Bioelectronic Tongues Research Articles

Bioelectronic Tongue for Identifying and Masking Bitterness Based on Bitter Taste Receptor Agonism and Antagonism

AbstractBitterness elicits unpleasant sensations in humans, which can hinder the acceptance of foods and medication adherence. Therefore, identifying and masking bitter tastes is crucial for developing palatable foods and promoting medication compliance in the food and pharmaceutical industries. To achieve this, employing agonism and antagonism of bitter taste receptors as effective strategies at the molecular level is essential. In this study, a bioelectronic tongue is developed to characterize the agonism and antagonism of bitter taste receptors. The human bitter taste receptors hTAS2R16 and hTAS2R31 are produced using an Escherichia coli expression system and reconstituted into nanodiscs (NDs). Subsequently, hTAS2R16‐ and hTAS2R31‐NDs are immobilized on the surface of graphene field‐effect transistors (FETs) to construct bioelectronic tongues. The developed system sensitively detected the bitter agonists, salicin and saccharin, at concentrations as low as 100 fM, with high selectivity in real‐time. The dose‐dependent curves shifted and K values decreased by the antagonists of hTAS2R16 and hTAS2R31, indicating antagonism‐based masking of bitter taste. Therefore, the developed bioelectronic tongue holds promise for identifying bitter tastes and evaluating the masking of bitterness based on the agonism and antagonism of hTAS2Rs.

Enhancing the Capabilities of Electrochemical Sensor Arrays Using Nanomaterials and Nanostructured Films

In the last years electronic tongues (ET) based on electrochemical sensors coupled to a pattern recognition system, have been developed and applied to the analysis of a variety of foods [1]. Nowadays it is evident that improvements in the field involve the development of instruments dedicated to a specific application. This requires the search of sensors specifically designed to analyze an specific target, using the appropriate sensing materials and transduction methods adapted to a specific problem.Important advances in the field of electrochemical sensors are linked to the use of techniques and materials coming from the field of nanoscience. On one hand, incorporating nanomaterials in the sensing layers can enhance the sensitivity thanks to their excellent electrocatalytic properties. On the other hand, using nanostructured sensing layers can offer opportunities to increase the number of active sites at the surface and to develop structures similar to that of the cellular membranes that can host enzymes or other biologic receptors in a biomimetic environment. Here, the new strategies based on potentiometric and voltammetric sensors will be presented, paying special attention to the new developments based on nanobiosensors and the combinations of enzymes with nanomaterials.The developments of our group in the field of multisensor systems based on potentiometric sensors and biosensors applied to the analysis of milk are based on PVC membranes where different additives and plasticizers are added. The different compositions give rise to membranes with different porosity and hydrophilicity and hence an array of sensors with cross-sensitivity can be constructed. Such an array can discriminate main components of milk such as galactose, lactose, lactic acid or urea. The capability of the array is drastically enhanced when the membranes are modified with combinations of nanoparticles and enzymes specific to components present in milk such as galactose oxydase, lactose dehydrogenase or urease [2].Voltammetric sensors can be used to analyze liquid mixtures containing electroactive substances. The example shown here is the wine, which is an hydroalcoholic solution rich in antioxidants such as the polyphenols and sugars such as glucose.In arrays of voltammetric sensors, electrodes are chemically modified with electrocatalytic materials that increase the intensity of the signals while reducing the oxidation potential of the phenols. Classic materials such as phthalocyanines or conducting polymers are excellent electrocatalytic materials that facilitate the electron transfer between the phenols or sugars and the electrode. Metal nanoparticles and nanocarbons are also excellent electron mediators [3].Nanostructured Sensing layers prepared using de Layer by Layer (LbL) or the Langmuir-Blodgett (LB) technique can further increase the intensity of the signals due to the high surface-to-volume ratio. In addition, these techniques facilitate the preparation of films made of different materials with different functionalities. For instance, the combination of nanoparticles with phthalocyanines have synergistic effects that increase even further the intensity of the signals.Enzymes such as glucose oxydase or galactose oxydase (specific for the detection of sugars) or tyrosinase or laccase (specific for the detection of phenols) have been introduced in nanostructured films based on phospholipids that create a biomimetic environment enhancing the performance of the sensors.The biosensors described above have been combined to develop bioelectronic tongues (bio-ETs) that have been successfully used to discriminate and classify milk and wine samples. References Rodríguez-Méndez, M.L., Electronic noses and tongues in the food industry. Elsevier-Academic press, 2016 Perez-Gonzalez et al., Food Control, 145, 109425 (2023) Medina-Plaza et. Al. Biosens. Bioelectronics, 57, 276-286 (2015)

Hydrogel-based Bioelectronic Tongue for the Evaluation of Umami Taste in Fermented Fish.

