title: Biodegradable MnO2Nanosheet-Mediated Signal Amplification in Living Cells Enables Sensitive Detection of Down-Regulated Intracellular MicroRNA.
abstract: The monitoring of intracellular microRNAs plays important roles in elucidating the biological function and biogenesis of miRNAs in living cells. However, because of their sequence similarity, low abundance, and small size, it is a great challenge to detect intracellular miRNAs, especially for those with much lower expression levels. To address this issue, we have developed an in cell signal amplification approach for monitoring down-regulated miRNAs in living cells based on biodegradable MnO2nanosheet-mediated and target-triggered assembly of hairpins. The MnO2nanosheets can adsorb and exhibit an excellent quenching effect to the dye labeled hairpin probes. Besides, due to their biodegradability, the MnO2nanosheets feature highly reduced cytotoxicity to the target cells. Upon entering cells, the surface-adsorbed FAM- and Tamra (TMR)-conjugated hairpins can be released due to the displacement reactions by other proteins or nucleic acids and the degradation of the MnO2nanosheets by cellular GSH. Subsequently, the down-regulated target miRNA-21 triggers cascaded assembly of the two hairpins into long dsDNA polymers, which brings the fluorescence resonance energy transfer (FRET) pair, FAM (donor), and TMR (acceptor) into close proximity to generate significantly enhanced FRET signals for detecting trace miRNA-21 in living cells. By carefully tailoring the sequences of the hairpins, the developed method can offer new opportunities for monitoring various trace intracellular miRNA targets with low expression levels in living cells.
authors.affiliation: Key Laboratory of Luminescent and Real-Time Analytical Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Southwest University , Chongqing 400715, P. R. China.
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.affiliation: Key Laboratory of Luminescent and Real-Time Analytical Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Southwest University , Chongqing 400715, P. R. China.
authors.forename: Daxiu
authors.initials: D
authors.lastname: Li
authors.affiliation: Key Laboratory of Luminescent and Real-Time Analytical Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Southwest University , Chongqing 400715, P. R. China.
authors.forename: Ruo
authors.identifier: http://orcid.org/0000-0003-3664-6236
authors.initials: R
authors.lastname: Yuan
authors.affiliation: Key Laboratory of Luminescent and Real-Time Analytical Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Southwest University , Chongqing 400715, P. R. China.
authors.forename: Yun
authors.identifier: http://orcid.org/0000-0003-2982-425X
authors.initials: Y
authors.lastname: Xiang
mesh_terms: D002470:Cell Survival; D004247:DNA; D015536:Down-Regulation; D031541:Fluorescence Resonance Energy Transfer; D017895:Manganese Compounds; D035683:MicroRNAs / Q000032:analysis*; D049329:Nanostructures; D010087:Oxides; D011108:Polymers
chemical_list: D017895:Manganese Compounds; D035683:MicroRNAs; D010087:Oxides; D011108:Polymers; D004247:DNA; C016552:manganese dioxide
keywords: living cells; manganese oxide nanosheets; microRNA; self-assembly; signal amplification