"Immunoassays are nowadays a crucial tool for diagnostics, drug development, and environmental monitoring. However, most immunoassay methods involve cumbersome procedures such as washing, blocking, or separation steps, and in general, require many bioreagents for their operation. In this thesis, a single-step immunosensing platform based on the fluorescence quenching capability of graphene oxide (GO) and the versatile format offered by the famous 96 microwell plates was developed. This approach was used for the detection of clinically relevant proteins such as Human immunoglobulin G (H-IgG), Prostate Specific Antigen (PSA), and Heat Shock Protein 72 (Hsp72)."