Bioelectronic tongues based on umami taste receptors have recently been reported for versatile applications such as food analyses. However, their practical applications are still limited, partly due to their limited stability and non-specific responses in real sample environments. Herein, we have developed a hydrogel-based bioelectronic tongue for the sensitive assessment of umami intensity in fish extract samples. In this study, the T1R1 venus flytrap of an umami taste receptor was immobilized on the gold floating electrodes of a carbon nanotube-based field-effect transistor. A polyacrylamide conducting hydrogel film was further hybridized on the sensor surface via physical adsorption, which could provide a good physiological environment to maintain the activity of receptors due to its excellent hydrophilicity and biocompatibility. The bioelectronic tongue with a receptor-embedded hydrogel structure showed a sensitive detection of umami substances down to 1 fM, and it also had a wide detection range of 10-15-10-2 M for monosodium glutamate and disodium inosinate, which covers the human taste threshold. More importantly, the proposed sensor could significantly reduce the non-specific binding of non-target molecules to a carbon nanotube channel as well as exhibit long-term stability, enabling sensitive detection of umami substances even in fish extract samples. Our hydrogel-based bioelectronic tongue provides a promising platform for future applications such as the flavor evaluation of foods and beverages.

Bioelectronic tongue dedicated to the analysis of milk using enzymes linked to carboxylated-PVC membranes modified with gold nanoparticles

Bioelectronic tongues (bioET) made of sensors combining enzymes and nanomaterials have been shown to be advantageous due to the specificity offered by the biosensors and the enhanced sensitivity provided by the nanomaterials. In this work, an innovative bioET for milk analysis is developed using potentiometric biosensors based on lactic dehydrogenase, galactose oxidase and urease specific for the detection of compounds of interest in milk (lactic acid, galactose and urea). The performance of the biosensors has been fostered by covalently immobilizing the enzymes on membranes of carboxylated polyvinyl chloride combined with gold nanoparticles. The design and composition of the biosensors contributes to preserving the enzymatic activity, allowing limits of detection in the range of 10 −5 – 10 −6 M with excellent sensitivity and reproducibility (variation coefficients ranged from 1 to 5.1%). The three biosensors, combined in a single device and coupled to a pattern recognition software, can discriminate efficiently twelve classes of milk with different fat content (skimmed, semi-skimmed and whole milk) and nutritional characteristics (calcium enriched, lactose free and folic acid-enriched). The bioET shows an excellent classification capability with an accuracy of up to 99.7%. By applying Support Vector Machine (SVM) analysis, the BioET can perform the simultaneous assessment of eight physicochemical parameters (acidity, fat, proteins, lactose, density, urea, dry matter and nonfat dry matter) with satisfactory correlation coefficients and low residual errors. The results are further improved by implementing ensemble methodologies. The proposed strategy has been demonstrated to be useful for improving the performance of bioETs in the dairy industry. • A potentiometric bioET specifically dedicated to milk analysis was developed. • Enzymes were covalently linked to membranes combining Carboxilated-PVC and AuNPs. • The effective enzymatic immobilization helped to retain the enzymatic activity. • Using SVM and ensemble methods, nine physicochemical parameters can be determined simultaneously.

All-in-one terahertz taste sensor: integrated electronic and bioelectronic tongues

All-in-one terahertz taste sensor: integrated electronic and bioelectronic tongues with a multiarray of bioreceptors and sensing materials.

Bioelectronic Tongues Mimicking Insect Taste Systems for Real-Time Discrimination between Natural and Artificial Sweeteners.

A bioelectronic tongue (B-ET) mimicking insect taste systems is developed for the real-time detection and discrimination of natural and artificial sweeteners. Here, a carbon nanotube field-effect transistor (CNT-FET) was hybridized with nanovesicles including the honeybee sugar taste receptor, gustatory receptor 1 of Apis mellifera (AmGr1). This strategy allowed us to detect glucose, a major component of nectar, down to 100 fM in real time and identify sweet tastants from other tastants. It could also be utilized for the detection of glucose in dextrose tablet solutions. Importantly, we demonstrated the discrimination between natural and artificial sweeteners down to 10 pM even in real beverages such as decaffeinated coffee using our hybrid platform. In this respect, our B-ET mimicking insect taste systems can be a powerful tool for various applications such as food screening and basic studies on insect taste systems.

