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

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 central 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 nanoparticle (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 (Rct). The developed biosensor exhibits a wide linear detection range from 10 fg mL⁻¹ (1 x10-8 ppm) to 500 pg mL⁻¹ (5 x 10-4 ppm) and an ultralow theoretical limit of detection of 1.17 fg mL⁻¹, calculated using the 3.3σ/slope method. Additionally, a high sensitivity of 518.05 % (ΔRct/Rct) (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.