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Integrated Sample Cleanup and Capillary Array Electrophoresis Microchip for Forensic Short Tandem Repeat Analysis

NCJ Number
Forensic Science International: Genetics Volume: 5 Issue: 5 Dated: November 2011 Pages: 484-492
Date Published
November 2011
9 pages

A twelve-lane capillary array electrophoresis (CAE) microsystem is developed that utilizes an efficient inline capture injection process together with the classical radial microfabricated capillary array electrophoresis (ìCAE) format for high-sensitivity forensic short tandem repeat (STR) analysis.


Biotin-labeled 9-plex STR amplicons are captured in a photopolymerized gel plug via the strong binding of streptavidin and biotin, followed by efficient washing and thermal release for CE separation. The analysis of 12 STR samples is completed in 30 min without any manual process intervention. A comparison between capture inline injection and conventional cross injection demonstrated at least 10-fold improvement in sensitivity. The limit-of-detection of the capture-CAE system was determined to be 35 haploid copies (17-18 diploid copies) of input DNA; this detection limit approaches the theoretical limits calculated using Poisson statistics and the spectral sensitivity of the instrument. To evaluate the capability of this microsystem for low-copy-number (LCN) analysis, three touch evidence samples recovered from unfired bullet cartridges in a pistol submerged in water for an hour were successfully analyzed, providing 53, 71, and 59 percent of the DNA profile. The high-throughput capture-CAE microsystem presented here provides a more robust and more sensitive platform for conventional as well as LCN and degraded DNA analysis. (Published Abstract)

Date Published: November 1, 2011