A highly sensitive ratiometric fluorescence probe for sensing and imaging sulfite in food samples and living cells

In this work, a ratiometric and chromogenic fluorescent probe 1 was synthesized for the detection of SO32-. The probe 1 at PBS (10 mM, pH = 7.4) presented a marked emission band at 661 nm. Upon addition of SO32- ions, a highly emissive adduct with a marked fluorescence at 471 nm were obtained through a Michael addition. The probe 1 displayed a noticeable fluorescence ratiometric response with a large shift (190 nm) in emission wavelength. The probe can quantitatively detect SO32- with high specificity, fast response (within 130 s) as well as low detection limit (13 nM), and a large Stokes shift (139 nm). Fluorescence imaging of HeLa cells indicated that 1 could be used for monitoring the intrinsically generated intracellular SO32- in living cells by ratiometric fluorescence imaging. Furthermore, 1 could be application in real water and sugar samples with high sensitivity and good recoveries.

A highly sensitive ratiometric fluorescent probe for detecting HSO3-/SO32- and viscosity change based on FRET/TICT mechanism

BACKGROUND

Sulfur dioxide (SO2) is a significant gas signaling molecule in organisms, and viscosity is a crucial parameter of the cellular microenvironment. They are both involved in regulating many physiological processes in the human body. However, abnormalities in SO2 and viscosity levels are associated with various diseases, such as cardiovascular disease, lung cancer, respiratory diseases, neurological disorders, diabetes and Alzheimer's disease. Hence, it is essential to explore novel and efficient fluorescent probes for simultaneously monitoring SO2 and viscosity in organisms.

RESULTS

We selected quinolinium salt with good stability, high fluorescence intensity, good solubility and low cytotoxicity as the fluorophore and developed a highly sensitive ratiometric probe QQD to identify SO2 and viscosity changes based on Förster resonance energy transfer/twisted intramolecular charge transfer (FRET/TICT) mechanism. Excitingly, compared with other probes for SO2 detection, QQD not only identified HSO3-/SO32- with a large Stokes shift (218 nm), low detection limit (1.87 μM), good selectivity, high energy transfer efficiency (92 %) and wide recognition range (1.87-200 μM), but also identified viscosity with a 26-fold fluorescence enhancement and good linearity. Crucially, QQD was applied to detect HSO3-/SO32- and viscosity in actual water and food samples. In addition, QQD had low toxicity and good photostability for imaging HSO3-/SO32- and viscosity in cells. These results confirmed the feasibility and reliability of QQD for HSO3-/SO32- and viscosity imaging and environmental detection.

SIGNIFICANCE

We reported a unique ratiometric probe QQD for detecting HSO3-/SO32- and viscosity based on the quinolinium skeleton. In addition to detecting HSO3-/SO32- and viscosity change in actual water and food samples, QQD could also monitor the variations of HSO3-/SO32- and viscosity in cells, which provided an experimental basis for further exploration of the role of SO2 derivatives and viscosity in biological systems.

A ratiometric fluorescent probe based on the FRET platform for the detection of sulfur dioxide derivatives and viscosity

BACKGROUND

Sulfur dioxide (SO2) is a common gaseous pollutant that significantly threatens environmental pollution and human health. Meanwhile, viscosity is an essential parameter of the intracellular microenvironment, manipulating many physiological roles such as nutrient transport, metabolism, signaling regulation and apoptosis. Currently, most of the fluorescent probes used for detecting SO2 derivatives and viscosity are single-emission probes or probes based on the ICT mechanism, which suffer from short emission wavelengths, small Stokes shifts or susceptibility to environmental background. Therefore, the development of powerful high-performance probes for real-time monitoring of sulfur dioxide derivatives and viscosity is of great significance for human health.

