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A Deep Look Into Erionite Fibres: an Electron Microscopy Investigation of their Self-Assembly.

Matassa R, Familiari G, Relucenti M, Battaglione E, Downing C, Pacella A, Cametti G, Ballirano P - Sci Rep (2015)

Bottom Line: The reasons for the observed morphological variability have been explained by considering the structural defects located at ED surface fibrils (bi-dimensional ribbons) and the presence of nontronite, an iron-bearing clay mineral embedding the ER fibrils (mono-dimensional rods).ER4G shows a decrease in width of the rod-like fibres due to their partial digestion by SLF leaching, which synchronously dissolves nontronite.The reported results represent a valuable background toward the full comprehension of the morphological mechanisms responsible for potentially damage of lung tissue through the potential relocation of fibers to extrapulmonary sites, increasing the carcinogenic risk to humans.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomical, Histological, Forensic and Orthopaedic Sciences, Section of Human Anatomy, Sapienza University of Rome, Via A. Borelli 50, 00161 Rome, Italy.

ABSTRACT
The exposure of humans to erionite fibres of appropriate morphology and dimension has been unambiguously linked to the occurrence of Malignant Mesothelioma. For this reason, a detailed morpho-structural investigation through Electron Microscopy techniques has been performed on erionite samples collected at two different localities, Durkee (ED) and Rome (ER), Oregon, USA. The sample from Rome has been also investigated after a prolonged leaching with Gamble's solution (ER4G) in order to evaluate the possible occurrence of morpho-structural modifications induced by this Simulated-Lung-Fluid (SLF). Here we report how the micrometric erionite fibres evolve in irregular ribbon- or rod-like bundles as a function of different nano-structural features. The reasons for the observed morphological variability have been explained by considering the structural defects located at ED surface fibrils (bi-dimensional ribbons) and the presence of nontronite, an iron-bearing clay mineral embedding the ER fibrils (mono-dimensional rods). ER4G shows a decrease in width of the rod-like fibres due to their partial digestion by SLF leaching, which synchronously dissolves nontronite. The reported results represent a valuable background toward the full comprehension of the morphological mechanisms responsible for potentially damage of lung tissue through the potential relocation of fibers to extrapulmonary sites, increasing the carcinogenic risk to humans.

No MeSH data available.


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Structural study of ER4G fibres.(a) BF TEM image of ER4G fibres. Bottom Inset shows a magnified area. (b) EDP taken from Fig. 4a showing a complex array of diffraction spots and Debye rings. (c) DF TEM image of Fig. 4a obtained by selecting the micrometric area of erionite (004) reflection, identified by the black circle in Fig. 4b. White arrows point to small nontronite particles.
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f4: Structural study of ER4G fibres.(a) BF TEM image of ER4G fibres. Bottom Inset shows a magnified area. (b) EDP taken from Fig. 4a showing a complex array of diffraction spots and Debye rings. (c) DF TEM image of Fig. 4a obtained by selecting the micrometric area of erionite (004) reflection, identified by the black circle in Fig. 4b. White arrows point to small nontronite particles.

Mentions: SLF leached erionite from Rome. The BF image of the ER4G sample (Fig. 4a) shows aggregates of smooth fibres, with diameters varying from 300 to 650 nm (See also in Supplementary Informations Fig. S1). Compared to the untreated ER sample, the diameter of the fibres is slightly smaller and the amount of nontronite flakes seems to be strongly reduced. Therefore, small fibres suffer from cleavage effects, testified by fractures and fraying of the brittle fibres observed in the magnified image (Inset). As previously indicated, EDX analysis of fibres indicated the absence of iron due to the removal of nontronite from their surface produced by the SLF leaching process. To identify the various mineral phases, EDP has been acquired, showing the rectangular array of diffraction spots, attributed to erionite, previously observed for the other samples (Fig. 4b). No diffraction contribution of nontronite was detected. To visualize the relative crystallographic orientation of fibres, a DF image has been acquired by placing the objective aperture around the (004) reflection of erionite. The image shows a few bright areas, indicating fully crystalline regions, of the fibres displayed in Fig. 4c. In particular, it is noteworthy that the termination of the single fibre, which has a width of ca. 300 nm, is crystalline, differently from the remaining area of the field of view, which is not bright. This result agrees with the partial amorphisation of the leached fibres reported by Ballirano and Cametti24 from XRPD data. Isolated nontronite flakes, reported in Supplementary Information (Fig. S4a), have been detected in other areas. Nontronite still evidences its polycrystalline behaviour as testified by the Debye rings, marked by red arcs, observed in SAED patterns (Fig. S4b). The corresponding DF image still shows a random distribution of small nontronite nanoparticle within the flake (Fig. S4c).


