Ultra-sensitive GO–MoS₂/AuNPs hybrid biosensor for early-stage age-related macular degeneration via complement component C3 detection

Abstract Age-related macular degeneration (AMD) is a leading cause of vision loss, where early diagnosis remains critical for effective intervention. Complement component 3 (C3) plays a vital role in AMD pathogenesis, making it a promising biomarker for early-stage detection. In this study, we report an electrochemical immunosensor based on a Graphene oxide–Molybdenum disulfide/Gold nanoparticles (GO–MoS₂/AuNPs) hybrid nanocomposite for the ultrasensitive detection of C3 in tear samples via a non-invasive approach. The GO–MoS₂ platform provides a high surface area with abundant functional groups for efficient antibody immobilization, while AuNPs enhance electron transfer and signal amplification. The sensor response was evaluated using electrochemical impedance spectroscopy, where antigen–antibody interactions modulate charge transfer resistance ( R _ct ). The developed biosensor exhibits a wide linear detection range from 10 fg ml ⁻¹ (1 × 10 ⁻⁸ ppm) to 500 pg ml ⁻¹ (5 × 10 ⁻⁴ ppm) and an ultralow theoretical limit of detection (LOD) of 1.17 fg ml ⁻¹ , calculated using the formula 3.3 σ /slope. Additionally, a high sensitivity of 518.05% (Δ R _ct / R _ct ) (g ml ⁻¹ ) ⁻¹ cm ⁻² was achieved, indicating efficient signal transduction. These results demonstrate the strong potential of the proposed platform for rapid, sensitive, and non-invasive detection of C3, offering a promising strategy for early AMD diagnosis.