RESULTS

In this research, we designed the fluorescent probe QQC to detect SO2 derivatives and viscosity based on FRET platform with quinolinium salt as donor and quinolinium-carbazole as acceptor. QQC exhibited a ratiometric fluorescence response to SO2 with a low detection limit (0.09 μM), large Stokes shift (186 nm) and high energy transfer efficiency (95 %), indicating that probe QQC had good sensitivity and specificity. In addition, QQC was sensitive to viscosity, with an 9.10-folds enhancement of orange fluorescence and an excellent linear relationship (R2 = 0.98) between the logarithm of fluorescence intensity at 592 nm and viscosity. Importantly, QQC could not only recognize SO2 derivatives in real water samples and food, but also detect viscosity changes caused by food thickeners and thereby had broad market application prospects.

SIGNIFICANCE

We have developed a ratiometric fluorescent probe based on the FRET platform for detecting sulfur dioxide derivatives and viscosity. QQC could not only successfully detect SO2 derivatives in food and water samples, but also be made into test strips for detecting HSO3-/SO32- solution. In addition, the probe was also used to detect viscosity changes caused by food thickeners. Therefore, this novel probe had significant value in food and environmental detection applications.

Development of a Ratiometric Fluorescent Probe with Zero Cross-Talk for the Detection of SO2 Derivatives in Foods and Live Cells

Sulfur dioxide (SO2) derivatives are extensively utilized as both a preservative for foods and an active gaseous signal molecule in various physiological and pathological processes, but their excessive intake would bring harmful effects on human health; so, the determination of SO2 derivatives is of great importance. Herein, we developed a ratiometric fluorescent probe named 2-(2'-hydroxyphenyl)benzothiazole-3-ethyl-1,1,2-trimethyl-1H-benzo[e]indolium (HBT-EMBI) by introducing a hemicyanine unit of EMBI to an HBT group for the detection of SO2 derivatives via an excited-state intramolecular proton transfer (ESIPT) and intramolecular charge transfer (ICT) effects. The probe displays some advantages, such as a colorimetric change from purple to colorless, a ratiometric fluorescence with zero cross-talk, and a remarkably large emission shift (Δλ = 164 nm) under a single-wavelength excitation. Accordingly, the probe HBT-EMBI has been successfully employed for the colorimetric and ratiometric determination of SO2 derivatives in real food samples and the quantitative visualization of SO2 derivative variations in HepG2 cells.

The association between intermediate-term sulfur dioxide exposure and outpatient visits for Parkinson's disease: a time-series study in southwestern China

Parkinson's disease (PD) is the second most common human neurodegenerative disorder, and the pathogenesis of it remains poorly understood. Limited studies have shown that both long- and short-term exposure to air pollutants may be associated with increased risk of PD while lacking evidence on the effects of intermediate-term exposure. In this study, over-dispersed Poisson generalized additive models (GAMs) were applied to explore the association between intermediate-term sulfur dioxide (SO2) exposure and outpatient visits for PD in Chongqing, China, and further stratified analyses were performed by age and gender. A total of 39,984 PD cases from January 1, 2014, to December 31, 2019 (2191 days) were included. The association of intermediate-term SO2 exposure with outpatient visits for PD was statistically significant: per 1 μg/m3 increase of SO2 corresponded to 2.34% (95% CI: 0.88%, 3.80%) elevation in monthly PD outpatient visits at lag 0 (the concurrent month). Stratified analyses showed that the associations between SO2 and PD outpatient visits were stronger in younger (≤ 60 years) and female patients. In conclusion, intermediate-term SO2 exposure can be associated with an increased risk of PD outpatient visits. Our results highlight the importance of recognizing the role of intermediate-term SO2 exposure in the development of PD. In addition to focusing on the effects of long-term or short-term air pollutants, it is necessary to pay more attention to the health effects of intermediate-term exposure time windows of air pollutants, which will facilitate policy formulation and public health interventions for health risks.

