Identification and characterization of individual airborne volcanic ash particles by Raman microspectroscopy

Impact of biomass induced black carbon particles in cascading COVID-19

We explore the association of biomass-induced black carbon aerosolized virus with COVID-19 in one of the top-ranked polluted hot spot regions of the world, Delhi, at the time when other confounding factors were almost stable and the pandemic wave was on the declining stage. Delhi was worst affected by COVID-19. However, when it was fast returning back to normal after about 6 months with minimum fatalities, it suddenly encountered a reversal with a 10 fold increase in infection counts, coinciding with the onset of the stubble burning period in neighbouring states. We hereby report that the crop residue burning induced lethal aged Black carbon-rich particles which engulfs Delhi during the post-monsoon months of October-November are strongly associated with COVID-19 and largely responsible for the sudden surge. It is found that the virus efficacy is not necessarily related to any particulates but it is more of source-based toxicity of its component where the virus is piggybacking. We conclude that the aged biomass BC particles tend to aggregate and react with other compounds to grow in size, providing temporary habitat to viruses leading to the rapid increase in COVID-19 cases which declined after the crop burning stopped.

Nondestructive Chemical Analysis of the Iron-Containing Protein Ferritin Using Raman Microspectroscopy

Ferritin is a ubiquitous intracellular iron storage protein of animals, plants, and bacteria. The cavity of this protein acts like a reaction chamber for natural formation and storage of nano-sized particles via biomineralization. Knowledge of the chemical composition and structure of the iron core is highly warranted in the fields of nano technologies as well as biomolecules and medicine. Here, we show that Raman microspectroscopy (RM) is a suitable nondestructive approach for an analysis of proteins containing such nano-sized iron oxides. Our approach addresses: (1) synthesis of suitable reference materials, i.e., ferrihydrite, maghemite and magnetite nanoparticles; (2) optimization of parameters for Raman spectroscopic analysis; (3) comparison of Raman spectra from ferritin with apoferritin and our reference minerals; and (4) validation of Raman analysis by X-ray diffraction and Mössbauer spectroscopy as two independent complementary approaches. Our results reveal that the iron core of natural ferritin is composed of the iron(III) hydroxide ferrihydrite (Fe₂O₃ ∙ 0.5 H₂O).

Biocatalytic green alternative to existing hazardous reaction media: synthesis of chalcone and flavone derivatives via the Claisen–Schmidt reaction at room temperature

Herein, two novel agro-food waste products from banana peels were used to synthesize chalcone and flavone derivatives at room temperature under solvent free conditions.

Applications in: Environmental Analytics (fine particles)

Micro Raman spectroscopy has been applied very early in environmental analytics. However, until now the field of application is quite limited. The main reasons for the low acceptance are high cost of the method and the low throughput. New developments in technology lead to cheaper instrumentation. Automation of Raman microscopy of particles might be a solution for a higher throughput and a broader application in environmental analytics. A more detailed analysis of aerosols and microplastic is good examples that could benefit from this development.

A hypothesis of sudden body fluid vaporization in the 79 AD victims of Vesuvius

In AD 79 the town of Herculaneum was suddenly hit and overwhelmed by volcanic ash-avalanches that killed all its remaining residents, as also occurred in Pompeii and other settlements as far as 20 kilometers from Vesuvius. New investigations on the victims' skeletons unearthed from the ash deposit filling 12 waterfront chambers have now revealed widespread preservation of atypical red and black mineral residues encrusting the bones, which also impregnate the ash filling the intracranial cavity and the ash-bed encasing the skeletons. Here we show the unique detection of large amounts of iron and iron oxides from such residues, as revealed by inductively coupled plasma mass spectrometry and Raman microspectroscopy, thought to be the final products of heme iron upon thermal decomposition. The extraordinarily rare preservation of significant putative evidence of hemoprotein thermal degradation from the eruption victims strongly suggests the rapid vaporization of body fluids and soft tissues of people at death due to exposure to extreme heat.

The Toxicological Mechanisms of Environmental Soot (Black Carbon) and Carbon Black: Focus on Oxidative Stress and Inflammatory Pathways

The environmental soot and carbon blacks (CBs) cause many diseases in humans, but their underlying mechanisms of toxicity are still poorly understood. Both are formed after the incomplete combustion of hydrocarbons but differ in their constituents and percent carbon contents. For the first time, “Sir Percival Pott” described soot as a carcinogen, which was subsequently confirmed by many others. The existing data suggest three main types of diseases due to soot and CB exposures: cancer, respiratory diseases, and cardiovascular dysfunctions. Experimental models revealed the involvement of oxidative stress, DNA methylation, formation of DNA adducts, and Aryl hydrocarbon receptor activation as the key mechanisms of soot- and CB-induced cancers. Metals including Si, Fe, Mn, Ti, and Co in soot also contribute in the reactive oxygen species (ROS)-mediated DNA damage. Mechanistically, ROS-induced DNA damage is further enhanced by eosinophils and neutrophils via halide (Cl⁻ and Br⁻) dependent DNA adducts formation. The activation of pulmonary dendritic cells, T helper type 2 cells, and mast cells is crucial mediators in the pathology of soot- or CB-induced respiratory disease. Polyunsaturated fatty acids (PUFAs) were also found to modulate T cells functions in respiratory diseases. Particularly, telomerase reverse transcriptase was found to play the critical role in soot- and CB-induced cardiovascular dysfunctions. In this review, we propose integrated mechanisms of soot- and CB-induced toxicity emphasizing the role of inflammatory mediators and oxidative stress. We also suggest use of antioxidants and PUFAs as protective strategies against soot- and CB-induced disorders.

Raman-based microarray readout: a review

For a quarter of a century, microarrays have been part of the routine analytical toolbox. Label-based fluorescence detection is still the commonest optical readout strategy. Since the 1990s, a continuously increasing number of label-based as well as label-free experiments on Raman-based microarray readout concepts have been reported. This review summarizes the possible concepts and methods and their advantages and challenges. A common label-based strategy is based on the binding of selective receptors as well as Raman reporter molecules to plasmonic nanoparticles in a sandwich immunoassay, which results in surface-enhanced Raman scattering signals of the reporter molecule. Alternatively, capture of the analytes can be performed by receptors on a microarray surface. Addition of plasmonic nanoparticles again leads to a surface-enhanced Raman scattering signal, not of a label but directly of the analyte. This approach is mostly proposed for bacteria and cell detection. However, although many promising readout strategies have been discussed in numerous publications, rarely have any of them made the step from proof of concept to a practical application, let alone routine use. Graphical Abstract Possible realization of a SERS (Surface-Enhanced Raman Scattering) system for microarray readout.