DESIGN, SYNTHESIS AND APPLICATION OF NOVEL 1D AND 2D-NANOCOMPOSITES FOR BIOSENSING

Electrochemical sensors and biosensors are self-contained integrated devices that enable getting quantitative information on the concentration of biomolecules of interest in real time, with high sensitivity. Advance in electrochemical sensing technology is beneficial for several applications, from the detection of pollutants in environmental matrices to point-of-care testing and clinical analysis, to food safety. The development of new electrocatalytic materials and nanostructured electrodes has greatly fostered electrochemical sensors. Electroactive nanomaterials, like carbon nanotubes, metal nanoparticles, graphene, and other 2D materials, can boost the performances of electrochemical sensors, by enhancing the total contact surface area, improving charge transfer, and catalyzing redox processes involved in the sensing mechanism. The objective of this thesis is to develop novel 1D and 2D nanomaterials and nanocomposites to implement in electrochemical sensing platforms for biomolecules of interest, as electrocatalysts. The properties of the used nanomaterials have been tuned by different approaches, involving functionalization of their surface, phase engineering, and optimization of synthetic strategies, to improve their performance in terms of electrocatalytic activity, sensitivity, selectivity, and conductivity. Specifically, the first chapter will focus on the modification of Multiwalled Carbon Nanotubes (MWCNTs) with gold nanoparticles (AuNPs) from metal vapor synthesis (MVS) for the detection of monoamine neurotransmitters like dopamine and serotonin. The obtained nanocomposite (MWCNT-S-Au) was then implemented in a sensor based on screen-printed carbon electrodes (SPCE) for sensing of serotonin in complex biological matrices and in an indium tin oxide (ITO) electrode for in situ real-time detection of neurotransmitters in neuronal cultures. The second chapter revolves around phase engineering and functionalization of molybdenum disulfide (MoS2) for the detection of hydrogen peroxide (H2O2). In this case, attention was focused on the influence of different crystalline phases on the electrocatalytic properties of the material and the design of a functionalization strategy based on non-covalent interactions with alkylammonium salts. Finally, the third chapter describes a study on the exfoliation of graphene in Cyrene, a green alternative to commonly used DMF and NMP. In this study, we observed the effect of experimental and instrumental parameters for ultrasound-assisted exfoliation of graphene from graphite, to find optimal conditions for exfoliation of few-layer graphene nanosheets.