Current State of Sensors and Sensing Systems Utilized in Beer Analysis

Beer is one of the most consumed beverages in the world. Advances in instrumental techniques have allowed the analysis and characterization of a large number of beers. However, review studies that outline the methodologies used in beer characterization are scarce. Herein, a systematic review investigating the molecular targets and sensometric techniques in beer characterization was performed following the PRISMA protocol. The study reviewed 270 articles related to beer analysis in order to provide a comprehensive summary of the recent advances in beer analysis, including methods using sensors and sensing systems. The results revealed the use of various techniques that include several technologies, such as nanotechnology and electronics, often combined with scientific data analysis tools. To our knowledge, this study is the first of its kind and provides the reader with a faithful overview of what has been done in the sensor field regarding beer characterization.

Phenothiazine and semi-cyanine based colorimetric and fluorescent probes for detection of sulfites in solutions and in living cells

Four hemicyanine probes for selectively detecting sulfites (HSO₃⁻/SO₃²⁻) have been constructed by the condensation reaction of 7-substituted (CN, Br, H and OH) phenothiazine aldehyde with 1-ethyl-2,3,3-trimethylindolium iodide. All four probes show a fast and sensitive response to HSO₃⁻/SO₃²⁻via a Michael addition, with a detection limit lower than 40 nM based on monitoring their UV/vis absorption changes. Although all four probes display an increase in fluorescence when responding to HSO₃⁻/SO₃²⁻, the increment is larger for the probe with an electron-withdrawing group than the probe with an electron-donating group, except for Br. Thus, among four probes the 7-cyano probe (PI-CN) possesses the largest fluorescent response to HSO₃⁻/SO₃²⁻, and the lowest detection limit (7.5 nM). More expediently and easily, a film and a test paper with PI-CN have been prepared to detect HSO₃⁻/SO₃²⁻ in a sample aqueous solution selectively. Finally, the detection of HSO₃⁻/SO₃²⁻ by PI-CN in biological environments has been demonstrated by cell imaging.

Four 7-substituted phenothiazine hemicyanines display a substituent effect on the fluorescence response toward sulfites. The CN-substituted probe exhibits the best sensing behavior.

AIEgens: An emerging fluorescent sensing tool to aid food safety and quality control

As a global public health problem, food safety has attracted increasing concern. To minimize the risk exposure of food to harmful ingredients, food quality and safety inspection that covers the whole process of "from farm to fork" is much desired. Fluorescent sensing is a promising and powerful screening tool for sensing hazardous substances in food and thus plays a crucial role in promoting food safety assurance. However, traditional fluorphores generally suffer the problem of aggregation-caused quenching (ACQ) effect, which limit their application in food quality and safety inspection. In this regard, luminogens with aggregation-induced emission property (AIEgens) showed large potential in food analysis since AIEgens effectively surmount the ACQ effect with much better detection sensitivity, accuracy, and robustness. In this contribution, we review the latest developments of food safety monitoring by AIEgens, which will focus on the molecular design of AIEgens and their sensing principles. Several examples of AIE-based sensing applications for screening food contaminations are highlighted, and future perspectives and challenges in this emerging field are tentatively elaborated. We hope this review can motivate new research ideas and interest to aid food safety and quality control, and facilitate more collaborative endeavors to advance the state-of-the-art sensing developments and reduce actual translational gap between laboratory research and industrial production.

Supramolecular Hyaluronic Assembly with Aggregation-Induced Emission Mediated in Two Stages for Targeting Cell Imaging

Supramolecular aggregation-induced emission (AIE) has become a research hotspot in cell imaging. Herein, supramolecular assembly with AIE effect was constructed in two stages, where adamantane modified tetraphenylethene self-assembly emitted weak fluorescence, and then after adding β-cyclodextrin modified hyaluronic acid, the formed nanoparticles enhanced AIE fluorescence for targeted cancer cell imaging.

A new ratiometric fluorescence assay based on resonance energy transfer between biomass quantum dots and organic dye for the detection of sulfur dioxide derivatives

Sulfur dioxide (SO₂) is considered as the fourth gas signal molecule after nitric oxide (NO), carbon monoxide (CO) and hydrogen sulfide (H₂S). It plays important roles in several physiological processes. Therefore, the design and synthesis of nanoprobes for the detection of SO₂ derivatives in cells is of great significance. Herein, we report a new ratiometric fluorescence nanoprobe based on resonance energy transfer (RET) between biomass quantum dots (BQDs) and organic dye (DMI) for the detection of SO₂ derivatives. The proposed ratiometric fluorescence assay allows the determination of HSO₃⁻ in the range of 1.0 to 225 μM with a detection limit of 0.5 μM. Importantly, the proposed ratiometric fluorescence nanoprobe exhibits a high photostability and good selectivity for HSO₃⁻ over other chemical species including H₂S and biological mercaptans. Quantitation of HSO₃⁻ in cell lysates by using the nanoprobe is demonstrated.

