From celebration to contamination: Analysing microplastics released by burst balloons

Air balloons are a ubiquitous presence in our daily lives, and their rupture may release a substantial quantity of debris, as investigated herein. We employ Raman imaging to capture the fragments resulting from balloon explosions, enabling the identification and direct visualisation of minute microplastic particles / fragments with an improved signal-to-noise ratio for precise quantification. To circumvent the generation of misleading confocal Raman images, we recommend employing terrain mapping to scan the three-dimensional surface of the sample. It is important to acknowledge that the analysis of microplastics at the micro-scale inherently poses limitations in terms of throughput, as it necessitates a trade-off between low and high magnifications. We conduct explosive experiments on ten-to-hundred balloons, collecting debris from various angles and positions. Our investigation involves the random testing of multiple samples / sample positions at the micro-scale, with subsequent extrapolation to estimate the total amount of microplastics. The amalgamation of these results through statistical analysis indicates that each balloon explosion can potentially release tens-to-thousands of microplastics, highlighting a concern that has hitherto received insufficient attention. The characterisation approach, particularly the random Raman scanning method in combination with SEM and the statistical analysis on accumulated samples employed in this report, has the potential to serve as a useful tool in future research on microplastics and even nanoplastics.

Raman imaging to identify microplastics released from toothbrushes: algorithms and particle analysis

Microplastics are small plastic fragments that are of increasing concern due to their potential impacts on the environment and human health. The source of microplastics is not completely clear and might originate in daily lives such as from toothbrushes. When toothbrushes are used to clean teeth, small plastic debris and fragments can be potentially released into mouths directly or environment indirectly. This study aims to examine the release of microplastics from toothbrushes, using Raman imaging to identify and visualise the plastic debris with an increased signal-noise ratio via hyper-spectrum analysis. Using algorithms to convert the hyper-spectrum to an image, the plastic can be distinguished from the co-formulated titanium oxide particles that are not uniformly distributed along the plastics. The non-uniform distribution can lead to the bias results if a single spectrum analysis is conducted at one position rather than imaging analysis to scan an area. The potential false image originating from the off-focal position for the confocal Raman is overcome using the terrain map to guide the Raman imaging. The imaging analysis balancing between the low magnification to capture the overview and the high magnification to test the details is also discussed. While the release amount of microplastics from the toothbrush is estimated at thousands daily with the expected variation, the results of this study have confirmed the release of microplastics in daily lives. The imaging analysis approach along with algorithm can help to identify the chemical elements of microplastics from the complex background, which can benefit the further research on microplastics towards risk assessment and remediation.

Geochemical and morphological characterization of particles originating from tunnel construction

Rock particles from drilling and blasting during tunnel construction (DB particles) are released to the aquatic environment where they may cause negative toxicological and ecological effects. However, there exists little research on the difference in morphology and structure of these particles. Despite this DB particles are assumed to be sharper and more angular than naturally eroded particles (NE particles), and in consequence cause greater mechanical abrasion to biota. Moreover, morphology of DB particles is assumed to depend on geology, thus depending on where construction takes place different morphologies may be emitted. The objectives in the current study were to investigate the morphological differences between DB and NE particles, and the influence of mineral and elemental content on DB particles. Particle geochemistry and morphology were characterized by inductively coupled plasma mass spectrometry, micro-X-ray fluorescence, X-ray diffraction, environmental scanning electron microscope interfaced with energy dispersive X-ray, stereo microscope, dynamic image analysis and coulter counter. DB particles (61-91% < 63 μm) collected from five different tunnel construction locations in Norway were 8-15% more elongated (lower aspect ratio) than NE particles from river water and sediments, although their angularity was similar (solidity; diff 0.3-0.8%). Despite distinct mineral and elemental characteristics between tunnel construction locations, DB morphology was not explained by geochemical content since only 2-2.1% of the variance was explained. This suggests that particle formation mechanisms during drilling and blasting are more influential of morphology than mineralogy, when working in granite-gneiss terrain. When tunnelling in granite-gneiss terrain, particles with greater elongation than natural particles may enter aquatic systems.

