This project developed an integrated PCR sample cleanup and preconcentration process for forensic short tandem repeat (STR) analysis, using a streptavidin-modified photopolymerized capture gel injector for microchip capillary electrophoresis (μCE).
PCR samples generated with one biotinylated primer and one fluorescent primer provided the input to the streptavidin-based affinity capture-μCE device. Monoplex PCR samples processed by the device exhibited ∼10- to 50-fold increased fluorescence intensities, and DNA profiles generated using 9-plex STR samples displayed ∼14- to 19-fold higher signal intensities compared to those analyzed using traditional cross injection. Complete STR profiles were obtained with as few as 25 copies of DNA template using the capture-μCE device. Four DNA samples with various degrees of degradation were also tested. Samples analyzed using the capture-μCE device resulted in a significant increase of successful allele detection. The ability of the capture-μCE device and method to remove contaminating ions, to concentrate the sample injection plug, and to eliminate electrokinetic injection bias provides a powerful approach for integrating sample cleanup with DNA separation. (publisher abstract modified)