Disposable electrochemical immunosensor for Brettanomyces bruxellensis based on nanogold-reduced graphene oxide hybrid nanomaterial

Development of a molecular diagnostic test for the specific detection of Brettanomyces bruxellensis in red wine

Brettanomyces bruxellensis is considered the main source of spoilage in red wine. This yeast, by producing volatile phenols, is responsible for the development of unpleasant aromas affecting the quality of final products and resulting in substantial economic losses for wine producers. This work therefore describes the development of an easy to-use colorimetric molecular diagnostic test for the rapid and specific detection of B. bruxellensis in wine. Detection was achieved using a sandwich hybridization format in which the target RNA was recognized by an immobilized DNA capture probe and a labelled DNA signal probe. The proposed device was highly specific to B. bruxellensis and showed a linear relationship between measured signal and target RNA concentration in the range 0.1-5 ng μL-1, with a limit of detection value of 0.1 ng μL-1 of total RNA. The colorimetric assay was validated on red wine samples, with a detection limit of 102 CFU mL-1. This study suggests that the reported method could be used for early detection of spoilage yeasts in wine and other alcoholic beverages.

Application of Electrochemical Biosensors for Determination of Food Spoilage

Food security is significantly affected by the mass production of agricultural produce and goods, the growing number of imported foods, and new eating and consumption habits. These changed circumstances bring food safety issues arising from food spoilage to the fore, making food safety control essential. Simple and fast screening methods have been developed to detect pathogens and biomarkers indicating the freshness of food for safety. In addition to the traditional, sequential, chemical analytical and microbiological methods, fast, highly sensitive, automated methods suitable for serial tests have appeared. At the same time, biosensor research is also developing dynamically worldwide, both in terms of the analytes to be determined and the technical toolkit. Consequently, the rapid development of biosensors, including electrochemical-based biosensors, has led to significant advantages in the quantitative detection and screening of food contaminants. These techniques show great specificity for the biomarkers tested and provide adequate analytical accuracy even in complex food matrices. In our review article, we summarize, in separate chapters, the electrochemical biosensors developed for the most important food groups and the food safety issues they can ensure, with particular respect to meat and fish products, milk and dairy products, as well as alcoholic and non-alcoholic beverages.

Nanoarchitectonics of graphene based sensors for food safety monitoring

Since the desire for the real-time food quality monitoring, plenty of research effort has been made to develop novel tools and to offer extremely efficient detection of food contaminants. Unique electrical, mechanical, and thermal properties make graphene an important material in the field of sensor research. The material can be manufactured into flakes, sheets, films and with its oxidized derivatives could be almost used for a limitless set of application. Herein, current graphene-based sensors for food quality monitoring, novel designs, sensing mechanisms and elements of sensor systems and potential challenges will be outlined and discussed.

Electrochemical Affinity Biosensors Based on Selected Nanostructures for Food and Environmental Monitoring

The excellent capabilities demonstrated over the last few years by electrochemical affinity biosensors should be largely attributed to their coupling with particular nanostructures including dendrimers, DNA-based nanoskeletons, molecular imprinted polymers, metal-organic frameworks, nanozymes and magnetic and mesoporous silica nanoparticles. This review article aims to give, by highlighting representative methods reported in the last 5 years, an updated and general overview of the main improvements that the use of such well-ordered nanomaterials as electrode modifiers or advanced labels confer to electrochemical affinity biosensors in terms of sensitivity, selectivity, stability, conductivity and biocompatibility focused on food and environmental applications, less covered in the literature than clinics. A wide variety of bioreceptors (antibodies, DNAs, aptamers, lectins, mast cells, DNAzymes), affinity reactions (single, sandwich, competitive and displacement) and detection strategies (label-free or label-based using mainly natural but also artificial enzymes), whose performance is substantially improved when used in conjunction with nanostructured systems, are critically discussed together with the great diversity of molecular targets that nanostructured affinity biosensors are able to quantify using quite simple protocols in a wide variety of matrices and with the sensitivity required by legislation. The large number of possibilities and the versatility of these approaches, the main challenges to face in order to achieve other pursued capabilities (development of antifouling, continuous operation, wash-, calibration- and reagents-free devices, regulatory or Association of Official Analytical Chemists, AOAC, approval) and decisive future actions to achieve the commercialization and acceptance of these devices in our daily routine are also noted at the end.

Disposable amperometric immunosensor for Saccharomyces cerevisiae based on carboxylated graphene oxide-modified electrodes

A sensitive and disposable amperometric immunosensor for Saccharomyces cerevisiae was constructed by using carbon screen-printed electrodes modified with propionic acid-functionalized graphene oxide as transduction element. The affinity-based biosensing interface was assembled by covalent immobilization of a specific polyclonal antibody on the carboxylate-enriched electrode surface via a water-soluble carbodiimide/N-hydroxysuccinimide coupling approach. A concanavalin A-peroxidase conjugate was further used as signaling element. The immunosensor allowed the amperometric detection of the yeast in buffer solution and white wine samples in the range of 10-10⁷ CFU/mL. This electroanalytical device also exhibited low detection limit and high selectivity, reproducibility, and storage stability. The immunosensor was successfully validated in spiked white wine samples.