title: A gold@polydopamine core-shell nanoprobe for long-term intracellular detection of microRNAs in differentiating stem cells.
abstract: The capability of monitoring the differentiation process in living stem cells is crucial to the understanding of stem cell biology and the practical application of stem-cell-based therapies, yet conventional methods for the analysis of biomarkers related to differentiation require a large number of cells as well as cell lysis. Such requirements lead to the unavoidable loss of cell sources and preclude real-time monitoring of cellular events. In this work, we report the detection of microRNAs (miRNAs) in living human mesenchymal stem cells (hMSCs) by using polydopamine-coated gold nanoparticles (Au@PDA NPs). The PDA shell facilitates the immobilization of fluorescently labeled hairpin DNA strands (hpDNAs) that can recognize specific miRNA targets. The gold core and PDA shell quench the fluorescence of the immobilized hpDNAs, and subsequent binding of the hpDNAs to the target miRNAs leads to their dissociation from Au@PDA NPs and the recovery of fluorescence signals. Remarkably, these Au@PDA-hpDNA nanoprobes can naturally enter stem cells, which are known for their poor transfection efficiency, without the aid of transfection agents. Upon cellular uptake of these nanoprobes, we observe intense and time-dependent fluorescence responses from two important osteogenic marker miRNAs, namely, miR-29b and miR-31, only in hMSCs undergoing osteogenic differentiation and living primary osteoblasts but not in undifferentiated hMSCs and 3T3 fibroblasts. Strikingly, our nanoprobes can afford long-term tracking of miRNAs (5 days) in the differentiating hMSCs without the need of continuously replenishing cell culture medium with fresh nanoprobes. Our results demonstrate the capability of our Au@PDA-hpDNA nanoprobes for monitoring the differentiation status of hMSCs (i.e., differentiating versus undifferentiated) via the detection of specific miRNAs in living stem cells. Our nanoprobes show great promise in the investigation of the long-term dynamics of stem cell differentiation, identification and isolation of specific cell types, and high-throughput drug screening.
authors.affiliation: †Department of Mechanical and Automation Engineering (Biomedical Engineering), ‡Department of Electronic Engineering (Biomedical Engineering), §School of Pharmacy, ∥Shun Hing Institute of Advanced Engineering, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
authors.forename: Chun Kit K
authors.initials: CK
authors.lastname: Choi
authors.affiliation: †Department of Mechanical and Automation Engineering (Biomedical Engineering), ‡Department of Electronic Engineering (Biomedical Engineering), §School of Pharmacy, ∥Shun Hing Institute of Advanced Engineering, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
authors.forename: Jinming
authors.initials: J
authors.lastname: Li
authors.affiliation: †Department of Mechanical and Automation Engineering (Biomedical Engineering), ‡Department of Electronic Engineering (Biomedical Engineering), §School of Pharmacy, ∥Shun Hing Institute of Advanced Engineering, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
authors.forename: Kongchang
authors.initials: K
authors.lastname: Wei
authors.affiliation: †Department of Mechanical and Automation Engineering (Biomedical Engineering), ‡Department of Electronic Engineering (Biomedical Engineering), §School of Pharmacy, ∥Shun Hing Institute of Advanced Engineering, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
authors.forename: Yang J
authors.initials: YJ
authors.lastname: Xu
authors.affiliation: †Department of Mechanical and Automation Engineering (Biomedical Engineering), ‡Department of Electronic Engineering (Biomedical Engineering), §School of Pharmacy, ∥Shun Hing Institute of Advanced Engineering, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
authors.forename: Lok Wai C
authors.initials: LW
authors.lastname: Ho
authors.affiliation: †Department of Mechanical and Automation Engineering (Biomedical Engineering), ‡Department of Electronic Engineering (Biomedical Engineering), §School of Pharmacy, ∥Shun Hing Institute of Advanced Engineering, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
authors.forename: Meiling
authors.initials: M
authors.lastname: Zhu
authors.affiliation: †Department of Mechanical and Automation Engineering (Biomedical Engineering), ‡Department of Electronic Engineering (Biomedical Engineering), §School of Pharmacy, ∥Shun Hing Institute of Advanced Engineering, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
authors.forename: Kenneth K W
authors.initials: KK
authors.lastname: To
authors.affiliation: †Department of Mechanical and Automation Engineering (Biomedical Engineering), ‡Department of Electronic Engineering (Biomedical Engineering), §School of Pharmacy, ∥Shun Hing Institute of Advanced Engineering, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
authors.forename: Chung Hang J
authors.initials: CH
authors.lastname: Choi
authors.affiliation: †Department of Mechanical and Automation Engineering (Biomedical Engineering), ‡Department of Electronic Engineering (Biomedical Engineering), §School of Pharmacy, ∥Shun Hing Institute of Advanced Engineering, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
authors.forename: Liming
authors.initials: L
authors.lastname: Bian
mesh_terms: D002454:Cell Differentiation; D006046:Gold / Q000737:chemistry*; D006801:Humans; D007211:Indoles / Q000737:chemistry*; D042541:Intracellular Space / Q000737:chemistry*; D059630:Mesenchymal Stem Cells / Q000737:chemistry* / Q000166:cytology*; D035683:MicroRNAs / Q000032:analysis*; D015335:Molecular Probes / Q000737:chemistry*; D015394:Molecular Structure; D053758:Nanoparticles / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*
chemical_list: D007211:Indoles; D035683:MicroRNAs; D015335:Molecular Probes; D011108:Polymers; C568283:polydopamine; D006046:Gold