Sweet and bitter tastants specific detection by the taste cell-based sensor

One of the major challenges of masking the bitter taste in medications: an overview of quantitative methods for bitterness

Objective

The aim of the present study was to carry out a systematic research on bitterness quantification to provide a reference for scholars and pharmaceutical developers to carry out drug taste masking research. Significance: The bitterness of medications poses a significant concern for clinicians and patients. Scientifically measuring the intensity of drug bitterness is pivotal for enhancing drug palatability and broadening their clinical utility.

Methods

The current study was carried out by conducting a systematic literature review that identified relevant papers from indexed databases. Numerous studies and research are cited and quoted in this article to summarize the features, strengths, and applicability of quantitative bitterness assessment methods.

Results

In our research, we systematically outlined the classification and key advancements in quantitative research methods for assessing drug bitterness, including in vivo quantification techniques such as traditional human taste panel methods, as well as in vitro quantification methods such as electronic tongue analysis. It focused on the quantitative methods and difficulties of bitterness of natural drugs with complex system characteristics and their difficulties in quantification, and proposes possible future research directions.

Conclusion

The quantitative methods of bitterness were summarized, which laid an important foundation for the construction of a comprehensive bitterness quantification standard system and the formulation of accurate, efficient and rich taste masking strategies.

Recent advancements in the taste transduction mechanism, identification, and characterization of taste components

In the realm of human nutrition, the phenomenon known as taste refers to a distinctive sensation elicited by the consumption of food and various compounds within the oral cavity and on the tongue. Moreover, taste affects the overall comfort in the oral cavity, and is a fundamental attribute for the assessment of food items. Accordingly, clarifying the material basis of taste would be conducive to deepening the cognition of taste, investigating the mechanism of taste presentation, and accurately covering up unpleasant taste. In this paper, the basic biology and physiology of transduction of bitter, umami, sweet, sour, salty, astringent, as well as spicy tastes are reviewed. Furthermore, the detection process of taste components is summarized. Particularly, the applications, advantages, and distinctions of various isolation, identification, and evaluation methods are discussed in depth. In conclusion, the future of taste component detection is discussed.

Recent Advances in Bitterness-Sensing Systems

Bitterness is one of the basic tastes, and sensing bitterness plays a significant role in mammals recognizing toxic substances. The bitter taste of food and oral medicines may decrease consumer compliance. As a result, many efforts have been made to mask or decrease the bitterness in food and oral pharmaceutical products. The detection of bitterness is critical to evaluate how successful the taste-masking technology is, and many novel taste-sensing systems have been developed on the basis of various interaction mechanisms. In this review, we summarize the progress of bitterness response mechanisms and the development of novel sensors in detecting bitterness ranging from commercial electronic devices based on modified electrodes to micro-type sensors functionalized with taste cells, polymeric membranes, and other materials in the last two decades. The challenges and potential solutions to improve the taste sensor quality are also discussed.

Human-like performance umami electrochemical biosensor by utilizing co-electrodeposition of ligand binding domain T1R1-VFT and Prussian blue

Over the past decades, due to the desire for artificial umami flavors, apparatuses for detecting the umami taste have constantly been developed. Nevertheless, most information on umami is still acquired through human sensory assessment, which makes it difficult to establish an umami standard or quantify the umami flavor. In this study, the ligand binding domain called venus flytrap (VFT) domain of the umami taste receptor protein T1R1 was used as a recognition element, and an electrochemical biosensor based on a double-signal amplification strategy was constructed using single-walled carbon nanotubes (SWCNTs) and Prussian blue (PB). Moreover, the umami taste of four representative umami substances, inosine-5'-monophosphate (IMP), monosodium L-glutamate (MSG), beefy meaty peptide (BMP), and sodium succinate (WSA), were successfully quantitatively measured using differential pulse voltammetry (DPV) at an electrochemical workstation. Based on an equation (S/N = 3), the low detection limits (LODs) of IMP, MSG, BMP, and WSA were 0.1, 0.1, 0.1, and 0.01 pM, respectively. Meanwhile, a normalized signal intensity of more than 90% was kept for 4 days. The results showed that the biosensor could be used to detect umami substances with high sensitivity and selectivity, and was shown to have human-like performance. To develop the T1R1-VFT biosensor using the above-mentioned method, we utilized the ligand binding domain of the human umami receptor, rather than the entire umami receptor protein, which had a complex structure, having the following advantages: volume reduction, simplicity, and stability. This method has great potential for the detection of umami tastes, instead of using sensory evaluation, and for the development of new artificial flavorings.

