Immobilization of biosensors in or on a functional material is critical for subsequent device development and translation to wearable technology. Here we present the development and assessment of an immobilized quantum dot - transcription factor - nucleic acid complex for progesterone detection as a first step toward such device integration. The sensor is composed of a polyhistidine-tagged transcription factor linked to a quantum dot and a fluorophore-modified cognate DNA, and embedded within a hydrogel as an immobilization matrix. The hydrogel is optically transparent, soft, and flexible as well as traps the quantum dot - transcription factor DNA assembly but allows free passage of the analyte, progesterone. Upon progesterone exposure, DNA dissociates from the quantum dot - transcription factor DNA assembly resulting in an attenuated ratiometric fluorescent output via Förster resonance energy transfer. The sensor performs in a dose-dependent manner with a limit of detection of 55 nM. Repeat analyte measurements are also similarly successful. Our approach combines a systematically characterized hydrogel as an immobilization matrix and a transcription factor - DNA binding as a recognition/ transduction element, offering a promising framework for future biosensor devices based upon allosteric transcription factor.< Leer menos