la7b03126_si_001.pdf (1.52 MB)
Shape-Dependent Dissolution and Cellular Uptake of Silver Nanoparticles
journal contribution
posted on 2017-12-22, 00:00 authored by Christina Graf, Daniel Nordmeyer, Christina Sengstock, Sebastian Ahlberg, Jörg Diendorf, Jörg Raabe, Matthias Epple, Manfred Köller, Jürgen Lademann, Annika Vogt, Fiorenza Rancan, Eckart RühlThe cellular uptake
and dissolution of trigonal silver nanoprisms
(edge length 42 ± 15 nm, thickness 8 ± 1 nm) and mostly
spherical silver nanoparticles (diameter 70 ± 25 nm) in human
mesenchymal stem cells (hMSC’s) and human keratinocytes (HaCaT
cells) were investigated. Both particles are stabilized by polyvinylpyrrolidone
(PVP), with the prisms additionally stabilized by citrate. The nanoprisms
dissolved slightly in pure water but strongly in isotonic saline or
at pH 4, corresponding to the lowest limit for the pH during cellular
uptake. The tips of the prisms became rounded within minutes due to
their high surface energy. Afterward, the dissolution process slowed
down due to the presence of both PVP stabilizing Ag{100} sites and
citrate blocking Ag{111} sites. On the contrary, nanospheres, solely
stabilized by PVP, dissolved within 24 h. These results correlate
with the finding that particles in both cell types have lost >90%
of their volume within 24 h. hMSC’s took up significantly more
Ag from nanoprisms than from nanospheres, whereas HaCaT cells showed
no preference for one particle shape. This can be rationalized by
the large cellular interaction area of the plateletlike nanoprisms
and the bending stiffness of the cell membranes. hMSC’s have
a highly flexible cell membrane, resulting in an increased uptake
of plateletlike particles. HaCaT cells have a membrane with a 3 orders
of magnitude higher Young’s modulus than for hMSC. Hence, the
energy gain due to the larger interaction area of the nanoprisms is
compensated for by the higher energy needed for cell membrane deformation
compared to that for spheres, leading to no shape preference.