Bitter taste in silico: A review on virtual ligand screening and characterization methods for TAS2R-bitterant interactions

The growing pharmaceutical interest in the human bitter taste receptors (hTAS2Rs) has two dimensions; i) evaluation of the bitterness of active pharmaceutical compounds, in order to develop strategies for improving patients' adherence to medication, and ii) application of ligands for extra-cellular hTAS2Rs for potential preventive therapeutic achievements. The result is an increasing demand on robust tools for bitterness assessment and screening the receptor-ligand affinity. In silico tools are useful for aiding experimental-screening, as well as to elucide ligand-receptor interactions. In this review, the ligand-based and structure-based approaches are described as the two main in silico tools for bitter taste analysis. The strengths and weaknesses of each approach are discussed. Both approaches provide key tools for understanding and exploiting bitter taste for human health applications.

Redox phospholipidomics of enzymatically generated oxygenated phospholipids as specific signals of programmed cell death

High fidelity and effective adaptive changes of the cell and tissue metabolism to changing environments require strict coordination of numerous biological processes. Multicellular organisms developed sophisticated signaling systems of monitoring and responding to these different contexts. Among these systems, oxygenated lipids play a significant role realized via a variety of re-programming mechanisms. Some of them are enacted as a part of pro-survival pathways that eliminate harmful or unnecessary molecules or organelles by a variety of degradation/hydrolytic reactions or specialized autophageal processes. When these "partial" intracellular measures are insufficient, the programs of cells death are triggered with the aim to remove irreparably damaged members of the multicellular community. These regulated cell death mechanisms are believed to heavily rely on signaling by a highly diversified group of molecules, oxygenated phospholipids (PLox). Out of thousands of detectable individual PLox species, redox phospholipidomics deciphered several specific molecules that seem to be diagnostic of specialized death programs. Oxygenated cardiolipins (CLs) and phosphatidylethanolamines (PEs) have been identified as predictive biomarkers of apoptosis and ferroptosis, respectively. This has led to decoding of the enzymatic mechanisms of their formation involving mitochondrial oxidation of CLs by cytochrome c and endoplasmic reticulum-associated oxidation of PE by lipoxygenases. Understanding of the specific biochemical radical-mediated mechanisms of these oxidative reactions opens new avenues for the design and search of highly specific regulators of cell death programs. This review emphasizes the usefulness of such selective lipid peroxidation mechanisms in contrast to the concept of random poorly controlled free radical reactions as instruments of non-specific damage of cells and their membranes. Detailed analysis of two specific examples of phospholipid oxidative signaling in apoptosis and ferroptosis along with their molecular mechanisms and roles in reprogramming has been presented.

Bioelectronic tongue: Current status and perspectives

In the course of evolution, nature has endowed humans with systems for the recognition of a wide range of tastes with a sensitivity and selectivity which are indispensable for the evaluation of edibility and flavour attributes. Inspiration by a biological sense of taste has become a basis for the design of instruments, operation principles and parameters enabling to mimic the unique properties of their biological precursors. In response to the demand for fast, sensitive and selective techniques of flavouring analysis, devices belonging to the group of bioelectronic tongues (B-ETs) have been designed. They combine achievements of chemometric analysis employed for many years in electronic tongues (ETs), with unique properties of bio-inspired materials, such as natural taste receptors (TRs) regarding receptor/ligand affinity. Investigations of the efficiency of the prototype devices create new application possibilities and suggest successful implementation in real applications. With advances in the field of biotechnology, microfluidics and nanotechnologies, many exciting developments have been made in the design of B-ETs in the last five years or so. The presented characteristics of the recent design solutions, application possibilities, critical evaluation of potentialities and limitations as well as the outline of further development prospects related to B-ETs should contribute to the systematisation and expansion of our knowledge.

Ion Chromatographic Fingerprinting of STC-1 Cellular Response for Taste Sensing

Taste sensing is of great importance in both the pharmaceutical and foodstuff industries, and is currently mainly based on human sensory evaluation. Many approaches based on chemical sensors have been proposed, leading to the development of various electronic tongue systems. However, this approach is limited by the applied recognition methods, which do not consider natural receptors. Biorecognition elements such as taste receptor proteins or whole cells can be involved in the development of taste sensing biosensors usually equipped with various electrochemical transducers. Here, we propose a new approach: intestinal secretin tumor cell line (STC-1) chemosensory cells were applied for taste recognition, and their taste-specific cellular response was decoded from ion chromatographic fingerprints with the use of multivariate data processing by partial least squares discriminant analysis (PLS-DA). This approach could be useful for the development of various non-invasive taste sensing assays, as well as for studying taste transduction mechanisms in vitro.

