Key Laboratory of Theoretical and Computational Photochemistry, College of Chemistry , Beijing Normal University , Beijing 100875 , China.
The Aerospace City School of the High School Affiliated to Renmin University of China , Beijing 100087 , China.
ACS Appl Mater Interfaces. 2018 Aug 1;10(30):25621-25628. doi: 10.1021/acsami.8b03429. Epub 2018 Jul 18.
An upconversion nanoparticle (UCNP)-based fluorescence resonance energy-transfer (FRET) strategy is normally restricted by the complicated preparations, low energy-transfer efficiency, and the challenge on improving specificity. Herein, simple DNA-functionalized UCNPs were designed as energy donors for constructing a FRET-based probe to detect the liver-specific microRNA 122 (miR-122). To improve FRET efficiency, UCNPs were constructed with confined core-shell structures, in which emitting ions were precisely located in the thin shell to make them close enough to external energy acceptors. Subsequently, capture DNA was simply functionalized on the outer surface of UCNPs based on ligand exchange that contributed to shortening the energy-transfer distance without extra modification. To gain high specificity, the donor-to-acceptor distance of FRET was controlled by a sandwich DNA hybridization structure using two shorter DNAs with designed complementary sequences (capture DNA and dye-labeled report DNA) to capture the longer target of miR-122. Therefore, the sensitive detection of miR-122 was achieved based on the decreased signals of UCNPs and the increased signals of the dye labeled on reported DNA. With good biocompatibility, this method has been further applied to cancer cell imaging and in vivo imaging, which opened up a new avenue to the sensitive detection and imaging of microRNA in biological systems.
上转换纳米粒子（UCNP）基于荧光共振能量转移（FRET）的策略通常受到复杂的制备、低能量转移效率以及提高特异性的挑战的限制。在此，设计了简单的 DNA 功能化 UCNP 作为能量供体，用于构建基于 FRET 的探针以检测肝特异性 microRNA 122（miR-122）。为了提高 FRET 效率，UCNP 采用受限的核壳结构构建，其中发射离子精确地位于薄壳中，以使它们足够接近外部能量受体。随后，基于配体交换在 UCNP 的外表面上简单地功能化捕获 DNA，这有助于缩短能量转移距离，而无需额外修饰。为了获得高特异性，通过使用具有设计的互补序列的两个较短 DNA 的夹心 DNA 杂交结构来控制 FRET 的供体-受体距离，以捕获较长的 miR-122 靶标。因此，基于 UCNP 信号降低和报告 DNA 上标记的染料信号增加，实现了 miR-122 的灵敏检测。该方法具有良好的生物相容性，已进一步应用于癌细胞成像和体内成像，为生物系统中 microRNA 的灵敏检测和成像开辟了新途径。
