Three-dimensional DNA structures in situ decorated with metal nanoclusters for dual-mode biosensing of glucose

The monitoring of blood glucose levels is essential to the diagnosis and management of diseases, especially diabetes. Thus, it is of great importance to develop a simple, accurate and sensitive method for glucose detection. Herein, the three-dimensional DNA flowers-templated Ag nanoclusters (DFs/AgNCs) with enhanced fluorescent brightness and good stability are in situ synthesized via rolling circle amplification (RCA), which are further successfully applied for the construction of fluorescent/electrochemical dual-mode glucose biosensor. In this assay, the AgNCs encapsulated in DFs can be etched by H2O2 that is generated from the process of glucose oxidase (GOx)-catalyzed glucose oxidation, resulting in the release of Ag+ to facilitate the signal-off fluorescent detection of glucose. Based on the coordination interaction of cytosine-Ag+-cytosine (C-Ag+-C), the liberated Ag+ further induces the conformation switch of ferrocene (Fc)-labeled DNA capture probe (Fc-DNA) with C-rich sequence on Au electrode, leading to the signal-on electrochemical detection of glucose. The proposed DFs/AgNCs-based fluorescent/electrochemical dual-mode biosensor has achieved the sensitive and selective detection of glucose in human serums with good accuracy and reliability, which not only provides a rapid, reliable and accurate method for glucose detection but also opens a new avenue to the development of DNA nanotechnology-based biosensing strategies.