Evaluation of oxidative stress: Nanoparticle-based electrochemical sensors for hydrogen peroxide determination in human semen samples.

We have developed electrochemical sensors for the determination of H2O2 in a complex matrix such as human semen as a method to evaluate oxidative stress related to male infertility. Our sensors are based on the modification of conventional electrode surfaces with nanoparticles. We used diamond nanoparticles (DNp) either on glassy carbon or gold surfaces (GC/DNp and Au/DNp sensors, respectively), and copper nanoparticles electrochemically generated directly on glassy carbon surfaces (GC/CuNp). The morphology of the modified electrode surfaces was characterized by Atomic Force Microscopy (AFM), and the H2O2 determination performance evaluated by chronoamperometric measurements at different applied potentials. The best results are obtained for GC/DNp at +1.0 V, Au/DNp at -0.6 V and GC/CuNp at +0.2 V with detection limits (LD) of 1.1 μM, 2.4 μM and 2.6 μM, respectively. The analysis of H2O2 in doped synthetic semen using the GC/CuNp sensor shows the best recoveries, reaching a mean value of 103%. The GC/CuNp sensor was successfully applied to H2O2 analysis in real human semen. In this case, a H2O2 concentration of 1.42 ± 0.05 mM is found and recoveries of 102% on average are obtained.