Ultrasensitive Nanofluidic Detection of 17β-Estradiol in Natural Water by DNA Circuit-Mediated Hyperbranched DNA...

The pervasive detection of trace 17β-estradiol (E2) in aquatic ecosystems necessitates innovative analytical platforms capable of ultrahigh sensitivity and field applicability. Herein, we report a nanofluidic biosensor integrating polydopamine-functionalized graphene oxide (PDA/GO) membranes with an entropy-driven DNA circuit and hyperbranched DNA nanowires (HDW) for femtomolar-level E2 quantification. Leveraging E2-specific aptamer recognition, the system triggers an entropy-driven DNA circuit and subsequent hierarchical assembly of guanine quadruplex (G4)-enriched HDW nanostructures on nanochannel surfaces, amplifying interfacial electronegativity through phosphate backbone accumulation. This charge amplification synergizes with subnanometer-confined ion transport modulation, achieving an 8.19-fold current enhancement upon E2 binding. The optimized biosensor exhibited a linear dynamic range spanning five orders (1 fM to 100 pM) with a detection limit of 0.39 fM, comparable to conventional LC-MS/MS for the analysis of E2. Rigorous specificity testing demonstrated high anti-interference against structural analogs and endocrine disruptors. Practical validation in real water samples (Yellow River, Heihu Spring, Qian Lake, and an aquaculture pond) demonstrated recovery rates of 91.2-109%, supported by robust stability and environmental resilience. This work establishes nucleic acid nanotechnology-enhanced nanofluidics, addressing critical gaps in on-site endocrine disruptor monitoring through synergistic molecular recognition and interfacial charge engineering.