DNA-mediated self-assembly of taste cells and neurons for taste signal transmission

Cells can communicate with one another through physical connections and chemical signaling, activating various signaling pathways that can affect cellular functions and behaviors. In taste buds, taste cells transmit taste information to neurons via paracrine signaling. However, no previous studies have reported the in vitro co-culture of taste and neuronal cells, which allows us to monitor intercellular communications and better understand the mechanism of taste perception. Here, we introduce the first investigation on the proximate assembly and co-culture of taste cells and neurons to monitor the intercellular transmission of taste signals. Taste cells and neurons are placed closely using a pair of single-stranded oligonucleotides conjugated with polyethylene glycol and a phospholipid. Complementary oligonucleotide conjugates are anchored into the cellular membrane of neonatal taste cells and embryonic hippocampal neuronal cells, respectively, and then the cells are self-assembled into a functional multicellular unit for taste perception. Treatment of the assembled cells with a bitter tastant generates the sequential influx of calcium ions into the cytoplasm in taste cells and then in neuronal cells. Our work demonstrates that the cellular self-assembly is critical for efficient taste signal transduction, which can be used as a promising platform to construct cell-based biosensors for taste sensing.

Recent progress on cell-based biosensors for analysis of food safety and quality control

Food quality and safety has become a subject of major concern for authorities and professionals in the food supply chain. Rapid methods, particularly biosensors, have exceptional specificity and sensitivity, rapid response times, low cost, relatively compact size, and are user friendly to operate. Cell-based biosensors are portable, and provide the biological activity of the analyte suitable for an initial screening of food. In this overview, the utilization of cell-based biosensors for food safety and quality analyses, such as detecting toxins, foodborne pathogens, allergens, and evaluating toxicity and function are summarized. Our results will promote the future development of cell-based biosensors in the food field.

Biomimetic Sensors for the Senses: Towards Better Understanding of Taste and Odor Sensation

Taste and smell are very important chemical senses that provide indispensable information on food quality, potential mates and potential danger. In recent decades, much progress has been achieved regarding the underlying molecular and cellular mechanisms of taste and odor senses. Recently, biosensors have been developed for detecting odorants and tastants as well as for studying ligand-receptor interactions. This review summarizes the currently available biosensing approaches, which can be classified into two main categories: in vitro and in vivo approaches. The former is based on utilizing biological components such as taste and olfactory tissues, cells and receptors, as sensitive elements. The latter is dependent on signals recorded from animals' signaling pathways using implanted microelectrodes into living animals. Advantages and disadvantages of these two approaches, as well as differences in terms of sensing principles and applications are highlighted. The main current challenges, future trends and prospects of research in biomimetic taste and odor sensors are discussed.

Duplex Bioelectronic Tongue for Sensing Umami and Sweet Tastes Based on Human Taste Receptor Nanovesicles

For several decades, significant efforts have been made in developing artificial taste sensors to recognize the five basic tastes. So far, the well-established taste sensor is an E-tongue, which is constructed with polymer and lipid membranes. However, the previous artificial taste sensors have limitations in various food, beverage, and cosmetic industries because of their failure to mimic human taste reception. There are many interactions between tastants. Therefore, detecting the interactions in a multiplexing system is required. Herein, we developed a duplex bioelectronic tongue (DBT) based on graphene field-effect transistors that were functionalized with heterodimeric human umami taste and sweet taste receptor nanovesicles. Two types of nanovesicles, which have human T1R1/T1R3 for the umami taste and human T1R2/T1R3 for the sweet taste on their membranes, immobilized on micropatterned graphene surfaces were used for the simultaneous detection of the umami and sweet tastants. The DBT platform led to highly sensitive and selective recognition of target tastants at low concentrations (ca. 100 nM). Moreover, our DBT was able to detect the enhancing effect of taste enhancers as in a human taste sensory system. This technique can be a useful tool for the detection of tastes instead of sensory evaluation and development of new artificial tastants in the food and beverage industry.

