Quantum Dots in an Amphiphilic Polyethyleneimine Derivative Platform for Cellular Labeling, Targeting, Gene Delivery, and Ratiometric Oxygen Sensing

Abstract

Amphiphilic polyethyleneimine derivatives (amPEIs) were synthesized and used to encapsulate dozens of quantum dots (QDs). The QD-amPEI composite was ∼100 nm in hydrodynamic diameter and had the slightly positive outer surface that suited well for cellular internalization. The QD-amPEI showed very efficient QD cellular labeling with the labeled cell fluorescence intensity more than 10 times higher than conventional techniques such as Lipofectamine-assisted QD delivery. QD-amPEI was optimal for maximal intracellular QD delivery by the large QD payload and the rapid endocytosis kinetics. QD-amPEI platform technology was demonstrated for gene delivery, cell-specific labeling, and ratiometric oxygen sensing. Our QD-amPEI platform has two partitions: positive outer surface and hydrophobic inside pocket. The outer positive surface was further exploited for gene delivery and targeting. Co-delivery of QDs and GFP silencing RNAs was successfully demonstrated by assembling siRNAs to the outer surfaces, which showed the transfection efficiency an order of magnitude higher than conventional gene transfections. Hyaluronic acids were tethered onto the QD-amPEI for cell-specific targeted labeling which showed the specific-to-nonspecific signal ratio over 100. The inside hydrophobic compartment was further applied for cohosting oxygen sensing phosphorescence Ru dyes along with QDs. The QD-Ru-amPEI oxygen probe showed accurate and reversible oxygen sensing capability by the ratiometric photoluminescence signals, which was successfully applied to cellular and spheroid models.

Quantum dots–DNA bioconjugates: synthesis to applications

“…This DHLA-PEG hybrid layer has moderate cationic nature along with antifouling properties and can be used to quantitatively load DNA mediated by electrostatic interactions [65]. Other strategy involves using small molecule ligands such as MPA (negative charge) followed by PEI (polyethylenimine) [66][67][68]. These high to moderately cationic QDs have been extensively used to electrostatically assemble excess of DNA for biodetection and delivery of therapeutically active agents.…”

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

“…PEI is a cationic synthetic polymer with large numbers of amine groups and it has been used successfully in gene delivery system [34,35]. In particular, their branched structures are effective carriers of DNA sequences and plasmids [36].…”

Facile synthesis of wormlike quantum dots-encapsulated nanoparticles and their controlled surface functionalization for effective bioapplications

“…Such kinds of gene carriers are mostly fabricated via appropriate surface functionalization with cationic polymers [23][24][25][26][27] or small molecules [8,28]. Furthermore, cellular imaging might be simultaneously achieved in the same nanostructure owing to the optical properties of QDs [24][25][26]. QDs have been utilized to track the RNA delivery process.…”