarks at scenes of crime including the possibility of taking casts of the marks. Casts can be advantageous in cases where other destructive recovery techniques might not be suitable, such as when recovering finger marks deposited on valued or immobile items. In this research, Isomark (a silicone-based casting material) was used to recover casts of finger marks placed on a variety of substrates. Casts were enhanced using cyanoacrylate fuming. Good quality marks were successfully recovered from a range of smooth, non-porous surfaces. Recovery from semi-porous surfaces was shown to be inefficient. DNA was subsequently extracted from the casts using QIAamp Mini extraction kits, amplified and profiled. Full DNA profiles were obtained 34% of samples extracted.

Recovery of DNA and fingerprints from touched documents.

This study investigated the various factors affecting DNA profiling from DNA recovered from fingerprints deposited on paper before and after fingerprint enhancement treatments. The DNeasy plant mini kit (QIAGEN) was found to improve DNA recovery from paper by over 150% compared with the QIAamp mini kit. A significant decrease in the amount of DNA recovered was observed following treatment with DFO and/or Ninhydrin. This decrease in yield did not have a comparably significant effect on the quality of the SGM Plus profiles. Furthermore, this study found that whilst certain paper types, such as newspaper, magazine and filter paper allowed for the good recovery of DNA, common office paper and white card, strongly interfered with the recovery of DNA resulting in poor quality profiles.