2 research outputs found
Dually Gated Polymersomes for Gene Delivery
An
ideal gene carrier requires an excellent gating system to efficiently
load, protect, deliver, and release environmentally sensitive nucleic
acids on demand. Presented in this communication is a polymersome
with a “boarding gate” and a “debarkation gate”
in the membrane to complete the above important missions. This dually
gated polymersome is self-assembled from a block copolymer, polyÂ(ethylene
oxide)-<i>block</i>-polyÂ[<i>N</i>-isopropylacrylamide-<i>stat</i>-7-(2-methacryloyloxyethoxy)-4-methylcoumarin-<i>stat</i>-2-(diethylamino)Âethyl methacrylate] [PEO-<i>b</i>-PÂ(NIPAM-<i>stat</i>-CMA-<i>stat</i>-DEA)]. The
hydrophilic PEO chains form the coronas of the polymersome, whereas
the temperature and pH-sensitive PÂ(NIPAM-<i>stat</i>-CMA-<i>stat</i>-DEA) block forms the dually gated heterogeneous membrane.
The temperature-controlled “boarding gate” can be opened
at room temperature for facile encapsulation of siRNA and plasmid
DNA into polymersomes directly in aqueous solution. The “debarkation
gate” can be triggered by proton sponge effect for intracellular
release. Biological studies confirmed the successful encapsulation
of siRNA and plasmid DNA, efficient in vitro and in vivo gene transfection,
and the expression of green fluorescent protein (GFP) from GFP-encoding
plasmid, suggesting that this kind of polymersome with a dual gating
system can serve as an excellent biomacromolecular shuttle for gene
delivery and other biological applications
Synthesis and Mechanism Insight of a Peptide-Grafted Hyperbranched Polymer Nanosheet with Weak Positive Charges but Excellent Intrinsically Antibacterial Efficacy
Antimicrobial resistance
is an increasingly problematic issue in
the world and there is a present and urgent need to develop new antimicrobial
therapies without drug resistance. Antibacterial polymers are less
susceptible to drug resistance but they are prone to inducing serious
side effects due to high positive charge. Herein we report a peptide-grafted
hyperbranched polymer which can self-assemble into unusual nanosheets
with highly effective intrinsically antibacterial activity but weak
positive charges (+ 6.1 mV). The hyperbranched polymer was synthesized
by sequential Michael addition-based thiol–ene and free radical
mediated thiol–ene reactions, and followed by ring-opening
polymerization of <i>N</i>-carboxyanhydrides (NCAs). The
nanosheet structure was confirmed by transmission electron microscopy
(TEM) and atomic force microscopy (AFM) studies. Furthermore, a novel
“wrapping and penetrating” antibacterial mechanism of
the nanosheets was revealed by TEM and it is the key to significantly
decrease the positive charges but have a very low minimum inhibitory
concentration (MIC) of 16 μg mL<sup>–1</sup> against
typical Gram-positive and Gram-negative bacteria. Overall, our synthetic
strategy demonstrates a new insight for synthesizing antibacterial
nanomaterials with weak positive charges. Moreover, the unique antibacterial
mechanism of our nanosheets may be extended for designing next-generation
antibacterial agents without drug resistance