Graphdiyne-PtCu hollow nanocubes-cooperated dual-engine hairpin assembler toward amplifiable electrochemical biosensing.

Developing graphdiyne-PtCu hollow nanocubes (GPtCu)-cooperated dual-engine hairpin assembler (dEHA) for amplifying electrochemical response of 17β-estradiol (E2) might be intriguing and desirable, particularly in the area of environmental analysis. Herein, we propose the first design of GPtCu-coupled dEHA amplification for constructing electrochemical biosensor sensitively responsive to E2. The modification of GPtCu and AuNPs in the electrode surface aims to enhance electronic conductivity, increase electroactive surface area, and provide more accessible Au-S binding sites for immobilizing electroactive ferrocene (Fc)-labeled signaling hairpin probe. An E2-recognizable strand encoding specific aptamer sequence and a translator strand are designed to form a duplex strand for interpreting the presence and variation of E2. As such, the progressive dEHA operation is executed via consecutive hybridization and strand migration reaction among three functional hairpins. During the process, the translating and recognizing modules are rationally displaced and functioned as two uninterrupted engines to implement repetitive recycling events through cooperatively catalyzing the transient depletion of reactive intermediates, thereby achieving rapid transduction and efficient amplification. As a result, numerous Fc tags in the final duplex products are oriented close in the electrode sensing interface to output linearly E2-dependent current signal, featuring superior reaction kinetics, high specificity and sensitivity. Thus, our strategy would suggest a reliable analytical tool and a universal biosensing paradigm for monitoring diverse trace-level environmental endocrine disruptors (EEDs).