3D Matrix-Arranged AuAg Nanoclusters As Electrochemiluminescence Emitters for Click Chemistry-Driven Signal Switch Bioanalysis
Fang Yang, Xinya Jiang, Wenbin Liang, Yaqin Chai, Ruo Yuan, Ying Zhuo
Abstract
We hereby described an electrochemiluminescence (ECL) biosensor for glutathione (GSH) based on a 3D DNA matrix with ordered binding sites and cavity structure that self-assembled from tetrahedral DNA blocks (TDBs). First, the alkyne-labeled TDBs were employed to build an alkyne-rich 3D matrix (C≡C-3DM) on the electrode surface. Then, the GSH-induced click chemistry was triggered as a signal switch to introduce the large amounts of N3-DNA decorated AuAg nanoclusters (N3–AuAg NCs) into C≡C-3DM for signal output. In particular, the presence of GSH could induce the formation of GSH–Cu(I) complex by the redox reaction between GSH and Cu(II), which could act as an initiator to link the N3–AuAg NCs with C≡C-3DM according to the Huisgen 1,3-dipolar cycloaddition reaction. By this way, numerous N3–AuAg NCs were orderly bonded to the 3D matrix to effectively reduce their agglomeration and inner filter effect, achieving a remarkable ECL enhancement. As a result, the proposed GSH biosensor showed a wide linear range from 5 to 200 μM with a low detection limit of 0.90 μM. In general, this work provided a rapid, highly efficient, and convenient signal amplification for small-molecule detection and broadened the application of TDBs in biosensing.