Amphiphilic Biodegradable PEG-PCL-PEI Triblock Copolymers for FRET-Capable in Vitro and in Vivo Delivery of siRNA and Quantum Dots

Abstract

Amphiphilic triblock copolymers represent a versatile delivery platform capable of co-delivery of nucleic acids, drugs, and/or dyes. Multifunctional cationic triblock copolymers based on poly(ethylene glycol), poly-ε-caprolactone, and polyethylene imine, designed for the delivery of siRNA, were evaluated in vitro and in vivo. Moreover, a nucleic acid-unpacking-sensitive imaging technique based on quantum dot-mediated fluorescence resonance energy transfer (QD-FRET) was established. Cell uptake in vitro was measured by flow cytometry, whereas transfection efficiencies of nanocarriers with different hydrophilic block lengths were determined in vitro and in vivo by quantitative real-time PCR. Furthermore, after the proof of concept was demonstrated by fluorescence spectroscopy/microscopy, a prototype FRET pair was established by co-loading QDs and fluorescently labeled siRNA. The hydrophobic copolymer mediated a 5-fold higher cellular uptake and good knockdown efficiency (61 ± 5% in vitro, 55 ± 18% in vivo) compared to its hydrophilic counterpart (13 ± 6% in vitro, 30 ± 17% in vivo), which exhibited poor performance. FRET was demonstrated by UV-induced emission of the acceptor dye. Upon complex dissociation, which was simulated by the addition of heparin, a dose-dependent decrease in FRET efficiency was observed. We believe that in vitro/in vivo correlation of the structure and function of polymeric nanocarriers as well as sensitive imaging functionality for mechanistic investigations are prerequisites for a more rational design of amphiphilic gene carriers.

Self-organization of an optomagnetic CoFe2O4–ZnS nanocomposite: preparation and characterization

“…Na2S was added drop-wise to zinc acetate under stirring at room temperature. Next, various synthesis temperatures (25,50,75, 100 °C) were applied and stirring was continued for 30 min.…”

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Fabrication of endothelial progenitor cell capture surface via DNA aptamer modifying dopamine/polyethyleneimine copolymer film

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Novel amphiphilic temperature responsive graft copolymers PCL-g-P(MEO2MA-co-OEGMA) via a combination of ROP and ATRP: synthesis, characterization, and sol-gel transition

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