A versatile proximity-dependent probe based on light-up DNA-scaffolded silver nanoclusters

Abstract

It is well-known that proximity-dependent probes containing an analyte recognization site and a signal formation domain could be assembled specifically into a sandwich-like structure (probe–analyte–probe) via introducing an analyte. In this work, using the design for zirconium ion (Zr⁴⁺) detection as the model, we develop a novel and reliable proximity-dependent DNA-scaffolded silver nanocluster (DNA/AgNC) probe for Zr⁴⁺ detection via target-induced emitter proximity. The proposed strategy undergoes the two following processes: target-mediated emitter pair proximity as target recognition implement and the synthesis of DNA/AgNCs with fluorescence as a signal reporter. Upon combination of the rationally designed probe with Zr⁴⁺, the intact templates were obtained according to the –PO₃²⁻−Zr⁴⁺−PO₃²⁻– pattern. The resultant structure with an emitter pair serves as a potent template to achieve highly fluorescent DNA/AgNCs. To verify the universality of the proposed proximity-dependent DNA/AgNC probe, we extend the application of the proximity-dependent probe to DNA and adenosine triphosphate (ATP) detection by virtue of a specific DNA complementary sequence and ATP aptamer as a recognition unit, respectively. The produced fluorescence enhancement of the DNA/AgNCs in response to the analyte concentration allows a quantitative evaluation of the target, including Zr⁴⁺, DNA, and ATP with detection limits of ∼3.00 μM, ∼9.83 nM, and ∼0.81 mM, respectively. The proposed probe possesses good performance with simple operation, cost-effectiveness, good selectivity, and without separation procedures.