Development of biosensors for clinical and food-safety control

In the last two years, the COVID-19 pandemic affected every aspect of our daily routines, unprecedentedly changing our quality of life and lifestyle trends. As a result of this tragic event, great attention is being paid to promptly prevent the uncontrolled spread of pathogens and, in general, to implement quality control for human safety. In particular, several tools were developed in order to monitor the presence of toxins, viruses or disease biomarkers’ in clinical, environmental and food safety fields. In this regard, electrochemical or optical sensors represent a valid alternative to traditional techniques such as chromatography or spectroscopy, being more effective than the latter, which in any case require a minimum of in-presence sample processing and high employment of reagents and time. Recently, electrochemical sensors have played, in particular, a pivotal role in detecting and quantifying dangerous compounds, which is essential in industries like medical diagnostics and environmental monitoring. These devices are the most used due to their high-performance, small size, portability, and easy-to-use sensing platforms. Currently, screen-printing technology is one of the most established techniques for the mass production of electrochemical sensors with good sensitivity, selectivity, and repeatability. Since the 1990s, this technique has offered highvolume production of inexpensive, dependable sensors, which has paved the way for on-site monitoring and analysis of various chemicals using portable instruments in several applications such as clinical, environmental and food-testing fields. Moreover, with the continuous progress in material science technology, the understanding of carbon-based materials properties has reached a new level of interest. In recent years, carbon nanomaterials have been increasingly used in sensors production, either as transducers (due to their unique optical, chemical, electrical and catalytic properties) or as components of the recognition element of a biosensing device (due to the high surface-to-volume ratio that increases the bioreceptor’s loading on the sensing surface). This thesis is focused on different strategies for the development of electrochemical biosensors, both enzymatic and immunological, applicable in the clinical and food safety field. In particular, the electrochemical performance of nanomaterials-based sensing platforms has been carefully studied, and an alternative pyrolytic ecofriendly carbonaceous material, named biochar, has been proposed. Furthermore, a new configuration of the screen-printed electrode (named inverse-designed screenprinted electrode), and an innovative label-free approach for food (ochratoxin A and aflatoxin B1) and clinical (interleukin-6) analysis have been proposed. This dissertation is divided into three fundamental building blocks.