Silver Nanoparticle Films Obtained by Convective Self-Assembly for Surface-Enhanced Raman Spectroscopy Analyses of the Pesticides Thiabendazole and Endosulfan

Pesticides pose a great threat to human health and their rapid detection has become an urgent public safety issue engaging the scientific community to search for fast and reliable detection techniques. In this context, Surface Enhanced Raman Spectroscopy (SERS) has emerged as a valuable detection and analysis tool due to its high sensitivity and selectivity, proving its suitability for the food industry and environmental monitoring applications. Here, we report on the fabrication of colloidal silver nanoparticle (AgNP) films by convective self-assembly (CSA) on solid planar substrate and their use for the SERS analyses of two types of pesticides, the fungicide thiabendazole (TBZ) and the insecticide α-endosulfan (α-ES). Electron microscopy shows that these nanoparticle films are dense, highly compact, and uniform across several mm² areas. The SERS efficiency of the fabricated AgNP films is evaluated using a well-known Raman probe, p-aminothiophenol, for multiple excitation laser lines (532 nm, 633 nm, and 785 nm). The films exhibit the largest SERS enhancement factors for 785 nm excitation, reaching values larger than 10⁵. Thiabendazole could be readily adsorbed on the AgNPs without any sample surface functionalization and detected down to 10⁻⁶ M, reaching the sub-ppm range. Endosulfan, a challenging analyte with poor affinity to metal surfaces, was captured near the metal surface by using self-assembled alkane thiol monolayers (hexanethiol and octanethiol), as demonstrated by the thorough vibrational band analysis, and supported by density functional theory (DFT) calculations. In addition, principal component analysis (PCA) based on SERS spectra offers significant leverage in discrimination of the molecules anchored onto the metallic nanostructured surface. This present study demonstrates the utility of self-assembled colloidal nanoparticle films as SERS substrates for a broad range of analytes (para-aminothiophenol, thiabendazole, α-endosulfan, and alkanethiols) and contributes to the development of SERS-based sensors for pesticides detection, identification and monitoring.

Prognostic implications of Neutrophil Extracellular Traps in coronary thrombi of patients with ST-elevation myocardial infarction

AIMS

The mechanisms of coronary thrombosis can influence prognosis after STEMI and allow for different treatment groups to be identified; an association between neutrophil extracellular traps (NETs) and unfavorable clinical outcomes has been suggested. Our aim was to determine the role played by NETs in coronary thrombosis and their influence on prognosis. The role of other histological features in prognosis and the association between NETs and bacteria in the coronary thrombi were also explored.

METHODS AND RESULTS

We studied 406 patients with STEMI in which coronary thrombi were consecutively obtained by aspiration during angioplasty between 2012 and 2018. Analysis of NETs in paraffin-embedded thrombi was based on the colocalization of specific NET components by means of confocal microscopy. Immunohistochemistry stains were used to identify plaque fragments. Fluorescence in situ hybridization was used to detect bacteria. NETs were detected in 51% of the thrombi [NET density, median (IQR): 25% (17-38%)]. The median follow-up was 47 months (95% CI 43-51); 105 (26%) patients experienced major adverse cardiac events (MACE). A significant association was found between the presence of NETs in coronary aspirates and the occurrence of MACE in the first 30 days after infarction (HR 2.82; 95% CI 1.26-6.35, p=.012), mainly due to cardiac deaths and stent thrombosis.

CONCLUSIONS

The presence of NETs in coronary thrombi was associated with a worse prognosis soon after STEMI. In some patients, NETs could be a treatment target and a feasible way to prevent reinfarction.