A workflow for low-cost automated image analysis of myxomycete spore numbers, size and shape

Measuring spore size is a standard method for the description of fungal taxa, but in manual microscopic analyses the number of spores that can be measured and information on their morphological traits are typically limited. To overcome this weakness we present a method to analyze the size and shape of large numbers of spherical bodies, such as spores or pollen, by using inexpensive equipment. A spore suspension mounted on a slide is treated with a low-cost, high-vibration device to distribute spores uniformly in a single layer without overlap. Subsequently, 10,000 to 50,000 objects per slide are measured by automated image analysis. The workflow involves (1) slide preparation, (2) automated image acquisition by light microscopy, (3) filtering to separate high-density clusters, (4) image segmentation by applying a machine learning software, Waikato Environment for Knowledge Analysis (WEKA), and (5) statistical evaluation of the results. The technique produced consistent results and compared favorably with manual measurements in terms of precision. Moreover, measuring spore size distribution yields information not obtained by manual microscopic analyses, as shown for the myxomycete Physarum albescens. The exact size distribution of spores revealed irregularities in spore formation resulting from the influence of environmental conditions on spore maturation. A comparison of the spore size distribution within and between sporocarp colonies showed large environmental and likely genetic variation. In addition, the comparison identified specimens with spores roughly twice the normal size. The successful implementation of the presented method for analyzing myxomycete spores also suggests potential for other applications.

Nano-Microscopy of Therapeutic Antibody Aggregates in Solution

Scanning electron-assisted dielectric microscopy (SE-ADM) is a new microscope technology developed to observe the fine structure of biological samples in aqueous solution. One main advantage of SE-ADM is that it does not require sample pretreatment, including dehydration, drying, and staining, which is indispensable in conventional scanning electron microscopy (SEM) and can cause sample deformation. In addition, the sample is not directly irradiated with an electron beam in SE-ADM, further avoiding damage. The resolution of SE-ADM is higher than that of an optical microscope, which is typically used for observing biological samples in a solution, allowing for the observation of the detailed structure of samples. Considering these advantages, we applied SE-ADM to observe aggregates of therapeutic immunoglobulin G (IgG) of various sizes and shapes in an aqueous solution. In this chapter, we outline the step-by-step procedure for observing aggregates of monoclonal antibodies using SE-ADM and the subsequent analysis of the particle distribution and calculation of the fractal dimension using SE-ADM image data. The proposed method for particle analysis is highly reliable with respect to size measurement and can determine the diameter of a sample with an accuracy of ±20%, a precision of ±10%, and a lower limit of quantification of ≤50 nm. Further, by calculating the fractal dimension of the image, it is possible to classify the shape of the aggregates and determine the mechanism of aggregation.

Challenges for Cell-Based Medicinal Products From a Pharmaceutical Product Perspective

Advanced therapy medicinal products (ATMPs), such as somatic cell-therapy medicinal products or tissue-engineered products for human use, offer new and potentially curative opportunities to treat yet untreatable diseases or disorders. For cell-therapy medicinal products (CBMPs), multiple stability and quality challenges exist and relate to the cellular composition and unstable nature of these parenteral preparations. It is the aim of this review to discuss open questions and problems associated with the development, manufacturing and testing of CBMPs from a pharmaceutical drug product perspective. This includes safety, storage and handling, particulates, the choice of container closure systems and integrity. Analytical methods commonly used to evaluate the quality of the final CBMP to ensure patient's safety will be discussed. Particulate contamination in final products deserve special attention since CBMPs cannot be sterile filtered. Visible and sub-visible particles may represent environmental contaminations or may form during storage. They may be introduced from processing materials such as single use product contact materials, ancillary materials, or any components such as primary packaging used for the final product. Currently available analytical methods for detecting particulates may not be easily applicable to CBMPs due to their inherent particulate nature and appearance.

