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  • The authors report no conflict of interest br Corresponding

    2019-10-21

    The authors report no conflict of interest.
    Corresponding author: Beryl Manning-Geist, MD.
    [email protected]
    Contents lists available at ScienceDirect
    Sensors and Actuators B: Chemical
    journal homepage: www.elsevier.com/locate/snb
    A novel cytosensor for capture, detection and release of breast cancer Epoprostenol T based on metal organic framework PCN-224 and DNA tetrahedron linked dual-aptamer
    Dan Oua, Duanping Suna,b, , Zhixian Lianga, Bowen Chenc, Xiangan Lind, Zuanguang Chena,
    a School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, 510006, China
    b Center for Drug Research and Development, Guangdong Pharmaceutical University, Guangzhou, 510006, China
    c School of Public Health, Sun Yat-Sen University, Guangzhou, 510080, China
    d Department of Cancer Chemotherapy, Sun Yat-Sen Memorial Hospital of Sun Yat-Sen University, Guangzhou, 510120, China
    Keywords:
    Electrochemical cytosensor
    Dual-aptamer
    Breast cancer cells
    Metal organic framework
    DNA tetrahedron 
    A convenient and efficient strategy for detecting cancer cells at preclinical stages is one of the dominant chal-lenges in early cancer diagnostics. In this work, a sandwich-type cytosensor was structured to analyze cancer cells based on metal organic framework PCN-224 and DNA tetrahedron linked dual-aptamer. Firstly, the tet-rahedral DNA nanostructures linked dual aptamers (AS1411 and MUC1) immobilizing on the gold electrode (GE) surface as bio-recognition elements can capture the MCF-7 cancer cells and improve the density and orientation of surface nanoprobes. Then, the novel metal organic framework PCN-224 homogeneously decorated by Pt nanoparticles was modified by the G-quadruplex/hemin DNAzyme, horseradish peroxidase (HRP) and dual-aptamer. The fabricated nanoprobes were applied to catalyze the oxidation of hydroquinone (HQ) with hy-drogen peroxide (H2O2) for amplifying the electrochemical signal. The results indicated that the linear response of the aptasensor ranged from 20 to 1 × 107 cells/mL and the detection limit was 6 cells/mL. Finally, we per-formed an electrochemical reductive desorption to break goldethiol bond and release all compounds on the electrode surface for analyzing the viability of collected cells and regenerating the cytosensor. This work can be extended to other cancer cells by using specific type aptamers and has widely applications prospect in point-of-care cancer diagnosis.
    1. Introduction
    Cancer, the occurrence of which is increasing due to the increasing prevalence of risk factors such as the growth and aging of the popula-tion, being overweight, lack of physical exercise, smoking, and chan-ging reproductive models, is today's most pressing health concern [1]. The incidence of breast cancer has been increasing year by year in re-cent years, ranking first among female malignant tumors. At present, several approaches have been developed for cancer cells detection in-cluding flow cytometry [2], fluorescence analysis [3], inductively coupled plasma mass spectrometry (ICP-MS) [4], electro-chemiluminescence [5], and electrochemical sensor [6,7]. Wherein, electrochemical sensor has showed special importance in the food analysis [8], biological analysis [9,10] and environmental pollutants analysis [11] because of merits of low cost, simple instrumentation, quick feedback and acceptable sensitivity.
    The aptamer is a synthetic nucleic acid screened by SELEX (sys-tematized exponentially enriched ligand) [12], which is a powerful molecular recognition system with specifically decorating a variety of functional ligands, such as the whole cell, protein and so on. Compared with antibody, aptamer provides good stability, modification and spe-cificity, thus has been widely applied in the biomedical fields including drug delivery [13,14], cellular immunity [15], bioimaging [16,17] and disease diagnosis [18]. Therefore, the introduction of aptamer as target recognition molecule into the electrochemical cytosensor can improve the selectivity of tumor cells capture. To efficiently capture the MCF-7 cells, aptamers were introduced for targeting guanosine-rich oligonu-cleotide 100 (AS1411 aptamer), human epidermal growth factor re-ceptor 2 (HER2 aptamer), epithelial cell adhesion molecule (EpCAM aptamer), and mucin 1 (MUC1 aptamer) [19–21]. However, single-stranded DNA aptamers attached to electrodes are often entangled and aggregated, hindering the effective binding of aptamers to cells.