MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering & Key Laboratory of Micro-Systems and Micro-Structures, Ministry of Education, Harbin Institute of Technology, Harbin 150001, People's Republic of China.
Anal Chem. 2021 Aug 31;93(34):11686-11691. doi: 10.1021/acs.analchem.1c01311. Epub 2021 Aug 16.
Single-nanoparticle-level sensing allows us to measure individual molecular interactions and probe environmental stimuli at nanometer-scale resolution. Despite these premises, limited success has been met hitherto due to the demanding challenge to distinguish a dimmed signal from a noisy background. Here, we describe an approach for high-sensitivity single-nanoparticle-level sensing of divalent copper (Cu) ions through near-infrared-to-visible upconversion luminescence against a near-null background. This nanosensor utilizes ytterbium- (Yb) and erbium (Er)-doped sodium yttrium fluoride (NaYF) upconversion nanoparticles (UCNPs) (maximal emission at 540 nm when excited at 980 nm) as an energy donor, of which the surface attaches Cu-dependent DNAzymes labeled with BHQ1 dye (Black Hole Quencher 1, maximal absorption at 548 nm) as energy acceptors. Adding a hint amount of Cu ions resulted in the cleavage of a BHQ1-containing moiety in DNAzymes, thus turning on upconversion luminescence for sensitive detection. Indeed, this approach allows us to perform single-nanoparticle-level detection of Cu ions with extraordinary signal-to-noise ratios (SNRs, >277) for all measured concentrations that cover 3 orders of magnitude (from sub-nM to μM). Importantly, a limit of detection of 220 pM was achieved, about sevenfold lower than the one at the ensemble level. Moreover, a stochastic particle-to-particle sensing behavior was also identified, featuring single-nanoparticle-level detection. This work untaps the usage of UCNPs for high-sensitivity single-nanoparticle-level biosensing.
单颗粒水平的传感使我们能够测量单个分子相互作用，并以纳米级分辨率探测环境刺激。尽管有这些前提，但迄今为止，由于需要区分微弱信号和噪声背景的挑战性，取得的成功有限。在这里，我们描述了一种通过近红外到可见上转换发光在近零背景下对二价铜（Cu）离子进行高灵敏度单颗粒水平传感的方法。这种纳米传感器利用掺镱（Yb）和铒（Er）的氟化钠钇（NaYF）上转换纳米粒子（UCNP）（在 980nm 激发时最大发射在 540nm）作为能量供体，其表面附着 Cu 依赖性 DNA 酶，标记有 BHQ1 染料（黑洞猝灭剂 1，在 548nm 处最大吸收）作为能量受体。添加少量的 Cu 离子会导致 DNA 酶中含有 BHQ1 的部分断裂，从而开启上转换发光以进行灵敏检测。事实上，这种方法允许我们对 Cu 离子进行单颗粒水平检测，所有测量浓度的信号噪声比（SNR，>277）都非常高，涵盖了 3 个数量级（从亚纳摩尔到微摩尔）。重要的是，实现了 220pM 的检测限，比在整体水平上的检测限低约 7 倍。此外，还确定了一种随机的颗粒到颗粒传感行为，具有单颗粒水平的检测。这项工作利用了 UCNP 进行高灵敏度单颗粒水平生物传感。