A novel umami electrochemical biosensor based on AuNPs@ZIF-8/Ti3C2 MXene immobilized T1R1-VFT

The bioelectronic tongues based on taste receptors have been emerging with human-like taste perception. However, the practical applications of the receptor-based biosensors were restricted by their narrow and low dynamic ranges. Here, a novel immobilization strategy based on AuNPs@ZIF-8/Ti3C2 MXene was developed to immobilize the umami ligand binding domain (T1R1-VFT), to fabricate an umami biosensor for umami substances detection. Through the synergic effect of AuNPs@ZIF-8 and Ti3C2 MXene, the capacity to load T1R1-VFT was effectively increased, and the response signal was also amplified by approximately 3 times. The proposed biosensor showed an ultrawide dynamic range of 10−11–10−3 M, and a high upper limit of detection, which was closer to the human taste threshold and suitable for detecting foods rich in umami substances. Additionally, the biosensor was successfully applied to detect real samples and analyze the synergistic effects of binary umami substances.

A novel bionic in vitro bioelectronic tongue based on cardiomyocytes and microelectrode array for bitter and umami detection

Electronic tongues (ETs) have been developed and widely used in food, beverage and pharmaceutical fields, but limited in sensitivity and specificity. In recent years, bioelectronic tongues (BioETs) integrating biological materials and various types of transducers are proposed to bridge the gap between ET system and biological taste. In this work, a bionic in vitro cell-based BioET is developed for bitter and umami detection, utilizing rat cardiomyocytes as a primary taste sensing element and microelectrode arrays (MEAs) as a secondary transducer for the first time. The primary cardiomyocytes of Sprague Dawley (SD) rats, which endogenously express bitter and umami taste receptors, were cultured on MEAs. Cells attached and grew well on the sensor surface, and syncytium was formed for potential conduction and mechanical beating, indicating the good biocompatibility of surface coating. The specificity of this BioET was verified by testing different tastants and bitter compounds. The results show that the BioET responds to bitter and umami compounds specifically among five basic tastants. For bitter recognition, only those can activate receptors in cardiomyocytes can be recognized by the BioET, and different bitter substances could be discriminated by principal component analysis (PCA). Moreover, the specific detections of two bitters (Denatonium Benzoate, Diphenidol) and an umami compound (Monosodium Glutamate) were realized with a detection limit of 10−6 M. The cardiomyocytes-based BioET proposed in this work provides a new approach for the construction of BioETs and has promising applications in taste detection and pharmaceutical study.

High-performance bioelectronic tongue using ligand binding domain T1R1 VFT for umami taste detection

Numerous efforts have been made to measure tastes for various purposes. However, most taste information is still obtained by human sensory evaluation. It is difficult to quantify a degree of taste or establish taste standard. Although artificial taste sensors called electronic tongues utilizing synthetic materials such as polymers, semiconductors, or lipid membranes have been developed, they have limited performance due to their low sensitivity and specificity. Recently, bioelectronic tongues fabricated by integrating human taste receptors and nanomaterial-based sensor platforms have been found to have high performance for measuring tastes with human-like taste perception. However, human umami taste receptor is heterodimeric class C GPCR composed of human taste receptor type 1 member 1 (T1R1) and member 3 (T1R3). Such complicated structure makes it difficult to fabricate bioelectronic tongue. The objective of this study was to develop a protein-based bioelectronic tongue for detecting and discriminating umami taste with human-like performance using umami ligand binding domain called venus flytrap (VFT) domain originating from T1R1 instead of using the whole heterodimeric complex of receptors. Such T1R1 VFT was produced from Escherichia coli (E. coli) with purification and refolding process. It was then immobilized onto graphene-based FET. This bioelectronic tongue for umami taste (BTUT) was able to detect monosodium L-glutamate (MSG) with high sensitivity (ca. 1 nM) and specificity in real-time. The intensity of umami taste was enhanced by inosine monophosphate (IMP) that is very similar to the human taste system. In addition, BTUT allowed efficient reusable property and storage stability. It maintained 90% of normalized signal intensity for five weeks. To develop bioelectronic tongue, this approach using the ligand binding domain of human taste receptor rather than the whole heterodimeric GPCRs has advantages in mass production, reusability, and stability. It also has great potential for various industrial applications such as food, beverage, and pharmaceutical fields.