A new ratiometric fluorescence assay has been developed for the detection of sulfur dioxide derivatives with repeatability and selectivity. The assay was applied to quantitate HSO₃⁻ in cell lysates with accurate results.

Design of mitochondria-targeted colorimetric and ratiometric fluorescent probes for rapid detection of SO2 derivatives in living cells

Two mitochondria-targeted colorimetric and ratiometric fluorescent probes for SO₂ derivatives were constructed based on the SO₂ derivatives-triggered Michael addition reaction. The probes exhibit high specificity toward HSO₃^-/SO₃^2- by interrupting their conjugation system resulting in a large ratiometric blue shift of 46-121nm in their emission spectrum. The two well-resolved emission bands can ensure accurate detection of HSO₃^-. The detection limits were calculated to be 1.09 and 1.35μM. Importantly, probe 1 and probe 2 were successfully used to fluorescence ratiometric imaging of endogenous HSO₃^- in BT-474 cells.

Fluorescence of ZnO/carbon mixture and application in acid rain detection

ZnO and carbon mixture as dual-emission ratiometric fluorescent sensor of acid rain have been demonstrated.

Cell-penetrating poly(disulfide)-based star polymers for simultaneous intracellular delivery of miRNAs and small molecule drugs

A cell-penetrating poly(disulfide)-based star-like system with high transfection efficacy for synergistic delivery of miRNAs and chemotherapeutic drugs has been reported.

A dual functional probe: sensitive fluorescence response to H2S and colorimetric detection for SO32−

In this study, we developed a new dual functional probe,NIR-DNP, for discriminative detection of H₂S and SO₃²⁻.

Fabrication of amphiphilic fluorescent nanoparticles with an AIE feature via a one-pot clickable mercaptoacetic acid locking imine reaction: synthesis, self-assembly and bioimaging

Water dispersible and non-toxic AIE active fluorescent organic nanoparticles were fabricatedviaa one-pot clickable mercaptoacetic acid locking imine reaction.

Chemical probes for molecular imaging and detection of hydrogen sulfide and reactive sulfur species in biological systems

Hydrogen sulfide (H2S), a gaseous species produced by both bacteria and higher eukaryotic organisms, including mammalian vertebrates, has attracted attention in recent years for its contributions to human health and disease. H2S has been proposed as a cytoprotectant and gasotransmitter in many tissue types, including mediating vascular tone in blood vessels as well as neuromodulation in the brain. The molecular mechanisms dictating how H2S affects cellular signaling and other physiological events remain insufficiently understood. Furthermore, the involvement of H2S in metal-binding interactions and formation of related RSS such as sulfane sulfur may contribute to other distinct signaling pathways. Owing to its widespread biological roles and unique chemical properties, H2S is an appealing target for chemical biology approaches to elucidate its production, trafficking, and downstream function. In this context, reaction-based fluorescent probes offer a versatile set of screening tools to visualize H2S pools in living systems. Three main strategies used in molecular probe development for H2S detection include azide and nitro group reduction, nucleophilic attack, and CuS precipitation. Each of these approaches exploits the strong nucleophilicity and reducing potency of H2S to achieve selectivity over other biothiols. In addition, a variety of methods have been developed for the detection of other reactive sulfur species (RSS), including sulfite and bisulfite, as well as sulfane sulfur species and related modifications such as S-nitrosothiols. Access to this growing chemical toolbox of new molecular probes for H2S and related RSS sets the stage for applying these developing technologies to probe reactive sulfur biology in living systems.

