Ultrasensitive electrochemical biosensor using carboxylated graphitic carbon nitride-nanogold composite for SARS-CoV-2 receptor binding proteinRamya, P.R. (Avtor) Sarup, Shivmuni (Avtor) Jerman, Ivan (Avtor) Chouhan, Raghuraj S. (Avtor) Gandhi, Sonu (Avtor) graphitic carbon nitrideThe global response to COVID-19 has exposed critical gaps in rapid, ultrasensitive, and accessible diagnostic technologies, particularly in decentralised and low-resource environments. Herein, we report the development of an electrochemical biosensor designed for ultrasensitive detection of the SARS-CoV-2 spike receptor-binding domain (RBD) protein. This platform was rationally engineered nanocomposite combined with carboxylated graphitic carbon nitride (cGCN) and gold nanoparticles (AuNPs), which synergistically enhance surface reactivity, electron transfer efficiency, and biomolecular interface stability. Hybrid nanomaterials can overcome the kinetic and sensitivity barriers of traditional biosensors, and a cGCN/AuNP hybrid was fabricated on fluorine-doped tin oxide (FTO) electrodes and functionalized with in-house generated anti-RBD antibodies. Comprehensive physicochemical characterisation confirmed the successful integration and surface engineering of the composite. Using Differential Pulse Voltammetry, the sensor achieved a limit of detection (LOD) of 0.8 fM and demonstrated limit of quantification (LOQ) of 2.65 fM. This performance exceeds that of many existing SARS-CoV-2 antigen based biosensors and underscores the utility of rational nanomaterial design for high-precision point-of-care viral diagnostics. This approach is readily adaptable for detecting emerging viral pathogens and supporting future pandemic preparedness.Elsevier20242025-12-15 11:18:10Neznano24711UDK: 544.5/.6ISSN pri članku: 1095-9149DOI: 10.1016/j.microc.2025.114455COBISS_ID: 241950723Nizozemskasl© 2025 The Author(s).