法医学杂志最新文献

New psychoactive substances (NPS) have the characteristics of rapid turnover, wide varieties, and high abuse potential. It has become a major threat to global public safety. Currently, the forensic identification of NPS faces certain challenges in detection methods for effectiveness, sensitivity, accuracy and resistance to matrix interference. Novel functional materials (NFM), with their high specific surface area, designability, specific recognition capability and signal amplification effects, provide a new path for advancing rapid detection techniques for NPS. This paper systematically reviews the innovative applications of NFM in the rapid detection of NPS over the past decade. By summarizing and analyzing the research and applications of NFM in laboratory detection and on-site rapid screening, it outlines the characteristics and advantages of different types of materials. Combined with the development trends of NFM in intelligent material design, interdisciplinary integration and portable integrated devices, it provides theoretical references for the development of rapid detection methods for NPS, which is conducive to improving the rapid detection ability of NPS in "anti-drug combat".

Objectives: To obtain differential spectral characteristics of etomidate and its structural analogues, and to establish a rapid identification method using surface-enhanced Raman spectroscopy (SERS) combined with machine learning algorithms for distinguishing etomidate and its analogues.

Methods: Silver nanoparticles (AgNPs) were used as the SERS substrate to collect SERS spectra of etomidate, metomidate, propoxate, and isopropoxate at two concentrations of 1×10^-4 and 1×10^-5 mol/L. SERS spectra were also obtained from blood and urine samples containing 1×10^-5 mol/L of etomidate, metomidate, propoxate, and isopropoxate, as well as from confiscated e-cigarette oil containing etomidate. Uniform manifold approximation and projection (UMAP) was employed for nonlinear dimensiona-lity reduction and visualization, and a classification model based on the XGBoost algorithm was constructed to enable discriminant analysis of these four structurally highly similar compounds.

Results: Minor characteristic peak shifts (5-3 cm^-1) were identified in the range of 1 398-811 cm^-1. Qualitative identification of the compounds in serum, urine and e-cigarette oil samples was achieved without pretreatment. After UMAP dimensionality reduction, distinct clustering separation among different substances was observed. The XGBoost model achieved 100% classification accuracy on the test set. Feature weight analysis revealed that C-N stretching vibration (841 cm^-1), C=O stretching vibration (1 367 cm^-1), and C-O-C asymmetric vibration (1 049 cm^-1) were the key spectral bands for discrimination.

Conclusions: The combination of SERS and machine learning can effectively amplify subtle differences in molecular structures, enabling rapid and accurate identification of etomidate and its analogues. This approach is suitable for on-site rapid screening in forensic toxicology.

Objectives: To compare the application effects of plankton multiplex polymerase chain reaction-capillary electrophoresis (PCR-CE), SYBR Green Ⅰ real-time quantitative PCR (qPCR) and microwave digestion-vacuum filtration-automated scanning electron microscopy (MD-VF-Auto SEM) in the diagnosis of drowning.

Methods: Lung, liver and kidney tissues from 212 drowned corpses and 30 non-drowned corpses were examined respectively by the three drowning-related plankton testing methods, and the detection rates of plankton in each tissue by three methods were compared.

Results: In drowned corpses, the total detection rates of PCR-CE, qPCR, and MD-VF-Auto SEM were 93.9%, 96.2%, and 95.3%, respectively, with no statistically significant difference (P>0.05). The detection rate of lung tissue by MD-VF-Auto SEM (100%) was higher than those of PCR-CE and qPCR (P<0.05), and there was no significant difference in the detection rates of the three methods in liver or kidney tissues (P>0.05). In non-drowning corpses, a small number of diatoms (less than 10 cells/10 g) were detected by MD-VF-Auto SEM method, only in liver and kidney tissues, while the other two methods yielded negative results for all tissues.

Conclusions: All three methods have good efficacy in the examination of drowned corpses. The MD-VF-Auto SEM method directly observes diatom morphological characteristics through scanning electron microscopy, and the qualitative and quantitative analyses are intuitive and accurate. It has great advantages in the examination of difficult degradation samples. The PCR-CE method and qPCR method have a low sample demand (0.5 g), are easy to operate and have short detection time (4-7 h). They are easy to be applied in the grassroots departments and are suitable for the rapid determination of drowned corpses in routin cases. The combination of the two DNA methods with the MD-VF-Auto SEM method can increase the detection rate of plankton, ensuring the reliability of examination results. This combined use is of significant importance in the application of drowning diagnosis.

Objectives: To verify the efficacy of a domestic human DNA quantification kit based on real-time fluorescence quantitative PCR in detecting the total human DNA concentration, male DNA concentration in mixed male/female DNA samples, the degree of DNA degradation and inhibitor tolerance.

Methods: Samples with different concentrations, different male/female ratios, different concentrations of inhibitors, and different degradation degrees were tested using the domestic human DNA quantification kit based on real-time fluorescence quantitative PCR. This kit was compared with a similar product on the market and was applied to the detection of DNA from real cases.

Results: This human DNA quantification kit can effectively detect human DNA as low as 0.001 65 ng/μL, and 6.25 pg/μL of male DNA in mixed samples with a male-to-female ratio of 1∶15 000. Even when the sample contains as high as 400 ng/μL of humic acid or 1 000 μmol/L of hemin alone, the DNA concentration can still be accurately detected. The degradation index can effectively characterize the degradation degree of the sample. This kit has been successfully applied in forensic practice.

Conclusions: This human DNA quantification kit is accurate and reliable in detection. It can accurately reflect the degradation of DNA and inhibitor tolerance. It has good performance in quantitative accuracy, determination of the male/female ratio in mixed samples, and inhibitor tolerance. It has application potential in forensic case examination.