Page 20 - ILLS Annual Report 2018

BIOLOGY AND HEALTH
Lourdes Marcano. Spanish
Universidad del País Vasco (UPV/EHU), Spain
AUTHORS
I. Orue, L. Marcano, A. García-Prieto, A. García Arribas, A. Muela
and M.L. Fdez-Gubieda (University of País Vasco, Leioa, Spain)
P. Bender (University of Luxembourg, Luxembourg)
S. Valencia and M.A. Mawass (Helmholtz-Zentrum Berlin, Germany)
L. Fernández Barquín (CITIMAC, University of Cantabria, Santander, Spain) D. Gil-Cartón (CIC bioGUNE, CIBERehd, Derio, Spain)
D. Alba Venero (ISIS, Didcot, UK) D. Honecker (ILL)
ARTICLE FROM
Nanoscale (2018)—doi: 10.1039/c7nr08493e
REFERENCES
[1] R. Blakemore, Science 190 (1975) 377
[2] A. Muela et al., J. Phys. Chem. C 120 (2016) 24437 [3] S.R. Mishra et al., Nanoscale 8 (2016) 1309
[4] D. Honecker et al., Eur. Phys. J. B 76 (2010) 209
Magnetospirillum gryphiswaldense is an aquatic micro- organism able to biomineralise high-quality magnetite nanoparticles called magnetosomes. The bacteria contain
a variable number of 45 nm-sized cuboctahedral magnetite magnetosomes arranged in a chain [1]. Since magnetosomes are single magnetic domains, the chain behaves like a large, permanent magnetic dipole able to orient all the bacteria along Earth’s magnetic field in order to swim towards the riverbeds they inhabit.
c)
‘Small-angle neutron scattering is a useful method for understanding the underlying mechanisms of complex natural structures such as magnetosome chains.’
On the magnetosome chain configuration: a natural magnetic nanostructure
Small-angle neutron scattering diffractometer D33
The potential use of magnetotactic bacteria as biorobots makes comprehension of the magnetosome chain configuration an issue of paramount importance. Rather than the a priori expected straight lines, magnetosome chains present a helical-shaped structure. This configuration has been investigated by polarised small-angle neutron scattering. Our experimental and theoretical results suggest a mechanism of chain formation arising from competition between the dipolar interaction of magnetosomes
within the chain and the forces exerted on each particle by the cytoskeleton.
a)
105
104
103
102
101
100
10-1
P(r) (a.u.)
I (cm-1)
Figure 1
a) Field-dependence of the nuclear scattering intensities Inuc(q) and cross-terms Icross(q) at 2mT and 1T, respectively.
b) Pair-distance distribution function P(r) obtained by indirect Fourier transform of the 1D scattering intensities in (a).
c) Schematic representation of the two-step magnetisation process. ANNUAL REPORT 2018
00
75 100
125 150
175 200
b)
SAXS
sphere
25 50
10-2
0.5
SANS:
nuclear: 2 mT nuclear: 1 T cross-term: 2 mT cross-term: 1 T
H =0
H = 2mT
H = 1T
0.03
0.1
q (nm-1)
r (nm)