Particle analysis and elemental mapping are formidable techniques that have revolutionized the domains of materials science, nanotechnology, and forensic research. These techniques have provided valuable insights into the morphology, arrangement, and characteristics of novel materials. These methods can be performed subsequently to obtain essential information, including the type and number of particles as well as the distribution of constituent materials.
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Applications in Microbiology
Maintaining metal homeostasis within biological systems is important in sustaining essential functions such as the immune response, metabolism, and intracellular signaling. Additionally, imbalanced and excessive levels of specific elements have been associated with various serious diseases. The examination of elemental distribution in mammalian cells and tissues assumes a critical role in advancing our comprehension of significant human diseases.
A recent article in Analytical and Bioanalytical Chemistry states that until a short while ago, the acquisition of quantitative elemental information primarily relied on evaluating aggregate groups of cells, leading to averaged outcomes. This approach required assessment of the bulk sample utilizing a well-defined spectroscopic method, with solution ICP-MS (inductively coupled plasma-mass spectrometry) being the most prevalent technique employed for this purpose.
The precision of SP-ICP-MS measurements hinges on the instrument's capability to incorporate and introduce individual particles. The initiation of accurate SP-ICP-MS examination involves the meticulous selection of the ideal cell concentration.
This concentration should be adequately minimal to facilitate the entry of single cells into the plasma yet sufficiently substantial to secure a statistically meaningful count of peaks. Its effectiveness renders it not only valuable for determining metal density but also highlights its utility in showcasing peak distribution at various positions, thus confirming its utility in elemental mapping.
LIBS emerges as a favorable option for bioanalytical applications, setting it apart from methods that demand extensive sample preparation. Initial investigations have illustrated that LIBS serves as a sensitive tool for dissecting the elemental composition of biological samples in their solid state.
Furthermore, LIBS has found utility in executing elemental mapping of hair tissue. While LIBS applications have been primarily focused on tissue-level elemental analysis and mapping, rather than the more challenging single-cell analysis that necessitates heightened sensitivity in the femtogram per cell range, the possibility of extending LIBS applications to single-cell scrutiny merits deeper exploration.
The potential integration of nanoscale-LIBS imaging holds the promise of heightened sensitivity, capitalizing on both femtosecond laser-based sampling and nanosecond laser-driven emission enhancement.
Analysis and Mapping of Tire Wear Particles (TWP)
In recent times, there has been a substantial surge in the attention directed toward the presence and concentration of tire wear particles, often termed tire/road wear particles (TWP), within the environment. This mounting interest within the realm of air pollution management has coincided with a noteworthy decline in emissions stemming from exhaust fumes, road traffic, and other sources.
As per the article published in Science of the Total Environment, the mapping of TWP presents a formidable challenge owing to the absence of specific markers and the prevalence of analytically intricate low concentrations. This complexity is further compounded by the assorted chemical and morpho-textural variations within TWP arising from the interplay between tires and road surfaces.
Unlike conventional methods, automated single-particle SEM/EDX analysis can harness the pervasive heterogeneity inherent in environmental TWP as a distinctive parameter for their discernment and quantification.
As part of a comprehensive PM10 characterization, sample collection was conducted in two Swiss cities. A machine learning (ML) based model was devised to categorize and spatially represent the collected airborne samples. The average percentage of TWP per sampling period (PM80–10) at the urban site Bern Bollwerk stood at 19.5% (192 particles per sample). Conversely, the urban background site Zürich Kaserne reported an average TWP percentage of 3.3% (41 particles).
In terms of elemental distribution, the PM80-10 fraction at Bern Bollwerk yielded a TWP concentration of 11.23 μg/m3 (annual average), constituting 83% of the total identifiable TWP within this location. The remaining 17% of TWP was confined to the PM10-1 fraction.
When considering mass concentrations, it was evident that the particle size distribution in Bern Bollwerk was broader. This particular mapping could be attributed to the much more significant influence of coarser particles compared to Zürich Kaserne, where a narrower size distribution was observed.
This approach presents a valuable complement to alternative TWP quantification methodologies, particularly when factors such as size, morphology, and a comprehensive overview of various particle types within the same sample come into play.
Utilization in NanoTechnology
Within the domain of nanotechnology, a comprehensive comprehension of particle size distribution and elemental composition is necessary for enhancing the properties of nanomaterials. By integrating particle analysis alongside elemental mapping, researchers are equipped to meticulously manage the synthesis of nanoparticles.
Metallic nanoparticles (NPs) hold promise as potential antimicrobial agents, attributed to their diminutive dimensions and noteworthy surface-to-volume ratio. Specifically, titanium dioxide has demonstrated augmented photo-electrochemical proficiency and effective photocatalytic attributes.
In the latest article published in BMC Microbiology, researchers utilized particle analysis in conjunction with elemental mapping to synthesize TiO2 nanoparticles in both anatase and rutile configurations, featuring surface modification through the application of geraniol (GER) in an optimized way.
Close-up imaging at high magnification unveiled densely packed nano-crystalline domains on the surface. In the case of the anatase form of TiO2 with GER, it exhibited a resemblance to unmodified TiO2 NPs and maintained a consistent size post-surface modification via GER.
To substantiate the existence of GER on the TiO2 NP surface, energy-dispersive X-ray spectroscopy (EDS) was employed for elemental mapping analysis. The distribution of elements on the TiO2 surface in both configurations indicated the presence of carbon, thereby validating the successful implementation of GER-driven modification. While both unmodified variants also displayed traces of carbon, the quantities were marginal. However, the synthesized TiO2 is efficient in terms of microbial activity.
Challenges
Modern instruments have revolutionized materials analysis by enabling simultaneous particle examination and elemental mapping, supplying an exhaustive comprehension of sample attributes. Techniques like scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) and transmission electron microscopy-electron energy loss spectroscopy (TEM-EELS) have emerged as essential tools for researchers.
However, certain challenges still exist that hinder the rapid commercialization of these processes. The need for higher nanoscale image resolution and high-processing data analysis techniques need to be optimized for elemental mapping. Modern-day advancements in Artificial Intelligence and industrial techniques are expected to help in this regard.
In short, both of these techniques have played a vital role in materials science for decades. The evolution of spectroscopy and the application of multidimensional data analysis through machine learning tools to study diverse particle types will prove fruitful in the future.
More from AZoM: Why is the Particle Analysis of Different Metal Powders Important?
References and Further Reading
Davison, C. et al. (2023). Expanding the boundaries of atomic spectroscopy at the single-cell level: critical review of SP-ICP-MS, LIBS and LA-ICP-MS advances for the elemental analysis of tissues and single cells. Anal Bioanal Chem. Available at: https://doi.org/10.1007/s00216-023-04721-8
Rausch, J. et. al. (2022). Automated identification and quantification of tire wear particles (TWP) in airborne dust: SEM/EDX single particle analysis coupled to a machine learning classifier. Science of The Total Environment, 803, 149832. Available at: https://doi.org/10.1016/j.scitotenv.2021.149832
Younis, A.B., Milosavljevic, V., Fialova, T. et al. (2023). Synthesis and characterization of TiO2 nanoparticles combined with geraniol and their synergistic antibacterial activity. BMC Microbiol 23, 207. Available at: https://doi.org/10.1186/s12866-023-02955-1
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