A simple levulinate-based ratiometric fluorescent probe for sulfite with a large emission shift

A simple 4-hydroxynaphthalimide-derived colorimetric and ratiometric fluorescent probe (1) containing a receptor of levulinate moiety was designed and synthesized to monitor sulfite. Probe 1 could quantificationally detect sulfite by a ratiometric fluorescence spectroscopy method with high selectivity and sensitivity. Specially, probe 1 exhibited a 100 nm red-shifted absorption spectrum along with the color changes from colorless to yellow, and 103 nm red-shifted emission spectra upon the addition of sulfite. Thus, 1 can serve as a "naked-eye" probe for sulfite. Further, the recognition mechanism of probe 1 for sulfite was confirmed using nuclear magnetic resonance and electrospray ionization mass spectrometry. Also, the preliminary practical application demonstrated that our proposed probe provided a promising method for the determination of sulfite.

A new diketopyrrolopyrrole-based probe for sensitive and selective detection of sulfite in aqueous solution

A new probe was synthesized by incorporating an α,β-unsaturated ketone to a diketopyrrolopyrrole fluorophore. The probe had exhibited a selective and sensitive response to the sulfite against other thirteen anions and biothiols (Cys, Hcy and GSH), through the nucleophilic addition of sulfite to the alkene of probe with the detection limit of 0.1 μM in HEPES (10 mM, pH 7.4) THF/H2O (1:1, v/v). Meanwhile, it could be easily observed that the probe for sulfite changed from pink to colorless by the naked eye, and from pink to blue under UV lamp after the sulfite was added for 20 min. The NMR and Mass spectral analysis demonstrated the expected addition of sulfite to the C=C bonds.

A ratiometric fluorescent probe for rapid, sensitive and selective detection of sulfur dioxide with large Stokes shifts by single wavelength excitation

A ratiometric fluorescent probe was developed for rapid, sensitive and selective detection of SO₃²⁻ with large Stokes shifts. Imaging intracellular SO₃²⁻ was successfully demonstrated in living HNE-2 cells.

Enzymatic ‘charging’ of synthetic polymers

Enzymatic action is shown to transform a chemically neutral polymer chain into a chemically charged cationic structure.

A real-time colorimetric and ratiometric fluorescent probe for rapid detection of SO2 derivatives in living cells based on a near-infrared benzopyrylium dye

Near-infrared benzopyrylium dye was employed as a fast-responding ratiometric fluorescent probe for sensitive and selective detection of SO₂ derivatives in 100% aqueous solution as well as in living cells.

Selective, highly sensitive fluorescent probe for the detection of sulfur dioxide derivatives in aqueous and biological environments

On the basis of a unique nucleophilic addition reaction, a novel water-soluble broadly emitting (500-700 nm) fluorescent Probe 1 was developed for the rapid detection of SO2 derivatives in aqueous media. The positively-charged benzopyrylium moiety in Probe 1 provides both excellent water solubility, making this probe applicable in 100% aqueous environments, and the ability to function as a fluorescence quencher of the coumarin moiety. Probe 1 generates a nearly instantaneous strong fluorescence signal in response to SO2 derivatives having an 8.3 nM detection limit for bisufite. The resulting Probe 1-sulfite adduct emits in the green/red spectral region (λ(max) = 585 nm) with a large Stokes shift (139 nm). The probe exhibits excellent selectivity toward SO2 derivatives over other potential interfering agents including reactive sulfur-containing species. Importantly, we demonstrate that Probe 1 can be used for the real-time sensing and bioimaging of SO2 derivatives in living cells.

Determination of gaseous sulfur dioxide and its derivatives via fluorescence enhancement based on cyanine dye functionalized carbon nanodots

The development of convenient methods for sulfur dioxide and its derivatives analysis is critically important because SO2 causes worldwide serious environmental problems and human diseases. In this work, we show an unprecedented example of an energy-transfer-based fluorescence nanoprobe for selective and quantitative detection of SO2, through molecular engineering of the fluorescent carbon nanodots by a cyanine dye which have a unique reactivity to bisulfite, achieving a detection limit of 1.8 μM with a linear relationship (R(2) = 0.9987). The specific detection was not interfered with other potential coexisted species. In addition, the probe is demonstrated for the determination of SO2 gas in aqueous solution as well as for visually monitoring of SO2 gas in air. This nanomaterial based probe is easily prepared, fast responding, and thus potentially attractive for extensive application for the determination of SO2 and other similar air pollutants.

Selective and sensitive chromofluorogenic detection of the sulfite anion in water using hydrophobic hybrid organic-inorganic silica nanoparticles

In water and wine: Chromofluorogenic detection of the sulfite anion in pure water was accomplished by using a new hybrid organic-inorganic material that contained a probe entrapped in hydrophobic biomimetic cavities. This material was used for the detection of sulfite in red wine.