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Poly(trehalose): Sugar-Coated Nanocomplexes Promote Stabilization and Effective Polyplex-Mediated siRNA Delivery
journal contribution
posted on 2015-12-16, 23:41 authored by Antons Sizovs, Lian Xue, Zachary
P. Tolstyka, Nilesh P. Ingle, Yaoying Wu, Mallory Cortez, Theresa M. ReinekeWhen nanoparticles interact with
their environment, the nature
of that interaction is governed largely by the properties of its outermost
surface layer. Here, we exploit the exceptional properties of a common
disaccharide, trehalose, which is well-known for its unique biological
stabilization effects. To this end, we have developed a synthetic
procedure that readily affords a polymer of this disaccharide, poly(methacrylamidotrehalose)
or “poly(trehalose)” and diblock copolycations containing
this polymer with 51 repeat units chain extended with aminoethylmethacrylamide
(AEMA) at three degrees of polymerization (n = 34,
65, and 84). Two series of experiments were conducted to study these
diblock copolymers in detail and to compare their properties to two
control polymers [PEG-P(AEMA) and P(AEMA)]. First, we demonstrate
that the poly(trehalose) coating ensures colloidal stability of polyplexes
containing siRNA in the presence of high salt concentrations and serum
proteins. Poly(trehalose) retains the ability of trehalose to lower
the phase transition energy associated with water freezing and can
protect siRNA polyplexes during freeze-drying, allowing complete nanoparticle
resuspension without loss of biological function. Second, we show
that siRNA polyplexes coated with poly(trehalose) have exceptional
cellular internalization into glioblastoma cells that proceeds with
zero-order kinetics. Moreover, the amount of siRNA delivered by poly(trehalose)
block copolycations can be controlled by the siRNA concentration in
cell culture media. Using confocal microscopy we show that trehalose-coated
polyplexes undergo active trafficking in cytoplasm upon internalization
and significant siRNA-induced target gene down-regulation was achieved
with an IC50 of 19 nM. These findings coupled with a negligible
cytotoxicity suggests that poly(trehalose) has the potential to serve
as an important component of therapeutic nanoparticle formulations
of nucleic acids and has great promise to be extended as a new coating
for other nanobased technologies and macromolecules, in particular,
those related to nanomedicine applications.