COMPARISON OF COPAN 4N6FLOQSWABSTM TO SWABS CURRENTLY IN USE FOR CRIME SCENE EVIDENCE COLLECTION

INTRODUCTION

The ability to properly collect and transport biological material from crime scenes is important for samples preservation for successful forensic DNA detection and profiling. Crime scene samples are typically collected with DNA-Free coeon swabs, which raise two concerns. One, the ability of the collection device to absorb and preserve biological materials, the other how well the human cells are preserved on the device until DNA examination. Copan 4N6FLOQSwabsTM (4N6FS) and Nucleic Acid Optimizer (NAOTM) are innovative devices for crime scene evidence Collection. The 4N6FS are consisting of nylon fiber strands attached to molded plastic, and have high hydrophilic activity that allows efficient sample collection and release (Fig. 1).

NAOTM consisting of a semi-permeable basket, inserted in a 2 ml microtube, is used with the 4N6FS to efficiently release all sample. 4N6FS and NAOTM are produced only by profiled staff, are ETO treated and free of detectable DNAse, RNAse and free of amplifiable human DNA. 4N6FS are produced for Genetics and Crime scene, the latter treated with a bacteria static agent to prevent microbial proliferation.

OBJECTIVES

Compare the 4N6FLOQSwabsTM to the swabs currently in use for traces collection on different materials or objects retrieved from crime scene for investigations .
Evaluate the performance of the 4N6FLOQSwabsTM used dry or wet and with and without the NAOTM for touch DNA collection.
Test preservation capability of 4N6FLOQ Swabs over time.

MATERIAL AND METHOD

Traces (N=200) of different nature were selected. For each kind of trace, one were collected using the 4N6FLOQSwabTM and another with the swabs currently in use. Samples were divided according to the nature of the trace and extracted using different DNA extraction methods: Biorobot EZ1 (Qiagen), Maxwell 16 (Promega) and Chelex 100 (Bio-Rad). DNA was quantified with QuantifilerDuo Real Ame PCR and amplified with NGM SElectExpress on Veriti 96 Well Thermal Cycler. Fragments were then disAnguished using ABI 3500xL.

A total number of 50 mock samples for fresh body fluids, dry body fluids and touch DNA were prepared and collected using wet 4N6FLOQSwabsTM, wet 4N6FLOQSwabsTM with NAOTM basket, dry 4N6FLOQSwabsTM and swabs current in use. Sample were extracted using biorobot EZ1, quantified using QuantifilerDuo DNA quantificaAon kit, amplified with NGM Select Express and run on ABI 3500xL.

RESULTS AND CONCLUSION

Data obtained from analyses on the 200 selected traces demonstrated an increased recovery efficiency of biological material by the N6FLOQSwabsTM compared to the swabs currently in use, especially when tested with the NAOTM basket. This is confirmed for all DNA extracAon methods. Touch DNA collected on hats, gloves and shirts using 4N6FLOQSwabsTM and other swabs were compared and results shows an improve of recovery and sensitivity for Copan swabs against swabs currently used, for touch DNA traces.

Wet and dry 4N6FLOQSwabTM were compared for the collection of blood, saliva and semen traces, wet or dry, and sweat traces; evidence shows that wet swabs are beer for the collection of body fluids while dry one are beer for touch DNA. In every situation recovery using 4N6FLOQSwabsTM is greater than swabs current in use.

At last 4N6FLOQSwabsTM were used to collect different body fluids and, left at room temperature for a maximum of 21 days, were analyzed every 7 days to evaluate the capability of DNA integrity preservation. Quantification results demonstrated that the quantity of biological material remain almost the same during the analyzed period, thanks to antimicrobial treatment of 4N6FLOQSwabsTM. The 4N6FS was then compared to other swabs provided with active drying agent for antimicrobial activity.