Facile and label-free electrochemical detection of myasthenia gravis-associated AChR antibodies using a laser-induced graphene immunoplatform.

Myasthenia gravis (MG) is a chronic autoimmune neuromuscular disorder characterized by progressive muscle weakness that can severely impact patient quality of life and may lead to life-threatening complications if not diagnosed in a timely manner. Traditional serological diagnostic methods are often complex, time-consuming, and less accessible. To address these limitations, we developed a novel label-free electrochemical immunosensor. It uses laser-induced graphene (LIG) electrodes co-functionalized with gold nanoparticles (AuNPs) and copper ferrite nanoparticles (CuFe₂O₄) for the rapid, sensitive, and accurate detection of MG-related acetylcholine receptors (AChR) antibodies. Comprehensive characterization by Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) confirmed the successful fabrication and structural integrity of the sensor. Differential pulse voltammetry (DPV) measurements revealed a broad linear detection range (10 pg/mL to 100 µg/mL) and an ultra-low detection limit of 10 pg/mL. The sensor demonstrated excellent selectivity, reproducibility, repeatability, and stability. Recovery studies with human serum yielded high recoveries (90%-110%) with low relative standard deviation (RSD) (0.277%-0.482%). Furthermore, preliminary clinical testing showed the immunosensor could reliably distinguish MG patient samples from healthy controls, supporting its practical diagnostic utility. Overall, these results highlight the sensor's strong potential as a rapid, reliable, and cost-effective tool for MG diagnosis in clinical and point-of-care applications.