A FRET-based ratiometric fluorescent probe for SO32- detection in Chinese medicine and living cells

Chinese herbal medicine is receiving more and more attention at home and abroad as a traditional Chinese clinical medicine. To make herbal medicines can be preserved for a long time, they are usually fumigated with sulfur. However, after the medicinal materials have been fumigated with sulfur, SO₂ residues will remain, which, when exposed to water, will create sulfites and bisulfites. Excessive sulfites can cause a variety of severe ailments and diminish the quality and effectiveness of therapeutic plants. Therefore, developing an effective SO₃^2-/HSO₃^- detection method is important. This study chose coumarin derivatives as fluorescent acceptors and pyridinium acrylonitrile structures as fluorescent donors to create a ratiometric fluorescent probe CPA using the fluorescence resonance energy transfer (FRET) effect. The probe CPA exhibited a fluorescence transition from red to green under excitation at 405 nm with an interval of 149 nm, a reaction time of less than 1 min, a low detection limit of 86 nM, and the probe CPA has good specific recognition of SO₃^2- and is resistant to interference. In addition, CPA has low in vitro cytotoxicity and can successfully detect endogenous sulfites in living cells.

Prenatal PM2.5 exposure impairs spatial learning and memory in male mice offspring: from transcriptional regulation to neuronal morphogenesis

BACKGROUND

As one of the environmental risk factors for human health, atmospheric fine particulate matter (PM_2.5) contributes to cognitive deterioration in addition to respiratory and cardiovascular injuries. Recently, increasing evidence implicates that PM_2.5 inhalation can affect neurological functions in offspring, but the sex-specific outcomes and the underlying biological processes are largely unknown.

OBJECTIVES

To observe the influence of prenatal PM_2.5 exposure on cognitive performance in offspring, to elucidate the neuronal morphological alterations and possible transcriptional regulation based on mRNA-sequencing (mRNA-Seq) data after birth, and to determine the key components of PM_2.5 contributing to the adverse effects.

METHODS

Pregnant C57BL/6J mice were exposed to sterile saline or PM_2.5 suspension. Morris water maze test was used to assess the cognitive function in weanling offspring. Microscopic observation was applied to detect neuronal morphogenesis in vivo and in vitro. The cortex tissues from male offspring were collected on postnatal days (PNDs) 1, 7, and 21 for mRNA-Seq analysis. The organic and inorganic components of PM_2.5 were separated to assess their contributions using primary cultured neurons.

RESULTS

Prenatal PM_2.5 exposure impaired spatial learning and memory in weanling male mice, but not female mice. The sex-specific outcomes were associated with mRNA expression profiles of the cortex during postnatal critical windows, and the annotations in Gene Ontology (GO) of differentially expressed genes (DEGs) revealed that the exposure persistently disrupted the expression of genes involved in neuronal features in male offspring. Consistently, axonal growth impairment and dendritic complexity reduction were observed. Importantly, Homeobox A5 (Hoxa5), a critical transcription factor regulating all of the neuronal morphogenesis-associated hub genes on PNDs 1, 7, and 21, significantly decreased in the cortex of male offspring following PM_2.5 exposure. In addition, both inorganic and organic components were harmful to axonal and dendritic growth, with organic components exhibiting stronger inhibition than inorganic ones.

CONCLUSION

Prenatal PM_2.5 exposure affected spatial learning and memory in male mice by disrupting Hoxa5-mediated neuronal morphogenesis, and the organic components, including polycyclic aromatic hydrocarbons (PAHs), posed more adverse effects than the inorganic components.

Modifiable contributing factors to COVID-19: A comprehensive review

The devastating complications of coronavirus disease 2019 (COVID-19) result from an individual's dysfunctional immune response following the initial severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Multiple toxic stressors and behaviors contribute to underlying immune system dysfunction. SARS-CoV-2 exploits the dysfunctional immune system to trigger a chain of events ultimately leading to COVID-19. The current study identifies eighty immune system dysfunction-enabling toxic stressors and behaviors (hereafter called modifiable contributing factors (CFs)) that also link directly to COVID-19. Each CF is assigned to one of the five categories in the CF taxonomy shown in Section 3.3.: Lifestyle (e.g., diet, substance abuse); Iatrogenic (e.g., drugs, surgery); Biotoxins (e.g., micro-organisms, mycotoxins); Occupational/Environmental (e.g., heavy metals, pesticides); Psychosocial/Socioeconomic (e.g., chronic stress, lower education). The current study shows how each modifiable factor contributes to decreased immune system capability, increased inflammation and coagulation, and increased neural damage and neurodegeneration. It is unclear how real progress can be made in combatting COVID-19 and other similar diseases caused by viral variants without addressing and eliminating these modifiable CFs.