Bioanalytical and chemical sensors using living taste, olfactory, and neural cells and tissues: a short review

Biosensors utilizing living tissues and cells have recently gained significant attention as functional devices for chemical sensing and biochemical analysis. These devices integrate biological components (i.e. single cells, cell networks, tissues) with micro-electro-mechanical systems (MEMS)-based sensors and transducers. Various types of cells and tissues derived from natural and bioengineered sources have been used as recognition and sensing elements, which are generally characterized by high sensitivity and specificity. This review summarizes the state of the art in tissue- and cell-based biosensing platforms with an emphasis on those using taste, olfactory, and neural cells and tissues. Many of these devices employ unique integration strategies and sensing schemes based on sensitive transducers including microelectrode arrays (MEAs), field effect transistors (FETs), and light-addressable potentiometric sensors (LAPSs). Several groups have coupled these hybrid biosensors with microfluidics which offers added benefits of small sample volumes and enhanced automation. While this technology is currently limited to lab settings due to the limited stability of living biological components, further research to enhance their robustness will enable these devices to be employed in field and clinical settings.

Penaeus orientolis prawn freshness rapid determination method based on electronic nose and non-linear stochastic resonance technique

In this paper, Penaeus orientolis prawn freshness rapid determination method using electronic nose (e-nose) and non-linear data processing technique is studied. E-nose responses to prawns stored at 4 °C are measured. Meanwhile, physical/chemical indexes (firmness, pH, total volatile basic nitrogen (TVB-N), total viable count (TVC), and human sensory evaluation) are examined to provide freshness references for e-nose analysis. E-nose measurement data is analyzed by principal component analysis (PCA), stochastic resonance (SR), and double-layered cascaded serial stochastic resonance (DCSSR). PCA partially discriminates prawns under different storage time. SR and DCSSR signal-to-noise ratio (SNR) spectrum eigen values discriminate prawns successfully. Multi-variables regressions (MVR) are conducted between physical/chemical indexes and SR/DCSSR output SNR minimal (SNR-Min) values. Results indicate that SNR-Min values present more significant linearity relation with physical/chemical indexes. Prawn freshness forecasting model is developed via Harris fitting regression on DCSSR SNR-Min values. Validating experiments demonstrate that forecasting accuracy of this model is 94.29%.

Biomimetic chemical sensors using bioengineered olfactory and taste cells

Biological olfactory and taste systems are natural chemical sensing systems with unique performances for the detection of environmental chemical signals. With the advances in olfactory and taste transduction mechanisms, biomimetic chemical sensors have achieved significant progress due to their promising prospects and potential applications. Biomimetic chemical sensors exploit the unique capability of biological functional components for chemical sensing, which are often sourced from sensing units of biological olfactory or taste systems at the tissue level, cellular level, or molecular level. Specifically, at the cellular level, there are mainly two categories of cells have been employed for the development of biomimetic chemical sensors, which are natural cells and bioengineered cells, respectively. Natural cells are directly isolated from biological olfactory and taste systems, which are convenient to achieve. However, natural cells often suffer from the undefined sensing properties and limited amount of identical cells. On the other hand, bioengineered cells have shown decisive advantages to be applied in the development of biomimetic chemical sensors due to the powerful biotechnology for the reconstruction of the cell sensing properties. Here, we briefly summarized the most recent advances of biomimetic chemical sensors using bioengineered olfactory and taste cells. The development challenges and future trends are discussed as well.

Winter jujube (Zizyphus jujuba Mill.) quality forecasting method based on electronic nose

Winter jujube (Zizyphus jujuba Mill.) quality forecasting method utilising electronic nose (EN) and double-layered cascaded series stochastic resonance (DCSSR) was investigated. EN responses to jujubes stored at room temperature were continuously measured for 8 days. Jujubes' physical/chemical indexes, such as firmness, colour, total soluble solids (TSS), and ascorbic acid (AA), were synchronously examined. Examination results indicated that jujubes were getting ripe during storage. EN measurement data was processed by stochastic resonance (SR) and DCSSR. SR and DCSSR output signal-to-noise ratio (SNR) maximums (SNR-MAX) discriminated jujubes under different storage time successfully. Multiple variable regression (MVR) results between physical/chemical indexes and SR/DCSSR eigen values demonstrated that DCSSR eigen values were more suitable for jujube quality determination. Quality forecasting model was developed using non-linear fitting regression of DCSSR eigen values. Validating experiments demonstrated that forecasting accuracy of this model is 97.35%. This method also presented other advantages including fast response, non-destructive, etc.