Biomedical Engineering Reference
In-Depth Information
structural studies. Thus, the principal observation is that binding leads to relatively
complete surface coverage for even low plasma concentrations. The protein con-
centration studies suggest a progressive displacement of proteins with lower affinity
in favor of those with higher. However, there are significant differences compared
to the more usual forms of adsorption: the protein layer is irreversible on the time
scales of the experiments. They have interpreted this to mean that the system seeks
to lower its surface energy by selecting and exchanging on shorter time scales from
the whole set of proteins that diffuse to the surface.
The transfer of nanoparticles from one biological environment to another such as
cellular uptake from blood stream or transport from cytosol to nucleus changes the
exchange rate and corona composition [
7
]. One study on the protein corona
evolution by transfer from blood plasma to the cytosolic fluid, a process similar
to cellular uptake of nanoparticles, showed that a fingerprint of previous environ-
ment will be left inside the corona which can be employed for monitoring the
transfer pathways of nanoparticles and their fate [
11
].
2.5
Ignored Issues of Protein Corona
Recent findings proved the fact that there are few additional ignored factors that
strongly affect the composition of protein corona and their consequence cellular
responses.
2.5.1 Temperature
One of the not investigated but very important influencing factors on the composi-
tion of protein corona is the slight changes in incubation temperature of
nanoparticles. As the mean body temperature for different individuals is in the
range from 35.8 to 37.2
C[
30
], this ignored factor is very important for the in vivo
applications of nanoparticle. It is noteworthy to mention that the temperature varies
for different parts of the body and the body temperature of females is slightly higher
than men and can be also influenced by their hormonal cycle (basal body tempera-
ture). During sleep, the body temperature decreases and manual work leads to an
increase of up to 2
C. This means that the body temperature for healthy humans
varies in the range from 35 to 39
C and can find a maximum of 41
C in the case of
fever [
31
]. If the corona formation is influenced by the temperature, then an
influence of the body temperature on the cellular uptake of nanoparticles can
appear.
Incubation of dextran-coated SPIONs (i.e., Fe
3
O
4
) with various surface
chemistries (e.g., negative, plain, and positive) with FBS, respectively, revealed
the fact that slight temperature changes can significantly vary the composition of
protein corona (see Fig.
2.5
)[
32
].
