Surface Immobilized Nucleic Acid–Transcription Factor Quantum Dots for Biosensing

Immobilization of biosensors on surfaces is a key step toward development of devices for real‐world applications. Here the preparation, characterization, and evaluation of a surface‐bound transcription factor–nucleic acid complex for analyte detection as an alternative to conventional systems employing aptamers or antibodies are described. The sensor consists of a gold surface modified with thiolated Cy5 fluorophore‐labeled DNA and an allosteric transcription factor (TetR) linked to a quantum dot (QD). Upon addition of anhydrotetracycline (aTc)—the analyte—the TetR‐QDs release from the surface‐bound DNA, resulting in loss of the Förster resonance energy transfer signal. The sensor responds in a dose‐dependent manner over the relevant range of 0–200 µm aTc with a limit of detection of 80 nm . The fabrication of the sensor and the subsequent real‐time quantitative measurements establish a framework for the design of future surface‐bound, affinity‐based biosensors using allosteric transcription factors for molecular recognition.A Wearable Sensor for Hormones Based on a Native Microbial Sensin