Chemical reaction kinetics regulated dual-signal sensing system for discriminating EV-A71 and CV-A16

A dual-signal system was developed to detect Enterovirus A71 (EV-A71, T_EV) and Coxsackievirus A16 (CV-A16, T_CV), leveraging the regulatory mechanisms of chemical reactions. MOF_Fe acts as a catalyst, MOF_Cr as a Fe²⁺ reservoir. Specific DNA sequences (P_EV, P_CV), which are complementary to T_EV and T_CV respectively, are employed to block the pores of MOF_Cr and MOF_Fe, thereby forming DNA-gated MOFs: MOF_Cr/Fe²⁺/P_CV and MOF_Fe/P_EV. These constructs are further integrated with hyaluronic acid (HA) and glutathione (GSH) modified gold electrodes to create MOF_Fe/P_CV + MOF_Cr/Fe²⁺/P_EV@HA@GSH@Au NPs@GCE. T_CV activates the catalytic core of MOF_Fe in a medium containing hydrogen peroxide (H₂O₂) and hydroquinone (HQ), which then catalyzes the oxidation of HQ to benzoquinone (BQ), followed by the addition of potassium ferrocyanide (K₃[Fe(CN)₆]). T_EV activates MOF_Cr, triggering the release of Fe²⁺. Due to the lower catalytic activity of MOF_Cr, only a small fraction of Fe²⁺ and HQ is oxidized to Fe³⁺ and BQ, while the majority of Fe²⁺ coordinates with K₃[Fe(CN)₆] to form Prussian blue (PB). With both viruses, the simultaneous activation of MOF_Fe and MOF_Cr enhances the oxidation of Fe²⁺ and HQ, leading to minimal PB formation. As a result, the concentrations of PB, BQ and K₃[Fe(CN₎₆] are selectively modulated in this strategy, leading to unique signal patterns for each target (" Γ" for T_CV, "↘" for T_EV, and "∩" for both). This enables their identification and discrimination. Importantly, this strategy demonstrates excellent analytical performance, achieving a detection range from 10^-7 M to 10^-13 M, even in 5% serum.