EM - IUEM - Técnicas Laboratoriais Forenses
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- Application of SERS with raman reporter-labelled metallic nanoparticles for latent fingermark enhancementPublication . Echeonwu, Bobmanuel Chimaroke; Croxton, Ruth S.The importance of human fingermark identification and individualization for forensic purposes cannot be overemphasized. Consequently, the need for robust and effective techniques explains the continued and intensified research in this field of forensics despite the fact that there are already numerous operational techniques available to forensic identification experts. Novel approaches have recently been adopted to understand the chemistry of latent fingermarks and produce reagents targeting some of these constituents of latent fingermarks. Nanotechnology and surface-enhanced Raman spectroscopy (SERS) are gaining more attention in this area of endeavor, where nanoparticle-based reagents are increasingly being developed and optimized for application in latent fingermark enhancement and chemical imaging of such latent fingermarks. In this study, surface-enhanced Raman spectroscopy has been used to investigate the applicability of Raman reporter-labeled metallic nanoparticles to the enhancement of latent fingermarks. Rhodamine 6G and 4-mercaptobenzoic acid have been investigated as Raman reporters adsorbed on either gold or silver nanoparticles. The functionalized nanoparticles were deposited onto latent fingermark samples and characteristic Raman vibrational bands of the reporter molecules when adsorbed on nanoparticles (1076 cm-1 and 1583 cm-1 for 4-mercptobenzoic acid; 610 cm-1, 1360 cm-1 1505 cm-1 and 1648 cm-1 for rhodamine 6G) were monitored and showed very low variability of peak position between samples (coefficient of variation generally < 0.5%). Adsorption of reporter molecules on nanoparticles was characterized using UV-vis absorption spectroscopy as well as the behaviour of characteristic Raman shifts of the molecules which gave an indication of successful adsorption. Rhodamine 6G in this study however had a weak adsorption onto silver nanoparticles as a result of suboptimal amounts of the dye molecule used. Preferential deposition of the Raman reporter-labeled nanoparticles on fingermark ridges was also observed with fingermarks deposited on non-porous surface (glass slide). This study demonstrates the potential for SERS chemical imaging of latent fingermarks based on characteristic SERS vibrational bands from reporter molecules adsorbed on metallic nanoparticles and deposited onto latent fingermarks.
- “Charlie” (buphedrone/ethcathinone) behavioural patterns after stimulated binge administrationPublication . Sola Sancho, Sofía; Lopes, Álvaro TeixeiraSince the entry of XXI century, the consume, availability and variety of new psychoactive substances also called “legal highs” “legal drugs” or “design drugs,” have been rising enormously. This tendency has increased the concern of both, health care providers and legal authorities about this family of drugs. This unique study is a first toxicological approach to a drug named “Charlie”. Effects for a repeated administration of a singular dose of 45mg/kg has been assessed. “Charlie” is a combination of two synthetic cathinones (Buphedrone and Ethcathinone) with no toxicological or behavioural studies done, until the date. For developing the study a binge administration was performed in a ten days study with the combination of the drug with ethanol in a dose of 2g/kg. For the toxicological assessment, adolescent male CD1 mice were used and four behavioural tests were chosen, Functional Observational Battery (FOB), Open Field (OF) test, Marble burying test and T-maze test. Results showed the significant differences between controls and mice under the influence of “Charlie” or under the mixture of “Charlie” and ethanol at all performed tests. The combination cathinone-ethanol showed mayor effects in the variables for FOB and OF than when the drug was administered alone ad different behavioural patterns in Marble and T-Maze tests. The study of the weights and food and water intake before and during the experiments was also assessed and results pointed the variations in weight and food intake during the days of the experiment suffering a marked decrease in those days. With this study it is demonstrated the influence of “Charlie” in the behaviour and physiological conditions of the individuals under its effects by using behavioural tasks for the assess and opening a new “file” in the cathinones behavioural assessment.
- Contribution to portuguese urban fire investigations: forensic fire debris analysisPublication . Oliverio, Stefania; Noronha, João Paulo; Carvalho, AntónioFire scene investigation and fire debris analysis (FDA) are two tightly linked and mutually exclusive key elements of a forensic arson investigation. While the fire scene investigation is performed by a trained fire investigator, FDA is a task undertaken by a fire debris analyst, which is normally a forensic chemist with expert knowledge in analytical chemistry. To solve a case efficiently and successfully, cooperation and information- and knowledge-exchange are necessary, especially since this branch of forensic science is defined as one of the most complex and arduous ones due to the highly destructive nature of fires that severely compromises the integrity of the evidence collected at the crime scene. The task of analysing the fire debris for the detection of ignitable liquid residues (ILRs) is further complicated by the large influence and existence of interfering products. Most ignitable liquids (ILs) are made of hydrocarbons, which are also compounds that have been found in the substrate of common household or construction materials as well as being created during the processes of combustion and pyrolysis. The purpose of this study was to identify and characterize background, combustion and pyrolysis products of commonly encountered substrate materials in fire scenes in Portugal and observe the effects on ILRs identification by using headspace solid-phase micro-extraction linked to gas chromatography-mass spectrometry (HS-SPME-GC-MS). The results show that both the background of the substrates and the combustion and pyrolysis products formed during a fire include many compounds that constitute common ILs, such as alkanes and aromatics, that especially in the presence of low amount of ILRs constitute a problem in the conclusive identification of ILs. Even though detailed analysis of the chromatographic and mass-spectral patterns and the combinations of compounds detected in the materials can avoid misinterpretation, in some cases, awareness and knowledge of interfering products is essential.
