Marieeswaran Muppidathi, Panneerselvam Perumal
Department of Chemistry, SRM Institute of Science and Technology Kattankulathur 603 203 Tamil Nadu India
RSC Adv. 2020 Jan 22;10(7):3705-3714. doi: 10.1039/c9ra08274c.
A novel fluorescent biosensor has been designed and synthesized comprising a magnetic nanoscale metal-organic framework (MNMOF) functionalized with fluorescein amidite (FAM)-labeled ssDNA. It exhibits good sensitivity and selectivity for Hg(ii) cations over other co-existing metal ions. MNMOF was fabricated by a one-pot synthetic method and it was successfully characterized with various techniques such as UV-visible spectroscopy, fluorescence spectroscopy, Fourier-transform infrared (FT-IR) spectrometry, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The FAM-labeled ssDNA was adsorbed onto the surface of MNMOF through π-π stacking and electrostatic interactions, which resulted in the partial quenching of its fluorescence intensity (65%). Upon the subsequent addition of Hg(ii) ions, the fluorescence intensity was further quenched at 52%, due to the re-adsorption of dsDNA onto the surface of MNMOF. Thus, the FAM-labeled ssDNA showed a drastic decrease in fluorescence intensity with Hg(ii). This quenching-quenching mechanism led to a linear response in the fluorescence intensity to Hg(ii) concentration ( = 0.934) with a low detection limit of 8 nM. The specific merits of MNMOF make it an ideal platform for mercury sensor applications.
一种新型荧光生物传感器已被设计并合成，它由用荧光素亚磷酰胺（FAM）标记的单链DNA（ssDNA）功能化的磁性纳米级金属有机框架（MNMOF）组成。与其他共存金属离子相比，它对Hg(ii)阳离子表现出良好的灵敏度和选择性。MNMOF通过一锅合成法制备，并通过紫外可见光谱、荧光光谱、傅里叶变换红外（FT-IR）光谱、X射线衍射（XRD）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）和X射线光电子能谱（XPS）等多种技术成功进行了表征。FAM标记的ssDNA通过π-π堆积和静电相互作用吸附在MNMOF表面，导致其荧光强度部分猝灭（65%）。随后加入Hg(ii)离子后，由于双链DNA（dsDNA）重新吸附在MNMOF表面，荧光强度进一步猝灭52%。因此，FAM标记的ssDNA在Hg(ii)存在下荧光强度急剧下降。这种猝灭-猝灭机制导致荧光强度对Hg(ii)浓度呈线性响应（ = 0.934），检测限低至8 nM。MNMOF的独特优点使其成为汞传感器应用的理想平台。