A novel bioelectronic tongue in vivo for highly sensitive bitterness detection with brain–machine interface

Animals' gustatory system has been widely acknowledged as one of the most sensitive chemosensing systems, especially for its ability to detect bitterness. Since bitterness usually symbolizes inedibility, the potential to use rodent's gustatory system is investigated to detect bitter compounds. In this work, the extracellular potentials of a group of neurons are recorded by chronically coupling microelectrode array to rat's gustatory cortex with brain–machine interface (BMI) technology. Local field potentials (LFPs), which represent the electrophysiological activity of neural networks, are chosen as target signals due to stable response patterns across trials and are further divided into different oscillations. As a result, different taste qualities yield quality-specific LFPs in time domain which suggests the selectivity of this in vivo bioelectronic tongue. Meanwhile, more quantitative study in frequency domain indicates that the post-stimulation power of beta and low gamma oscillations shows dependence with concentrations of denatonium benzoate, a prototypical bitter compound, and the limit of detection is deduced to be 0.076μM, which is two orders lower than previous in vitro bioelectronic tongues and conventional electronic tongues. According to the results, this in vivo bioelectronic tongue in combination with BMI presents a promising method in highly sensitive bitterness detection and is supposed to provide new platform in measuring bitterness degree.

The advantages of disposable screen-printed biosensors in a bioelectronic tongue for the analysis of grapes

Disposable screen-printed sensors have been modified with enzymes and used to form a bioelectronic tongue dedicated to the discrimination between different grape varieties. The multisensory system combined serigraphied electrodes modified with carbon, platinum, gold, graphene, Prussian blue and nickel oxide nanoparticles (M-SPE) covered with glucose oxidase (M-GOX-SPE) or tyrosinase (M-Tyr-SPE).The M-GOX-SPE and M-Tyr-SPE sensors produced a variety of responses due to the different behavior of the electron mediators of the six screen-printed materials used for the electro-catalysis of the glucose and phenols by means of glucose oxidase and tyrosinase.This variety of responses, together with the capability of the sensors to detect glucose or phenols, allowed the bioelectronic tongue developed here to discriminate between the juices obtained from different varieties of grape.Partial least-squares (PLS-1) multivariate calibration of electrochemical data has been successfully applied to the simultaneous determination of glucose and polyphenols in musts.The discrimination capability shown by this array of cheap and single-use sensors was similar to that found in other complex bioelectronic tongues. The lower price, ease of use and portability of the modified screen-printed electrode system makes the bioelectronic tongue developed here an alternative tool that can be used in situ in the vineyard block.

Recent achievements in electronic tongue and bioelectronic tongue as taste sensors

This review presents recent achievements concerning work with electronic tongue (ET) and bioelectronic tongue (BioET) for taste assessment. These two emerging analytical technologies can be designed as taste sensors, which simulate the taste detection modality of human tongue by means of electrochemical sensors or biosensors array. For electronic tongue, the potentiometric and voltammetric types are mainly discussed together with applications in food and pharmaceutical analyses. Enzymatic and gustatory receptor-based biosensors towards bioelectronic tongues are presented.

Electronic and bioelectronic tongues, two promising analytical tools for the quality evaluation of non alcoholic beer

Authentication of the flavor of non alcoholic beer and control of its quality according to the present standards is an actual challenge in brewery. Electronic and bioelectronic tongues, which could be known as the taste sensors, are the advanced and emerging analytical technologies simulating the taste detection modality of the human tongue by means of electrochemical sensors or biosensors array. Although, application of electronic tongue has been reported for alcoholic beers but no work on the flavor sensory evaluation of non alcoholic beer by use of bioelectronic tongue has been published. Employment of electronic and bioelectronic tongues can reduce some problems in quality control of non alcoholic beers. Recently published works show a promising perspective for the fulfillment of this goal. This paper discusses and concludes that these analytical tools have a high potential application in brewery to monitor the flavor of non alcoholic beer in the immediate future.

State of the Art in the Field of Electronic and Bioelectronic Tongues – Towards the Analysis of Wines

AbstractThis review compares various types of (bio)electronic tongues. The design and principles of potentiometric and voltammetric electronic tongues are discussed together with applications in food and environmental analysis. Different approaches towards bioelectronic tongue are presented. Several methods for evaluation and interpretation of the measured data are described. Finally, the potential of such devices for analysis of wine is discussed.