Electrostatic Nucleic Acid Nanoassembly Enables Hybridization Chain Reaction in Living Cells for Ultrasensitive mRNA Imaging

• Published in: Journal of the American Chemical Society Vol. 137; no. 21; pp. 6829 - 6836
• Main Authors: Wu, Zhan, Liu, Gao-Qin, Yang, Xiao-Li, Jiang, Jian-Hui
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 03.06.2015
• Subjects: Animals; Cell Survival; Cells, Cultured; DNA - chemistry; DNA Probes - chemistry; Humans; Mice; Molecular Imaging; Nanostructures - chemistry; Nucleic Acid Hybridization; RNA, Messenger - analysis; Static Electricity
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/jacs.5b01778

Efficient approaches for intracellular delivery of nucleic acid reagents to achieve sensitive detection and regulation of gene and protein expressions are essential for chemistry and biology. We develop a novel electrostatic DNA nanoassembly that, for the first time, realizes hybridization chain reaction (HCR), a target-initiated alternating hybridization reaction between two hairpin probes, for signal amplification in living cells. The DNA nanoassembly has a designed structure with a core gold nanoparticle, a cationic peptide interlayer, and an electrostatically assembled outer layer of fluorophore-labeled hairpin DNA probes. It is shown to have high efficiency for cellular delivery of DNA probes via a unique endocytosis-independent mechanism that confers a significant advantage of overcoming endosomal entrapment. Moreover, electrostatic assembly of DNA probes enables target-initialized release of the probes from the nanoassembly via HCR. This intracellular HCR offers efficient signal amplification and enables ultrasensitive fluorescence activation imaging of mRNA expression with a picomolar detection limit. The results imply that the developed nanoassembly may provide an invaluable platform in low-abundance biomarker discovery and regulation for cell biology and theranostics.