Tubular-shaped stoichiometric chrysotile nanocrystals

Our plain-English summary of Tubular-shaped stoichiometric chrysotile nanocrystals, by G. Falini, E. Foresti, M. Gazzano, et al (Chemistry, 2004).

The study

• Authors: G. Falini, E. Foresti, M. Gazzano, A.F. Gualtieri, M. Leoni, I.G. Lesci, N. Roveri
• Journal: Chemistry
• Published: 2004;10(12):3043-9
• Cited by: 33 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Stoichiometric chrysotile tubular nanocrystals have been synthesized as possible starting materials for applications toward nanotechnology, and as a standard reference sample for the investigation of the molecular interactions between chrysotile, the most utilized asbestos, and biological systems. Chrysotile nanocrystals have been synthesized under controlled hydrothermal conditions, and have been characterized by chemical, morphological, structural, spectroscopic and microcalorimetric analyses. They show a constant "cylinder-in-cylinder" morphology constituted by two or three concentric subunits. Each single nanocrystal has a tubular shape of about 49+/-1 nm in outer maximum diameter, and a hollow core of about 7+/-1 nm. Structural investigation carried out on an X-ray powder pattern allowed to improve the structural model proposed for chrysotile mineral samples. Synthetic chrysotile crystallizes in the monoclinic Cc space group with a=0.5340(1) nm, b=0.9241(1) nm, and c=1.4689(2) nm, beta=93.66(3) degrees.

In plain English

This laboratory chemistry study described a new way to make chrysotile asbestos synthetically. No people, animals or cells were studied. The authors reacted a laboratory-made silica (MCM41) with magnesium chloride in a strongly alkaline solution under heat and pressure (300 degrees C, 82 atm). X-ray, thermal, infrared and Raman tests indicated the product was pure clinochrysotile with no other mineral phases. Chemical analysis gave a silicon-to-magnesium ratio of 0.66, as expected for chrysotile, with very low amounts of foreign metals. Under the microscope, each nanocrystal was a hollow tube made of up to three nested tubes. The inner channel was about 7 nm across, crystals with three tubes were about 49 nm across, and each tube wall was about 7 nm thick. The tubes tended to clump into fibers. The X-ray data were used to refine the crystal structure model for chrysotile. The authors concluded that, because of its high purity, the synthetic chrysotile could serve as a possible standard reference sample for studying how chrysotile interacts with biological systems, and as a starting material for nanotechnology.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory synthesis and materials-characterization study (chemistry); not a health study
• Who was studied: Synthetic chrysotile nanocrystals made in the laboratory (University of Bologna and other Italian institutions). No people, animals or cells were studied.
• Exposure: No biological exposure. The material studied was synthetic chrysotile made by reacting MCM41 mesoporous silica with magnesium chloride (Si/Mg molar ratio 0.68) at pH 13.0, 300 degrees C and 82 atm, for 24 hours in the reported procedure
• Main results:
  • X-ray diffraction indicated the synthetic fibers were pure clinochrysotile
  • Chemical (ICP) analysis gave a Si/Mg molar ratio of 0.66, as expected for stoichiometric chrysotile, with very low amounts of foreign metals
  • Thermal analyses and infrared and Raman spectra showed none of the extra peaks or bands usually assigned to impurities in mineral chrysotile
  • The crystal structure was refined in the Cc space group, with unit cell a = 0.5340(1) nm, b = 0.9241(1) nm, c = 1.4689(2) nm (beta 93.66(3) degrees)
  • Each nanocrystal had a nested-tube ('cylinder-in-cylinder') shape made of up to three concentric tubes
  • The inner channel of the nanocrystals was about 7 nm in diameter
  • Nanocrystals made of three concentric tubes had an average outer diameter of about 49 nm (49 plus or minus 1 nm according to the abstract)
  • Each tube wall was a constant 7 nm thick, suggesting about ten octahedral-tetrahedral layers per tube
  • The nanocrystals tended to clump together to form fibers
• The authors' conclusion: The authors concluded that the absence of any poisoning with foreign ions, especially those considered responsible for asbestos toxicity, suggests the synthetic chrysotile could be used as a possible standard reference sample for studying mineral chrysotile's properties and interactions with biological systems. They also saw it as a possible starting material for nanotechnology
• Limitations the authors state:
  • The method used to fit the X-ray pattern (Rietveld) is not designed to account for the curved, cylindrical stacking of chrysotile layers

Topics

Medical terms in this study, explained in our Lexicon: Chrysotile, Monoclinic.

Related studies

• Different cellular responses evoked by natural and stoichiometric synthetic chrysotile asbestos — E. Gazzano, E. Foresti, et al. (2005)
• Synthetic chrysotile nanocrystals as a reference standard to investigate surface-induced serum albumin structural modifications — P. Sabatino, L. Casella, et al. (2007)
• Tubular crystals of chrysotile asbestos — T.F. Bates, L.B. Sand, et al. (1950)
• Chestnut bur-shaped aggregates of chrysotile particles enable inoculation of Escherichia coli cells with plasmid DNA — N. Yoshida, Y. Saeki (2004)
• Determination of low levels of free fibres of chrysotile in contaminated soils by X-ray diffraction and FTIR spectroscopy — E. Foresti, M. Gazzano, et al. (2003)
• Interaction of bovine serum albumin with chrysotile: spectroscopic and morphological studies — G. Falini, E. Foresti, et al. (2006)

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