Development of itch biosensors with engineering membrane receptors that are coupled to field-effect transistors.

Biosensors inspired by biological sensory systems are valuable tools for detecting physiological and environmental stimuli with high degrees of specificity and sensitivity. An itch irritant biosensor to detect environmental changes or pruritogenic substances in human blood or tissues highly associated with inflammation and prevalent conditions like atopic dermatitis (AD) has not been developed. To address this gap, we developed a novel bioelectronic sensor by integrating the human itch receptor Mas-related G-protein-coupled receptor X2 (MRGPRX2) with a graphene field-effect transistor (GFET). This MRGPRX2-GFET biosensor covalently immobilizes functional receptors, enabling direct conversion of ligand-binding events into quantifiable electrical signals. We demonstrate that the sensor can detect known MRGPRX2 agonists with exceptional sensitivity and specificity, achieving a detection limit for SP at approximately 7 pM. Molecular dynamics (MD) simulations and mutational effects reveal that ligand binding induces cytoplasmic conformational rearrangements in MRGPRX2, strengthening receptor-graphene coupling and providing a mechanistic basis for signal transduction. Importantly, the biosensor effectively distinguishes plasma samples from AD patients and healthy controls by capturing different electrical signal responses. In our study, we establish a versatile platform for diagnosing and subtyping chronic itch disorders and offer a generalizable strategy for developing membrane receptor-based multiplexed "itch-print" biosensors.