MoS₂-supported multiepitope protein electrochemical biosensors: A simple and highly selective approach for the...

Cryptococcosis is a life-threatening fungal infection with global public health impact, affecting both immunocompromised individuals and the general population. Accurate clinical management requires differentiation of Cryptococcus species and detection of subclinical infections. However, current diagnostic methods suffer from limited sensitivity and, notably, selectivity. Here, we report a highly sensitive and selective electrochemical immunosensor for rapid and simple serological diagnosis of cryptococcosis. The sensor employs novel multi-epitope chimeric proteins (A, B, C, and D) directly anchored onto a molybdenum disulfide (MoS₂)-functionalized gold electrode, enabling simplified construction and stable bioreceptor immobilization without chemical cross-linkers. Comprehensive physicochemical characterization by SPR, AFM, EDS, SEM, Raman spectroscopy, and electrochemical techniques provided essential structural information governing the synergistic integration of MoS₂ and chimeric proteins. Using Square Wave Voltammetry (SWV), a comparative evaluation against human serum samples identified Protein D as the main bioreceptor, providing the highest discrimination between positive and negative groups. The optimized MoS₂/Protein D immunosensor achieved an outstanding limit of detection (LOD) of 0.124 fmol L^-1 and a wide linear range spanning from fmol L^-1 to nmol L^-1. Clinical validation via ROC curve analysis demonstrated excellent diagnostic performance, with 100% sensitivity, 87.5% specificity, and an area under the curve (AUC) of 0.987. Furthermore, the sensor exhibited high selectivity against a panel of five other systemic mycoses (aspergillosis, histoplasmosis, sporotrichosis, coccidioidomycosis, and paracoccidioidomycosis), overcoming the specificity gaps of routine assays. These results represent a significant advance for clinical practice and highlight the potential of simple electrochemical approaches to resolve complex diagnostic problems.