Different Approaches in Designing Sensitive Tools Based on Nanocomposite Materials for Biological Analytes Detection ^†

Sensitive, stable and robust electrochemical sensors have been designed through modification of the working electrodes with different complex matrices based on carbon nanomaterials and metallic nanoparticles. Therefore, screen-printed electrodes were modified with complex matrices of hybrid nanomaterials using physical deposition or entrapment in polymeric film. The designed sensors allowed a fast and sensitive detection of some important biological analytes involved in the degradation process of several food products [1], as well as in the electrocatalytic activity toward oxidation of some phenolic compounds found to be environmental pollutants [2]. Electrochemical sensitive platforms have been designed by modification of the carbon screen-printed electrodes with a hybrid nanocomposite matrix, through entrapment into a polymeric film of 2,6-dihydroxinaphtalene and 2-(4-aminophenyl)-ethylamine. The functionalization of carbon nanomaterials with metallic nanoparticles leads to obtaining multifunctional materials with uniform structures and improved electrocatalytic behavior, allowing the acceleration of the electron transfer to the electrode surface and further sensitive detection of the analyte of interest. The functionalized sensors were characterized by electrochemical studies and the kinetics of the electron transfer were investigated by electrochemical impedance spectroscopy, while the morphology of the surface was determined by SEM, TEM and FTIR spectroscopy. The FTIR spectroscopy studies showed that a dispersion of carbon nanomaterials and metallic nanoparticles into the polymeric matrix leads to the formation of a stable film. The electron transfer resistance recorded for unmodified and modified sensors revealed that the presence of carbon nanomaterials together with platinum nanoparticles considerably decreases the resistance to electron transfer. This decrease shows that the nanocomposite materials pose high conductivity, accelerating the electron transfer and demonstrating the synergy of the materials used and the increase in the electrocatalytic capacity of the sensor surface. Further, amperometric detection of hydrogen peroxide has been performed at an applied working potential of +0.15 V vs. Ag/AgCl, in a concentration range of 0.01 to 5 mM. The modification of sensors with hybrid nanomaterials provides an electroconductive network and a large active surface of the sensors, thus accelerating the transfer of electrons, allowing a sensitive detection of some biological analytes without the need of a bioreceptor.