Quantitative Differentiation of Protein Aggregates From Other Subvisible Particles in Viscous Mixtures Through Holographic Characterization

We demonstrate the use of holographic video microscopy to detect individual subvisible particles dispersed in biopharmaceutical formulations and to differentiate them based on material characteristics measured from their holograms. The result of holographic analysis is a precise and accurate measurement of the concentrations and size distributions of multiple classes of subvisible contaminants dispersed in the same product simultaneously. We demonstrate this analytical technique through measurements on model systems consisting of human IgG aggregates in the presence of common contaminants such as silicone oil emulsion droplets and fatty acids. Holographic video microscopy also clearly identifies metal particles and air bubbles. Being able to differentiate and characterize the individual components of such heterogeneous dispersions provides a basis for tracking other factors that influence the stability of protein formulations including handling and degradation of surfactant and other excipients.

[Five million wear simulation and particle analysis of carbon-based nano-multilayer coatings titanium alloy femoral head]

Objective: To analyze the wear debris characteristics ofcarbon-based nano- multilayer coatings on Ti(6)Al(4)V alloys and compared with the cobalt chromium molybdenum alloy (CoCrMo) femoral head to evaluate the friction and wear performance of the new coated femoral head. Methods: Three groups were set up in the wear simulation experiment according to the type of femoral head. Group A: imported Cobalt-Chromium-Molybdenum alloy femoral head (CoCrMo); group B: Titanium alloy femoral head (Ti(6)Al(4)V) with carbon-based nano-multilayer coatings; group C: domestic Cobalt-Chromium-Molybdenum alloy femoral head (CoCrMo). All heads were jointed with an ultra-high molecular weight polyethylene (UHMWPE) acetabular cup. Serum samples were collected and stored in the hip joint simulator. After the sample has been digested and diluted, it was filtered through 5 μm, 1.2 μm and 0.4 μm filters, and the filter paper was collected for testing. Scanning electron microscope (SEM) was used to randomly select regions on the filter to obtain images of wear debris. Energy dispersive X-ray spectroscopy (EDS) was used to determine the elemental type of the particle and to eliminate possible contamination. The composition and structure of the abrasive chips were measured using Fourier transform infrared spectrometer (FTIR). The parameters related to the wear debris includingparticle size, shape, number and volume were calculated. The differences in correlation parameters between the groups were compared to evaluate the friction and wear properties of the new coated joints. Results: The main component of the wear debris produced was UHMWPE, and the particle size was mostly below 1 μm. The submicron particle ratio of group B was 49.4%, which was significantly lower than that of the group A and C (75% and 60%, respectively; χ(2)=66.032, 31.754, both P<0.017). The shape was mainly round, and there was no statistical difference between the groups (χ(2)=0.590, P=0.744). The number of particles in group B was significantly less than that of group C on all filters (t=9.960, 8.019, 5.790, all P<0.01), and less than group A on the 0.4 μm filter (t=7.810, P=0.000). Conclusion: The frictional wear performance of the new carbon-based nano-multilayer coatings femoral head is significantly better than that of the domestic femoral head, and even partially exceeds the imported femoral head level, which helps to reduce the production of particles and prevent osteolysis and aseptic loosening induced by UHMWPE particles.

Backside wear in acetabular hip joint replacement

INTRODUCTION

Besides head-insert articulation in hip joint replacements, micro-motions between the backside of assembled polyethylene acetabular liners and the metal cup may cause additional wear. Pelvic osteolysis frequently occurs in the region of screw holes, and cup loosening hints to clinically relevant amounts of polyethylene backside wear. It has yet to be confirmed whether backside wear particles differ in size and morphology compared to articulating wear. Previous methods have been limited to subjective assessment of backside surface damages without consideration of wear debris. The aim of this study was to develop and validate a method for quantitative in vitro measurements of polyethylene backside wear in artificial hip cups and to characterize these wear particles for the first time.

METHODS

Titanium cup-systems (Plasmafit®Plus7, Aesculap, UHMWPE liner) were sinusoidally loaded (2.5 kN) and a torque of 5 Nm was simultaneously applied. The front and rear side of the cup were separated to isolate backside wear. After 2 × 10⁶ cycles the surrounding fluid was filtered and a particle analysis was performed.

