Sustainable Drug Delivery Solutions and Sensing Technologies for Nutrition and Health

This thesis investigates the development and application of advanced systems based on sustainable biopolymers, specifically sericin and zein, addressing interconnected challenges in nutraceutical delivery and electrochemical biosensing. The research leverages the principles of the circular economy by valorizing sericin, a protein byproduct from the silk industry, and zein, an abundant co-product from corn processing, as functional materials for high-value applications. The first research axis focused on fabricating a scalable, food-grade delivery system for the lipophilic micronutrient Vitamin A for the animal feed sector. Nanostructured Lipid Carriers (NLCs), formulated via a solvent-free melt-emulsification method, were successfully coated with sericin. A critical finding was the system's inherent instability at the industry-relevant benchmark of pH 4,5. This challenge was definitively overcome by developing a post-processing cold-crystallization treatment, which induced an irreversible conformational transition in the sericin shell from a random coil to a highly stable β-sheet structure. This structural modification rendered the NLC-Ser system colloidally stable in acidic conditions. The platform's robustness was validated by a three-year long-term stability study, where FTIR analysis confirmed the encapsulated VA remained chemically intact. The second research pillar addressed the encapsulation of the hydrophilic Vitamin B12 within electrospun zein structures, targeting the fortification of vegan-compliant, plant-based beverages. Process optimization revealed that zein concentration was the paramount parameter governing fiber morphology, with 25% w/v zein yielding stable, bead-free fibers. A key validation was the system's exceptional thermal robustness; kinetic analysis via the Friedman method confirmed the degradation onset remains well above 280°C, demonstrating suitability for industrial UHT pasteurization. However, this study also identified the system's primary limitation: the immediate hydrophobic collapse of the fibers in water, leading to payload leaching. The third research axis interconnected these themes by developing electrochemical sensing strategies for both quality control and diagnostics. A proof-of-concept for quantifying encapsulated payloads was established using a synthesized Ferrocene-Schi􀆯 Base proxy, which was successfully detected within zein nanoparticles in a dose-dependent manner. This work then demonstrated the multifunctionality of sericin, transitioning it from a passive coating to an active bioelectronic component. A novel, printable TEGO:Ser conductive ink was formulated, proving sericin to be a superior and sustainable binder and dispersant. The resulting ink exhibited a 7-fold increase in electrical conductivity and a significantly higher electroactive surface area (66.9%) compared to conventional formulations. This highperformance material was successfully integrated as the transducer for an electrochemical immunosensor for cortisol. The sensor demonstrated excellent analytical performance, fitting a biphasic linear model across the physiological range (Adj. R² > 0.99 for the high-sensitivity regime) and achieving a Limit of Detection of 67.6 pM by CV. Furthermore, the superior sensitivity of EIS as a transduction method was established, enabling detection at the 2.76 pM (1 pg/mL) level. Finally, the study identified that while the sensor possesses excellent inherent selectivity, its primary vulnerability is a pronounced signal suppression (up to 90%) due to matrix e􀆯ects from biofouling, defining a critical challenge for future anti-fouling surface engineering.