- Evaluation of current and novel methods for the storage of DNA-extractsPublication . Sjoukema, Pieterjan; Barroso, Maria Helena; Carvalho, RaquelSecure preservation of DNA-extracts has been an issue at forensic laboratories for a long time. DNA-extracts are commonly stored at either -20°C or -80°C, but storage at these temperatures is not without risk of failure, environment unfriendly and costly. The Laboratório de Polícia Científica (LPC; Forensic Science Laboratory) of the Polícia Judiciária (PJ; Judicial Police) in Lisbon, Portugal is currently looking into new ways of storing their DNA-extracts at room temperature. Both DNAstable® and GenTegra-DNA®, two commercially available products for the storage of DNA-extracts at ambient temperatures, have been evaluated. DNA samples with extremely low concentrations of DNA (0.1 ng/μL, 0.05 ng/μL and 0.025 ng/μL) and DNA-extracts extracted from buccal swabs with the SwabSolution™ kit (Promega, Madison, USA) have been stored in standard polypropylene tubes, DNAstable® tubes and GenTegra-DNA® tubes for 8 days at four different conditions, i.e., -20°C, 4°C, at room temperature and at 60°C. Besides this, randomly selected DNA-extracts that have been stored at -20°C since 2006, 2009 or 2013 have been reanalyzed with the currently at the LPC used techniques in order to assess the level of degradation after long-term storage at -20°C. Results showed that DNA degrades over time at -20°C, with recovery levels found as low as 20% after three years of storage at -20°C. DNAstable® and GenTegra-DNA® both showed to be able to preserve DNA dried at room temperature and 60°C. Given the short period of storage full DNA-profiles have also been obtained from samples stored in standard polypropylene tubes at room temperature. Significant differences were found between DNA-extracts stored at 60°C with either DNAstable® or GenTegra-DNA® and those stored in unprotected tubes, showing that both DNAstable® and GenTegra-DNA® are capable of storing DNA at room temperature for long periods of time with a similar or even higher level of protection compared to those achieved with conventional storage at -20°C. Nevertheless, more research is needed before a switch can be made from frozen storage at -20°C to the storage of DNA-extracts at room temperature with products such as DNAstable® and GenTegra-DNA®.
- The cytotoxic effect of THJ-018 in human neuroblastoma SH-SY5Y cellsPublication . Khosasih, Vivia; Quintas, Alexandre; Costa, Joana Couceiro daSince its first appearing on 2004, synthetic cannabinoidsm the market of the so-called recreational drug, have regained popularity among adolescents and young adults. Current in vitro studies show that synthetic cannabinoids have stringer binding affinity to cannabinoids 1 (CB1) receptor than the Δ9-tetrahydrocannabinal. Therefore, it suggested that synthetic cannabinoids possess stronger psychotropic effect than cannabis. Albeit it has been increasingly abused as the legal alternative of cannabis, the pharmacological and toxicological profiles of synthetic cannabinoids remais poorly understood. One of the earliest synthetic cannabinoids to be identified was JWH-018. This study was performed to explore the toxicological effect of synthetic cannabinoids THJ-018 as the legal analog to JWH-018 on human cells model. SH-SY5Y cell lineage was used as the human cell model in this study since it has been reported to express cannabinoids 1 receptor (CB1). Seven designated concentrations of synthetic cannabinoids THJ-018, such as 1 μM, 5 μM, 10 μM, 25 μM, 50 μM, 75 μM and 100 μM were exposed for 24 hours to human neuroblastoma SH-SY5Y cell lineage. The cell viability was evaluated by performing the 3-(4,5-dimethylthiazolyl-2)-2,5 diphenyltetrazolium bromide (MTT) assay. The MTT results on SH-SY5Y cells show a statiscally significant increase on cell viability (* p<0.05, ** p<0.01 or *** p<0.001) for the concentration of 10, 25, 50, 75 and 100 μM of THJ-018. This results indicated that the THJ-018 is not toxic to the SH-SY5Y cell line. Furthermore, the cytotoxicity effect of THJ-018 combustion product, which is performed to evaluate the mimicry of the process of smoking as the common route of administration for synthetic cannabinoids, show a decrease of cell viability when SH-SY5Y cell exposed with THJ-018 combustion product.