RESULTS

Backside wear had a particles size of 64.1 ± 1.9 nm and was verified as round and oval particles with partly rough outlines. An estimated total number of particles of 1.26 × 10⁹ ± 1.67 × 10⁸ per 10⁶ cycles was determined.

CONCLUSION

Backside wear was estimated to be several times lower than published values of articulating wear. However, polyethylene backside wear particles represented significantly smaller particles with partly roughened outlines than articulating wear particles and may therefore cause higher biological response in macrophage-mediated bone resorption compared to articulated particles.

STATEMENT OF SIGNIFICANCE

Within this study, an analytical method for quantitative measuring polyethylene backside wear of artificial hip cups was successfully developed and validated for the first time. It could be shown that backside wear is still present, even in modern cup-systems. These findings can be further used for investigations of the osteolytic potential of polyethylene particles, for evaluating and improving new implant systems and to evaluate the effectiveness of screw hole plugs to prevent the particle migration to the acetabulum.

Optical microscopy as a new approach for characterising dust particulates in urban environment

In urban environments airborne particulates (dust) must be managed to ensure that industry and community coexist in a mutually beneficial and sustainable manner. The composition of the dust is a function of the local environment and industry. In general, there is a view by many community members that a significant proportion of inhalable (PM₁₀) and respirable (PM_2.5) dust in these environments could be coal. Thus there is a need to have an analytical method that provides a quantitative analysis of the amount and size distribution of the different particulates that can be present in air samples. Australia's national research body, the Commonwealth Scientific and Industrial Research Organisation (CSIRO) has developed a Coal Grain Analysis (CGA) system that uses reflected light optical microscopy to provide a unique visual perspective, a qualitative feeling of the sample and quantitative information on the composition and size of the individual particles greater than 1 μm. Furthermore, semi-automated Optical Dust Marker software uses each individual particle's colour reflectance fingerprint to classify that particle. These markers can currently identify coal, combustion chars, iron, quartz/dark minerals, pyrite/bright materials and particulates of organic origin. This paper presents a case study performed using CGA to evaluate the dust composition and proportion of coal and other particulates and also their size distribution in samples collected in an urban area along a coal rail corridor in Newcastle (Australia). In coastal environments a significant proportion of dust can be water soluble (salt) particulates; the proportion of soluble particulates in those samples varied from 46% to 52.3%. The concentration of insoluble particles in samples varied from 5.9 to 15.5 μg m^-3 in the PM_2.5-10 fraction and from 0.4 to 0.9 μg m^-3 in the PM_1-2.5 fraction. All samples consisted predominantly of particles of organic origin (mostly plant and insect remains) - 55.3%-85.3% by mass. Dark material particles of mainly inorganic origin (low reflecting material, mainly stone dust, clay, soot, rubber and soil), combustion char and metal particles (rust and iron oxides) were present in lower concentrations - 0.0% to 19.9% by mass. The amount of coal in the water insoluble fraction of the samples ranged from 5.3% to 19.7% by mass with 2.9%-13.5% by mass of coal particles in the thoracic (2.5-10 μm) and 0.3%-1.2% by mass in the respirable (1-2.5 μm) size fraction.

Analytical and transfer characteristics of a fluorescent detection spray: Implications for subvisible and nanotrace particle transfers

Fluorescent detection sprays are applied to objects to elucidate evidence of contact. Billed as an invisible powder, evidence of contact between objects may be visualized through illumination by ultra-violet light, which causes the fluorescent tracer to luminesce. While the presence of the fluorescent powder on a suspect or object is often used as evidence of direct contact, the fine nature of the powder, which is comprised of sub-visible particles that are generally less than 10 μm in diameter, lends itself to higher-order transfers that do not necessarily involve the original object. Due to the small particle size and light-yellow color, the particles are generally invisible to the unaided eye in white light. This increases the opportunity for unwanted or unanticipated transfers (i.e., contamination). This article provides a microanalytical characterization of a common fluorescent tracer and the approaches by which this powder (or analogous powders) may be applied, detected, and specifically identified in quantities that range from major to trace. This research illustrates the ease of higher order cross-transfers (up to the 10th order) and the considerations necessary to maximize the evidentiary value of sub-visible particles and nanotraces, while minimizing the chances of cross-contamination.

