Detection of human blood by immunoassay for applications in forensic analysis

Spot tests: past and present

Microchemistry, i.e., the chemistry performed at the scale of a microgram or less, has its roots in the late eighteenth and early nineteenth centuries. In the first half of the twentieth century a wide range of spot tests have been developed. For didactic reasons, they are still part of the curriculum of chemistry students. However, they are even highly important for applied analyses in conservation of cultural heritage, food science, forensic science, clinical and pharmacological sciences, geochemistry, and environmental sciences. Modern pregnancy tests, virus tests, etc. are the most recent examples of sophisticated spot tests. The present ChemTexts contribution aims to provide an overview of the past and present of this analytical methodology.

Surface enhanced Raman scattering for robust, sensitive detection and confirmatory identification of dried bloodstains

785 nm SERS spectra provide rapid, sensitive confirmatory identification of dried bloodstains due to a ferric, high spin heme moiety.

Forensic application of comet assay: an emerging technique

Postmortem interval (PMI) estimation is a recurring problem in the field of forensic medicine. Conventional methods are effective but are insufficient to estimate accurate and precise time of death or PMI. In addition, degradation of biological samples is another major problem in forensic science which affects the investigation process and misleads the result. Some previous studies reported that DNA fragmentation has strong correlation with PMI. DNA fragmentation increased with prolonged PMI. Comet assay is a rapid sensitive, versatile, reliable and cost effective technique that is specifically used for qualitative and quantitative estimation of nuclear DNA fragmentation. Due to this attribute, comet assay can help to estimate accurate and precise time of death for some extent that is for early PMI estimation. In addition, two confounding factors are responsible for DNA fragmentation: (1) micro-organism; (2) environmental condition. Here, comet assay plays a dual role: (1) partially degraded samples get repaired using repair enzyme; (2) accurate time since deposition can be measured without using repair enzyme. Furthermore, this assay can also help to identify potential exposures of environmental-released chemicals/toxicants and its deleterious effects on human population. In this way, comet assay shows its versatile applications that could be useful for forensic investigation. Therefore, with the help of this review, an attempt was made to explore the versatility of comet assay technique for forensic applications and its future perspective.

The development of a method of suspension RNA-FISH for forensically relevant epithelial cells using LNA probes

Messenger RNA profiling is becoming a common method for body fluid identification in forensic science but there are disadvantages when cell mixtures are present from more than one individual. A method that could identify and separate such cell mixtures would simplify downstream analysis. To do this, we have developed a novel method of RNA suspension-fluorescent in situ hybridization (RNA S-FISH) using a locked nucleic acid (LNA) probe for the keratin 10 (KRT10) mRNA that is suitable as a potential marker for epithelial cells. As sample size may be restricted in forensic samples, this method has focused on minimizing cell loss whilst maintaining signal strength. Furthermore, we have shown that it is possible to obtain full DNA profiles from 150 RNA S-FISH labeled cells isolated using laser microdissection.