Department of Chemistry, Nanchang University, Nanchang 330031, China.
Talanta. 2014 Jan;118:339-47. doi: 10.1016/j.talanta.2013.09.021. Epub 2013 Oct 3.
We have developed a simple, rapid and label-free sensor for the essential biological OH radicals based on the fluorescence quenching of DNA-templated Ag nanoclusters (DNA-Ag NCs). The OH radicals generated from the Fenton reagent attack and cleave the DNA template, which disturbs the microenvironments around Ag NCs, resulting in spontaneous aggregation due to the lack of stabilization and further the quenching of the Ag NCs fluorescence. These changes in fluorescence intensity allow sensing of OH radicals with good sensitivity and selectivity under optimal conditions. The sensor can be also applied for quantifying the radical scavenging action of antioxidants. Various characterizations including absorption spectra, fluorescence lifetimes, light scattering (LS) spectra, transmission electron microscopy (TEM), dark field light scattering imaging, and circular dichroism (CD) spectrometry have been employed to illustrate the proposed sensing mechanism. Further investigations demonstrate that the fluorescent probe could penetrate into intact cell membranes to selectively detect intracellular OH radicals induced by the phorbol myristate acetate (PMA) stimulation. These advantageous characteristics make the fluorescent DNA-Ag NCs potentially useful as a new candidate to monitor OH in broad biosystems.
我们基于荧光猝灭的 DNA 模板银纳米簇（DNA-Ag NCs）开发了一种用于检测基本生物 OH 自由基的简单、快速且无需标记的传感器。Fenton 试剂产生的 OH 自由基攻击并切割 DNA 模板，这会扰乱 Ag NCs 周围的微环境，由于缺乏稳定性，Ag NCs 会自发聚集，从而导致荧光猝灭。在最佳条件下，这些荧光强度的变化可以实现对 OH 自由基的高灵敏度和选择性检测。该传感器还可用于定量测定抗氧化剂的自由基清除作用。各种表征，包括吸收光谱、荧光寿命、光散射（LS）光谱、透射电子显微镜（TEM）、暗场光散射成像和圆二色性（CD）光谱，都被用来阐明所提出的传感机制。进一步的研究表明，荧光探针可以穿透完整的细胞膜，选择性地检测由佛波酯（PMA）刺激诱导的细胞内 OH 自由基。这些有利的特性使得荧光 DNA-Ag NCs 有可能成为监测广泛生物体系中 OH 的新候选物。
