ing tests on the Ni/spider-silk microbeams were performed. Mechanical testing of
a spider-silk microbridge was carried out using a nano indentation machine and
showed a UTS of 2.1 MPa. Magnetic membranes made of the Ni/silk ﬁlm can
be used for pumping or as valves in the microﬂuidic channels. Enhancement of
the mechanical properties of the Ni/spider-silk material could involve the use of
smaller particles, a sacriﬁcial etching process that does not use water and possible
processes that could rearrange the spider silk protein secondary structure during
the thin-ﬁlm formation step.
Our results allow us to come to several conclusions about the magnetic spider
silk. The concentration of Fe in the iron spider silk material obtained by using
the current method is low, resulting in low magnetization of the material. It has
previously been shown that the spheres have a higher concentration of Fe then the
rest of the ﬁlm. In addition, in areas where there appears to be a high concentration
of spider silk material, the formation of spheres is more inhibited.
Overall, this leads to the hypothesis that a lower concentration of spider silk
solution should form more densely packed particles with a higher concentration of
Fe. This is premised on the idea that when there is a higher concentration of spider
silk in the ﬁlm, the amino acids prefer to bind with themselves to form spider silk
ﬁlm. However, with less concentrated spider silk solution, the amino acids are
more likely to bind with iron to form spheres, because smaller amounts of spider
silk amino acids are available to form ﬁlms. Based on this hypothesis, 0.25% w/w
and 2% w/w regenerated spider silk solutions are mixed with iron pentacarbonyl
to form iron spider silk ﬁlms.
This work was supported by the Natural Science and Engineering Council
(NSERC) DISCOVERY grant and the Canada Foundation for Innovations (CFI)
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H., Preparation and characterization of polymer-coated magnetic nanoparticles. IEEE
Transactions on Magnetics, 37(4), 2660–2662 (2001).
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and characterization of polymer-coated iron nanoparticles, Chemistry of Materials, 14,
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