Adsorption of bovine serum albumin onto synthetic Fe-doped geomimetic chrysotile

Our plain-English summary of Adsorption of bovine serum albumin onto synthetic Fe-doped geomimetic chrysotile, by A. Adamiano, I.G. Lesci, D. Fabbri, et al (Journal of the Royal Society, Interface, 2015).

The study

• Authors: A. Adamiano, I.G. Lesci, D. Fabbri, N. Roveri
• Journal: Journal of the Royal Society, Interface
• Published: 2015;12(107)
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Synthetic stoichiometric and Fe-doped geomimetic chrysotile nanocrystals represent a reference standard to investigate the health hazard associated with mineral asbestos fibres. Experimental evidence suggests that the generation of reactive oxygen species and other radicals, catalysed by iron ions at the fibre surface, plays an important role in asbestos-induced cytotoxicity and genotoxicity. In this study, structural modification of bovine serum albumin (BSA) adsorbed onto synthetic chrysotile doped with different amounts of Fe has been investigated by Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TGA) and analytical pyrolysis coupled with gas chromatography-mass spectrometry. FT-IR data evidenced a marked increase in disordered structures like random coil and β-turn of BSA-nanocrystal adduct with 0.52 wt% of Fe doped. The TGA profile of the BSA revealed that its interaction with the synthetic chrysotile surface was strongly affected by the substitution of Fe into the chrysotile structure. The 2,5-diketopiperazine yields, formed upon thermal degradation of the polypeptide chain (pyrolysis-gas chromatography), changed when the BSA was adsorbed on the nanofibres. In general, results suggested that minute amount (less than 1 wt%) of Fe doping in chrysotile affected the protein-nanofibre interactions, supporting the role that this element may play in asbestos toxicity. The catalytic role of iron and the consequent unfolding of protein due to the structural surface modification of nanofibres were also evaluated.

© 2015 The Author(s) Published by the Royal Society. All rights reserved.

In plain English

This was a laboratory experiment, not a study of people or animals. The authors made synthetic chrysotile nanofibres in the laboratory. Some had no iron, and others had iron added at 0.52 or 1.78 percent by weight, amounts chosen to simulate the iron found in natural chrysotile. They mixed the fibres with bovine serum albumin (BSA), a blood protein from cattle. They then measured how much protein stuck to the fibres and how the protein's structure changed. Less protein was adsorbed as iron content rose. By UV measurement the amounts were 10.06, 9.46 and 8.15 percent by weight for 0, 0.52 and 1.78 percent iron, differences the authors reported as statistically significant. Infrared analysis showed the protein's beta-sheet content fell from 44 percent in untreated BSA to 11, 7 and 4 percent on the three fibre types. The largest increase in disordered structure was at 0.52 percent iron. Heating tests suggested a stronger protein-fibre interaction at higher iron content. The authors concluded that iron's role is more complex than previously suggested. They noted that the results cannot be directly extended to asbestos toxicity.

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 (in vitro) experiment: a protein was adsorbed onto synthetic chrysotile nanofibres and analysed by infrared spectroscopy, thermal gravimetric analysis and pyrolysis with gas chromatography-mass spectrometry
• Who was studied: No human or animal subjects. Samples of bovine serum albumin (BSA) were mixed with synthetic chrysotile nanofibres (40 mg of fibre with 10 ml of protein solution), prepared at the Department of Chemistry, University of Bologna, Italy
• Exposure: Synthetic stoichiometric (iron-free) chrysotile and synthetic chrysotile doped with iron at 0.52 and 1.78 wt%. The iron amounts were chosen to simulate the iron found in natural chrysotile
• Main results:
  • The amount of BSA adsorbed decreased as iron content rose. By UV spectroscopy it was 10.06 wt% for 0 wt% Fe, 9.46 wt% for 0.52 wt% Fe and 8.15 wt% for 1.78 wt% Fe. By thermal gravimetric analysis it was 10.38 wt%, 9.58 wt% and 8.49 wt% for the same three fibres.
  • The adsorption experiments were done in triplicate, and the authors reported the differences in adsorbed amount as statistically significant (p less than 0.05, two-tailed t-test).
  • Beta-sheet structure in BSA fell from 44% in native BSA to 11% on undoped chrysotile, 7% on 0.52 wt% Fe chrysotile and 4% on 1.78 wt% Fe chrysotile.
  • Beta-turn content rose from 15% in native BSA to 48% after adsorption onto undoped nanofibres, and to 58% on the 0.52% Fe-doped nanofibres. The increase in disordered structure was largest for the 0.52% Fe adducts.
  • The temperature at which the adsorbed protein degraded rose with iron content: about 304, 308 and 313 degrees C for 0, 0.52 and 1.78% Fe. The authors read this as a larger protein alteration with more iron.
  • In pyrolysis, the yield of cyclo(Pro-Leu), the most abundant diketopiperazine, was lower when BSA was adsorbed onto undoped chrysotile and lower still on doped nanofibres.
  • Pyrolysis products from protein side chains were produced in higher yields from adsorbed BSA than from BSA alone. The higher yields were often seen with chrysotile doped at 0.52 wt% Fe.
• The authors' conclusion: The authors concluded that iron's role in the asbestos-BSA interaction is more complex than previously suggested. They found an inverse relationship between fibre iron content and the amount of protein adsorbed, but a stronger interaction at higher iron content. They proposed two modes of interaction: a greater protein-unfolding effect at 0.52 wt% iron, and a stronger electrostatic effect at higher iron.
• Limitations the authors state:
  • The authors stated that the results cannot be directly extended to interpreting asbestos toxicity due to metal contamination.
  • Because the amounts of the BSA-fibre samples were small, measurement precision was estimated only from triplicate analysis of pure BSA (relative standard deviations 3 to 47%, average 11%). This precision was assumed to apply to the adsorbed BSA.
  • The authors noted that clear trends were not apparent in the pyrolysis product yields.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Chrysotile.

Medical terms in this study, explained in our Lexicon: Chrysotile, Reactive Oxygen Species (ROS), Genotoxicity, Infrared Spectroscopy (IR).

Related studies

• Interaction of bovine serum albumin with chrysotile: spectroscopic and morphological studies — G. Falini, E. Foresti, et al. (2006)
• Synthetic chrysotile nanocrystals as a reference standard to investigate surface-induced serum albumin structural modifications — P. Sabatino, L. Casella, et al. (2007)
• Adsorption of human serum albumin on the chrysotile surface: a molecular dynamics and spectroscopic investigation — R. Artali, A. Del Pra, et al. (2008)
• Adsorption isotherms of albumin and ferritin on Rhodesian chrysotile: effects of magnesium depletion — F. Valerio, M. Veggi, et al. (1980)
• Asbestos health hazard: a spectroscopic study of synthetic geoinspired Fe-doped chrysotile — E. Foresti, E. Fornero, et al. (2009)
• Iron-loaded synthetic chrysotile: a new model solid for studying the role of iron in asbestos toxicity — E. Gazzano, F. Turci, et al. (2007)

Browse return to medical research.