Joonhyuck Park†, Junhwa Lee†, Jungheon Kwag‡, Yeonggyeong Baek‡, Bumju Kim§, Calvin Jinse Yoon⊥, Seoyeon Bok⊥, So-Hye Cho∥, Ki Hean Kim§⊥, G-One Ahn⊥, and Sungjee Kim*†‡
†Department of Chemistry, ‡School of Interdisciplinary Bioscience and Bioengineering, §Department of Mechanical Engineering, and ⊥Division of Integrative Biosciences and Biotechnology, Pohang University of Science & Technology (POSTECH), San 31, Hyoja-Dong, Nam-Gu, Pohang, Gyeong-Buk 790-784, South Korea
∥ Materials Architecturing Research Center, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791, South Korea
*Correspondence to Sungjee Kim
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.
Keywords: quantum dot; polyethyleneimine; cellular labeling; targeting; gene delivery; oxygen probe; amphiphilic encapsulation