Enzymatic ablation of bimetallic Au@Ag nanocomposites enabling the smartphone-based colorimetric visualization of S1 nuclease

Abstract

S1 nuclease is an important endonuclease involved in multiple biological processes. It is essential to develop suitable detection methods to analyze the S1 nuclease activity for further understanding its biological functions. Although conventional methods for S1 nuclease detection have been well-designed including the gold nanoparticles (AuNPs)-related analytical methods. It still remains challenges in further improving their detection performances. To address these challenges, we report a novel smartphone-based colorimetric sensing method using the bimetallic Au@Ag nanocomposites (Au@Ag NCs) to realize the portable, sensitive, analytical instrument-free, and visual detection of S1 nuclease in real samples. In this method, the bare AuNPs was primarily modified with L1 DNA for supporting the silver (Ag) shell. With the formation of Ag shell, the prepared Au@Ag NCs display the enhanced localized surface plasma resonance (LSPR) effect by producing the characteristic UV–vis absorption peak of Ag (Abs_Ag), while the Abs_Au/Abs_Ag values will be promoted by the enzymatic ablation of Ag shell when L1 DNA was cleaved by S1 nuclease. Thus, Au@Ag NCs allow the colorimetric, sensitive and selective sensing toward S1 nuclease activity with the detection linear range varied from 0.1 to 50 U/mL and the detection limit as low as 0.02 U/mL. Furthermore, the colorimetric signals change also display the obvious color change in Au@Ag NCs and a smartphone-based sensing platform has been constructed to reveal the Red/Green/Blue (RGB) quantification and visual analysis of S1 nuclease in different scenarios. Therefore, this method will hold great potential in realizing the S1 nuclease detection with preferable detection performances.