Arginine-Specific Molecularly Imprinted Polymer-Based Laser-Induced Graphene Flexible Sensor

Non-invasive monitoring of biomarkers is crucial for the wide adoption of health monitoring and the early detection of health conditions. L-Arginine, a conditionally essential amino acid with a variety of significant physiological roles, is critical for the pathogenesis of various cardiovascular diseases (CVD) such as endothelial dysfunction, neurodegenerative disorders, and overall homeostasis. However, current methods of detection of L-Arginine are unsuitable for continuous monitoring due to their heavy requirements on resources and invasive sampling. Here, we describe the fabrication of an L-Arginine-specific electrochemical sensor by integrating a Molecularly Imprinted Polymer (MIP) on a PEDOT:PSS modified Laser-Induced Graphene (LIG) electrode on a flexible substrate. The MIPs function as sensitive and selective synthetic receptors for L-Arginine, while the PEDOT:PSS electrodeposited LIG electrode provides low impedance and a high sensitivity detection. The MIP-PEDOT:PSS-LIG platform uses Electrochemical Impedance Spectroscopy (EIS) and demonstrates exceptional analytical performance, achieving a low Limit of Detection (LOD) (~1 nm) and a wide linear dynamic range (1 nM to 1 mM), effectively covering the physiologically relevant concentrations of arginine in sweat. The sensor exhibited high selectivity against structurally similar amino acids (lysine, histidine, and citrulline) and maintained robust linearity (R² ~ 0.98) when tested in an artificial sweat medium. Furthermore, the device exhibited excellent reusability and stability via controlled electrostatic regeneration, demonstrating robustness and applicability within artificial sweat. In summary, a sensitive and selective MIP is developed which enables non-invasive sensing of L-arginine with readily made flexible electrodes and provides a promising device for next-generation point-of-care diagnostics and health monitoring.