Nanostructured thin films as electrochemical sensors and biosensors for milk analysis

During the last decade, nanomaterials and supramolecular assemblies have received considerable attention in different fields of sensing applications. The interest of supramolecular assemblies arises from the exceptional performances of nanostructured films based on such assemblies, which are related to both their well-controlled structure and their large surface area. These characteristics increase the number of active sites and facilitate the charge transport pathways. In addition, supramolecular assemblies can be used to prepare multicomponent sensing layers formed by materials with complementary activity. Finally, supramolecular films are highly efficient platforms for enzyme immobilization leading to highly sensitive biosensing.

This paper describes the main concepts and approaches related to the development of supramolecular sensing layers in electrochemical sensors and biosensors. Different techniques commonly employed to develop supramolecular sensing layers, such as Self-assembling, Layer-by-layer and Langmuir-Blodgett, are described and their role as electron mediators in biosensors is revised using milk as an example of the target analyte. Using this approach, enzymes are immobilized in a biomimetic environment, giving rise to efficient biosensors able to detect glucose, galactose or lactose in milk with high degree of selectivity and low limits of detection.

We also include a brief discussion of the possibilities of the integration of supramolecular assemblies into sensor arrays as the core of electronic and bioelectronic tongues. The advantages of these systems are related to their fast responses and their capability to detect many components in a single measurement. The expected limitations mainly related to the fouling of the electrodes, are also discussed.