test forensic

Forensics

 


Dr. Katja ANSLINGER, from Ludwig-Maximilians-University of Munich, discusses her latest findings in the field of single-cell forensics using the DEPArray NxT

 

Mixed samples are the last unresolved issue in forensic genetic. 

Current approaches to resolve mixed biological evidence profiling include the chemical reduction of one type of cells (differential lysis) or the use of informatics algorithms to deconvolute mixed profiles. These methods are limited however to mixtures of sperm/epithelial cells and to a limited range of cell ratios.

DEPArray technology is particularly well suited for forensic samples thanks to the very high precision of digital sorting and the very limited requirement of sample input. Few hundred cells can be sufficient to load a chip and single cells can be identified and recovered with high precision thanks to the use of immunofluorescent markers and imaging.

With DEPArray we introduce three innovative solutions for mixed forensic sample analysis:

  • Simultaneous cell identification and profiling: The possibility to determine, in a mixed sample, which is the STR profile corresponding to each type of cell
  • Pure cell analysis: sufficient to resolve cases of 2 contributors where the victim and the perpetrator contribute with a different cell type (sperm-epithelial, blood-epithelial, blood-sperm)
  • Single cell analysis: for more complex cases where multiple contributors share the same type of cells (blood-blood, sperm-sperm, saliva-saliva)

STR

Single cell profile of a blood cell isolated from a swab of a knife found on the crime scene of a murder. (Anslinger et al, Rechtsmedizin, Dec 2018  https://doi.org/10.1007/s00194-018-0291-1)

 

DEPArray Forensic Sample Prep Kit

Scatola_DEPArray_Forensic_Sample_Prep_Kit.jpgWith the ability to analyze even minute mixed biological evidence, the DEPArray system can separate epithelial cells, white blood cells, and sperm cells, and recover 100% pure pools of cells for standard forensic analysis. 

The newly developed DEPArray Forensic Sample Prep Kit streamline the sample preparation step before DEPArray sorting with a labor-saving and standardize procedure. The kit includes all the reagents to process the sample from the evidence support material to the DEPArray cartridge and has been specifically designed for the staining of epithelial, sperm and white blood cells before DEPArray sorting.

The workflow below allows the recovery of multiple groups of 100% pure samples for clear-cut genetic profiling.

flusso_forensic

 

Compatible with Existing STR Kits

Cells selected, isolated, and collected by the DEPArray system are compatible with DNA-based human identification kits, instrumentation, and software from a variety of suppliers.

Single-Cell Precision

Digital sorting combines the power of immunofluorescence markers with image based selection to secure the highest precision and sensitivity in the isolation of cells of the desired kind and with 100% purity.

 

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