Tan Hongliang, Tang Gonge, Ma Chanjiao, Li Qian
Key Laboratory of Functional Small Organic Molecule, Ministry of Education, Key Laboratory of Chemical Biology, Jiangxi Province, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang, 330022, PR China.
Key Laboratory of Functional Small Organic Molecule, Ministry of Education, Key Laboratory of Chemical Biology, Jiangxi Province, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang, 330022, PR China.
Anal Chim Acta. 2016 Feb 18;908:161-7. doi: 10.1016/j.aca.2015.12.035. Epub 2016 Jan 5.
In this work, we developed a simple and sensitive method for the detection of cysteine (Cys) by employing terbium ion (Tb(3+))-promoted G-qudraplex (G4/Tb) as a luminescent probe, which is based on Ag(+)-mediated conformational change of G4/Tb. Due to Ag(+) is able to compete with Tb(3+) to bind guanine at G4, the presence of Ag(+) can lead to the formation of G4/Tb-Ag(+) complex and disrupt the structure of G4/Tb. Meanwhile, the binding of Ag(+) with G4/Tb will also cause the alteration of the excited state of G4 and more efficient energy transfer from G4 to Tb(3+), enhancing the luminescence of G4/Tb. However, upon the addition of Cys, Ag(+) will be released from G4/Tb-Ag(+) complex because of the high affinity of Cys to Ag(+). This results in the re-formation of the conformation of G4/Tb and the decrease of the luminescence of G4/Tb. So, Ag(+)-enhanced luminescence of G4/Tb is associated with its conformational transformation. As a luminescent probe for Cys, G4/Tb not only shows excellent selectivity and sensitivity with a detection limit of 20 nM, but also possesses the features of simple preparation, easy reproducibility, and eliminating the interferences from background fluorescence. We envision that the presented strategy might provide new insight into the biosensing applications of lanthanide complex.
在本工作中，我们开发了一种简单且灵敏的检测半胱氨酸（Cys）的方法，该方法采用铽离子（Tb(3+)）促进的G-四链体（G4/Tb）作为发光探针，其基于Ag(+)介导的G4/Tb构象变化。由于Ag(+)能够与Tb(3+)竞争结合G4上的鸟嘌呤，Ag(+)的存在会导致形成G4/Tb-Ag(+)复合物并破坏G4/Tb的结构。同时，Ag(+)与G4/Tb的结合也会导致G4激发态的改变以及从G4到Tb(3+)更有效的能量转移，增强G4/Tb的发光。然而，加入Cys后，由于Cys对Ag(+)的高亲和力，Ag(+)会从G4/Tb-Ag(+)复合物中释放出来。这导致G4/Tb构象重新形成以及G4/Tb发光减弱。所以，Ag(+)增强的G4/Tb发光与其构象转变相关。作为Cys的发光探针，G4/Tb不仅具有出色的选择性和灵敏度，检测限为20 nM，还具有制备简单、易于重现以及消除背景荧光干扰的特点。我们设想所提出的策略可能为镧系元素配合物的生物传感应用提供新的见解。
