Herein, we demonstrate the use of lysozyme (Lys) as a model to fabricate a protein carrier system based on gold nanoparticles (AuNPs) via the Layer-by-Layer (LbL) technology. Poly(ethyleneimine) (PEI) and poly(sodium 4-styrenesulfonate) (PSS) were used as cationic and anionic polymers respectively to grow oppositely charged layers. Mild aqueous conditions were utilized to avoid protein denaturation and activity instead of organic solvents that have been used in other encapsulation systems. Two different strategies were used: (A) lysozyme acting as a reducing and stabilizing agent in the formation of AuNPs at a temperature of 45 ± 2 °C followed by only two subsequent polymeric layers deposited by LbL, and (B) citrate acting as a reducing agent prior to stabilization of the AuNPs by mercaptoundecanoic acid. Dynamic light scattering, UV-vis spectroscopy, IR spectroscopy and transmission electron microscopy were used to characterize the nanoconjugates. Furthermore, the enzymatic activity of the resulting protein/nanoparticle conjugates was evaluated using the bacteria Micrococcus lysodeikticus as a substrate.

The electronic tongue (ET) and bioelectronic tongue (bioET) technologies have emerged as innovative and promising tools for the characterization and quality control of complex liquid matrices such as grape musts and wines. These multisensor systems, based on electrochemical detection and chemometric analysis, provide global and rapid information about taste-related attributes, antioxidant content, and other critical parameters, offering an alternative or complement to traditional analytical methods. This review explores the principles, development, and applications of ET and bioET in the wine industry, highlighting their capacity to assess grape ripeness, monitor fermentation, determine wine aging, detect adulterations, and support geographical and varietal authentication. Special attention is paid to advances in sensing materials—such as conducting polymers, metal nanoparticles, and enzymes—and the construction techniques of sensors and biosensors, which have improved ET performance. Finally, the potential of these technologies as cost-effective, portable, and on-site tools aligns with the demands of Industry 4.0 and next-generation smart agriculture and food production systems.