Identification of possible sources of atmospheric PM10 using particle size, SEM-EDS and XRD analysis, Jharia Coalfield Dhanbad, India

Identification of responsible sources of pollution using physical parameter particulate matter (PM)10 in a critically polluted area is discussed in this paper. Database was generated by Ambient Air Quality Monitoring (AAQM) with respect to PM10 and PM2.5 in 18 monitoring stations at Jharia coalfield as per the siting criteria (IS: 5182, Part XIV) during 2011 to 2012. Identification of the probable sources of PM10 was carried out through particle size, shape, morphology analysis (scanning electron microscopy (SEM)), suitable compounds (X-ray diffraction (XRD)) and elements (energy-dispersive spectroscopy (EDS)). Monitoring stations nearby opencast mine were affected by the big-sized and irregular-shaped particles; on the other hand, monitoring stations nearby city were affected by the small-sized and regular-shaped particles. In a city area, additional sources like diesel generator (DG) set, construction activities, coal burning, etc., were identified. Blistering effects were also observed in the particles from mine fire-affected areas. Using the X-ray diffraction technique, presence of FeS2, CuO, FeSO4 and CuSO4 compounds was observed, which indicates the effects of mine fire on particulate emission due to presence of SO4(2-) and S2- ions.

Illustration and analysis of a coordinated approach to an effective forensic trace evidence capability

An effective trace evidence capability is defined as one that exploits all useful particle types, chooses appropriate technologies to do so, and directly integrates the findings with case-specific problems. Limitations of current approaches inhibit the attainment of an effective capability and it has been strongly argued that a new approach to trace evidence analysis is essential. A hypothetical case example is presented to illustrate and analyze how forensic particle analysis can be used as a powerful practical tool in forensic investigations. The specifics in this example, including the casework investigation, laboratory analyses, and close professional interactions, provide focal points for subsequent analysis of how this outcome can be achieved. This leads to the specification of five key elements that are deemed necessary and sufficient for effective forensic particle analysis: (1) a dynamic forensic analytical approach, (2) concise and efficient protocols addressing particle combinations, (3) multidisciplinary capabilities of analysis and interpretation, (4) readily accessible external specialist resources, and (5) information integration and communication. A coordinating role, absent in current approaches to trace evidence analysis, is essential to achieving these elements. However, the level of expertise required for the coordinating role is readily attainable. Some additional laboratory protocols are also essential. However, none of these has greater staffing requirements than those routinely met by existing forensic trace evidence practitioners. The major challenges that remain are organizational acceptance, planning and implementation.

Step-by-step quantitative analysis of focal adhesions

Focal adhesions (FAs) are specialized adhesive structures which serve as cellular communication units between cells and the surrounding extracellular matrix. FAs are involved in signal transduction and actin cytoskeleton organization. FAs mediate cell adhesion, which is a critical phenomenon in cancer research. Since cells can form many and micrometer scale FAs, their quantitative analysis demands well-optimized image analysis approaches [1–3]. Here, we have optimized the analysis of FAs of MDA-MB-231 breast cancer cells. The optimization is based on proper processing of immunofluorescence images of vinculin, which is one of the markers of FAs. All image processing steps are carried out using the ImageJ software, which is freely available and in the public domain. The advantages of our method are:•

The analysis steps are simplified by combining different plugins of the ImageJ program.

•

FAs are better detected with minimal false negatives due to optimized processing of fluorescent images.

•

This approach can be applied to quantify a variety of fluorescent images comprising focal and/or localized signals within a high background such as FAs, one of the many complex signaling structures in a cell.