A Deep Look Into Erionite Fibres: an Electron Microscopy Investigation of their Self-Assembly.

Matassa R, Familiari G, Relucenti M, Battaglione E, Downing C, Pacella A, Cametti G, Ballirano P - Sci Rep (2015)

Structural study of ER4G fibres.(a) BF TEM image of ER4G fibres. Bottom Inset shows a magnified area. (b) EDP taken from Fig. 4a showing a complex array of diffraction spots and Debye rings. (c) DF TEM image of Fig. 4a obtained by selecting the micrometric area of erionite (004) reflection, identified by the black circle in Fig. 4b. White arrows point to small nontronite particles.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4645157&req=5

f4: Structural study of ER4G fibres.(a) BF TEM image of ER4G fibres. Bottom Inset shows a magnified area. (b) EDP taken from Fig. 4a showing a complex array of diffraction spots and Debye rings. (c) DF TEM image of Fig. 4a obtained by selecting the micrometric area of erionite (004) reflection, identified by the black circle in Fig. 4b. White arrows point to small nontronite particles.
Mentions: SLF leached erionite from Rome. The BF image of the ER4G sample (Fig. 4a) shows aggregates of smooth fibres, with diameters varying from 300 to 650 nm (See also in Supplementary Informations Fig. S1). Compared to the untreated ER sample, the diameter of the fibres is slightly smaller and the amount of nontronite flakes seems to be strongly reduced. Therefore, small fibres suffer from cleavage effects, testified by fractures and fraying of the brittle fibres observed in the magnified image (Inset). As previously indicated, EDX analysis of fibres indicated the absence of iron due to the removal of nontronite from their surface produced by the SLF leaching process. To identify the various mineral phases, EDP has been acquired, showing the rectangular array of diffraction spots, attributed to erionite, previously observed for the other samples (Fig. 4b). No diffraction contribution of nontronite was detected. To visualize the relative crystallographic orientation of fibres, a DF image has been acquired by placing the objective aperture around the (004) reflection of erionite. The image shows a few bright areas, indicating fully crystalline regions, of the fibres displayed in Fig. 4c. In particular, it is noteworthy that the termination of the single fibre, which has a width of ca. 300 nm, is crystalline, differently from the remaining area of the field of view, which is not bright. This result agrees with the partial amorphisation of the leached fibres reported by Ballirano and Cametti24 from XRPD data. Isolated nontronite flakes, reported in Supplementary Information (Fig. S4a), have been detected in other areas. Nontronite still evidences its polycrystalline behaviour as testified by the Debye rings, marked by red arcs, observed in SAED patterns (Fig. S4b). The corresponding DF image still shows a random distribution of small nontronite nanoparticle within the flake (Fig. S4c).

Bottom Line: The reasons for the observed morphological variability have been explained by considering the structural defects located at ED surface fibrils (bi-dimensional ribbons) and the presence of nontronite, an iron-bearing clay mineral embedding the ER fibrils (mono-dimensional rods).ER4G shows a decrease in width of the rod-like fibres due to their partial digestion by SLF leaching, which synchronously dissolves nontronite.The reported results represent a valuable background toward the full comprehension of the morphological mechanisms responsible for potentially damage of lung tissue through the potential relocation of fibers to extrapulmonary sites, increasing the carcinogenic risk to humans.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomical, Histological, Forensic and Orthopaedic Sciences, Section of Human Anatomy, Sapienza University of Rome, Via A. Borelli 50, 00161 Rome, Italy.

ABSTRACT
The exposure of humans to erionite fibres of appropriate morphology and dimension has been unambiguously linked to the occurrence of Malignant Mesothelioma. For this reason, a detailed morpho-structural investigation through Electron Microscopy techniques has been performed on erionite samples collected at two different localities, Durkee (ED) and Rome (ER), Oregon, USA. The sample from Rome has been also investigated after a prolonged leaching with Gamble's solution (ER4G) in order to evaluate the possible occurrence of morpho-structural modifications induced by this Simulated-Lung-Fluid (SLF). Here we report how the micrometric erionite fibres evolve in irregular ribbon- or rod-like bundles as a function of different nano-structural features. The reasons for the observed morphological variability have been explained by considering the structural defects located at ED surface fibrils (bi-dimensional ribbons) and the presence of nontronite, an iron-bearing clay mineral embedding the ER fibrils (mono-dimensional rods). ER4G shows a decrease in width of the rod-like fibres due to their partial digestion by SLF leaching, which synchronously dissolves nontronite. The reported results represent a valuable background toward the full comprehension of the morphological mechanisms responsible for potentially damage of lung tissue through the potential relocation of fibers to extrapulmonary sites, increasing the carcinogenic risk to humans.

No MeSH data available.


Related in: MedlinePlus