Identification and characterization of textile fibers by thermal analysis

Textile fibers are ubiquitous in the sense that they are present in the fabric of clothing, furniture, floor and wall covering. A remarkable variety of textile fibers with different chemical compositions are produced for many different commercial applications. As fibers are readily transferred they are frequently recovered from crime scenes as trace evidence and may provide useful forensic information for identification purposes. The objective of the experiment described in this paper is to evaluate specific thermal analysis techniques (DSC and TGA) as means by which textile fibers or cloth fragments may be reliably identified using experimentally simple and reproducible instrumental methods. The results are analyzed to determine whether these techniques may serve to identify different textiles on the basis of their thermal behavior, to decide if sample matching is possible and to evaluate detection limits for the sample-instrument combination used.Fundação para a Ciência e a Tecnologia (FCT

Rapid, sequence-specific detection of unpurified PCR amplicons via a reusable, electrochemical sensor

We report an electrochemical method for the sequence-specific detection of unpurified amplification products of the gyrB gene of Salmonella typhimurium. Using an asymmetric PCR and the electrochemical E-DNA detection scheme, single-stranded amplicons were produced from as few as 90 gene copies and, without subsequent purification, rapidly identified. The detection is specific; the sensor does not respond when challenged with control oligonucleotides based on the gyrB genes of either Escherichia coli or various Shigella species. In contrast to existing sequence-specific optical- and capillary electrophoresis-based detection methods, the E-DNA sensor is fully electronic and requires neither cumbersome, expensive optics nor high voltage power supplies. Given these advantages, E-DNA sensors appear well suited for implementation in portable PCR microdevices directed at, for example, the rapid detection of pathogens