3-Nitrotyrosine (3-NT) results from the nitration mediated by reactive nitrogen species such as peroxynitrite anion and nitrogen dioxide. It is overproduced when there is oxidative stress in the body, which is an imbalance of free radicals and antioxidants within the body. Oxidative stress is common in many diseases like cancer and heart disease. 3-NT has been identified as a biomarker for cell damage, inflammation, as well as nitric oxide production. Therefore, its monitoring is important for disease monitoring.  An electrochemical biosensor platform was prepared by modifying a gold electrode with N-hydroxysuccinimide (NHS) ester gold nanoparticles.  The NHS ester gold nanoparticles created a monolayer on the electrode surface which was used to covalently immobilize 3-NT antibodies. The modified electrode surface was then used for the detection of 3-NT using cyclic voltammetry and differential pulse voltammetry. The detection method was very sensitive to 3-Nitrotyrosine with a linear response from 50 to 600 nM concentrations. Future research will involve testing the selectivity, and stability of the method as well as testing real biological samples such as urine, serum, and saliva for potential practical applications.