1 research outputs found
Self-Assembled Polypeptide Nanogels with Enzymatically Transformable Surface as a Small Interfering RNA Delivery Platform
Nanometer-size
gel particles, or nanogels, have potential for delivering
therapeutic macromolecules. A cationic surface promotes cellular internalization
of nanogels, but undesired electrostatic interactions, such as with
blood components, cause instability and toxicities. Poly(ethylene
glycol) coating has been used to shield charges, but this decreases
delivery efficiency. Technical difficulties in synthesis and controlling
molecular weights make it unfeasible to, instead, coat with biodegradable
polymers. Our proposed solution is cationized nanogels enzymatically
functionalized with branched polysaccharide chains, forming a shell
to shield charges and increase stability. Biodegradation of the polysaccharides
by an endogenous enzyme would then expose the cationic charges, allowing
cellular internalization and cargo delivery. We tested this concept,
preparing maltopentaose functionalized cholesteryl poly(l-lysine) nanogel and using tandem enzymatic polymerization with glycogen
phosphorylase and glycogen branching enzyme, to add branched amylose
moieties, forming a CbAmyPL nanogel. We characterized CbAmyPL nanogels
and investigated their suitability as small interfering RNA (siRNA)
carriers in murine renal carcinoma (Renca) cells. The nanogels had
neutral ζ potential values that became positive after degradation
by α-amylase. Foster resonance energy transfer demonstrated
that the nanogels formed stable complexes with siRNA, even in the
presence of bovine serum albumin and after α-amylase exposure.
The nanogels, with or without α-amylase, were not cytotoxic.
Complexes of CbAmyPL with siRNA against vascular endothelial growth
factor (VEGF), when incubated alone with Renca cells decreased VEGF
mRNA levels by only 20%. With α-amylase added, however, VEGF
mRNA knockdown by the siRNA/nanogels complexes was 50%. Our findings
strongly supported the hypothesis that enzyme-responsive nanogels
are promising as a therapeutic siRNA delivery platform