A near-infrared emitted fluorescence probe for the detection of biosulfite in live zebrafish, mouse and real food samples

Bisulfite (HSO₃^-) has been widely used as an important food additive in daily life. Furthermore, a normal amount of HSO₃^- plays a significant role in biological systems. However, excessive intake of HSO₃^- will lead to a variety of diseases. Therefore, it is of great significance to develop an efficient fluorescent probe that can be used for detection of HSO₃^- in biological systems and food samples. In this work, a near-infrared (NIR) emitted fluorescent probe (SZY) based on hemicyanine dye was successfully synthesized and applied to detect HSO₃^- in several food samples and live animals. The proposed nucleophilic addition sensing mechanism of SZY towards HSO₃^- has been confirmed by ¹H NMR titration, high resolution mass spectrometry (HR-MS) and density functional theory (DFT) theoretical computation. The HSO₃^--induced nucleophilic reaction with α,β-unsaturated C=C binding of SZY results in the dramatic decline of the UV-vis absorption and remarkable quenching of the fluorescence emission. SZY features the advantages of near infrared emission (centered at 720 nm), high water solubility (in 98% aqueous solution), fast response time (50 s), large Stokes shift (244 nm) and low cytotoxicity. The probe SZY was successfully applied to image of HSO₃^- in live nude mouse and adult zebrafish. Semi-quantitatively analyzing the HSO₃^- level by "naked eye" in several food samples including canned fruit, white wine, white sugar and jasmine tea drinks has been realized by the colorimetric method.

Kinetics, product distribution and atmospheric implications of the gas-phase oxidation of allyl sulfides by OH radicals

Relative rate coefficients of the OH radical -initiated oxidation of allyl methyl sulfide (AMS, H₂CCHCH₂SCH₃) and allyl ethyl sulfide (AES, H₂CCHCH₂SCH₂CH₃) have been measured at atmospheric pressure of synthetic air and 298 K: k_AMS= (4.98 ± 1.42) and k_AES= (6.88 ± 1.49) × 10^-11 cm³ molecule^-1 s^-1 by means of in situ FTIR spectroscopy. In addition, the molar yields of the main reaction products of AMS with OH radicals formed in the absence and presence of nitric oxides (NO_X) were determined to be the following: sulfur dioxide (95 ± 12) % and (51 ± 12) % for acrolein (50 ± 9) % and (41 ± 9) %. In the reaction of AES with OH radicals, the following molar yields were obtained: for sulfur dioxide (88 ± 13) % and (56 ± 12) % for acrolein (36 ± 9) % and (41 ± 9) %. The present results suggest that the abstraction at C3 plays an important role in the oxidation mechanism as the addition to the double bond. This work represents the first study of the OH radical interaction with AMS and AES carried out under atmospheric conditions. The atmospheric implications were discussed in terms of the atmospheric residence times of the sulfur-containing compounds studied and the products formed in the presence and absence of NOx. SO₂ formation seems to be the main fate of the gas-phase allyl sulfides oxidation with significant acidifying potentials and short-chain aldehydes production like formaldehyde and acetaldehyde.

A novel fluorescent probe for the detection of sulfur dioxide derivatives and its application in biological imaging

A new probe CA-SO2 to efficiently and specifically detect SO2 was designed. The probe showed a fast response time (<50 s), low detection limit (LOD = 75 nM), large Stokes shift (129 nm) and was applied to detect SO2 in living cells and zebrafish.

A highly sensitive chemosensor for rapid recognition of Cu2+ and HSO3- in 100% aqueous solution

Dual-responsive chemosensors have garnered much research interests owing to the ability of recognizing two analytes simultaneously. Herein, the chemosensor BPIS composed of hemicyanine and 2, 2'-dipyridylamine (DPA) was facilely synthesized for sensitive and expeditious recognition of Cu²⁺ and HSO₃^- in 100% aqueous solution. By adding Cu²⁺, BPIS showed substantial spectral changes accompanied by a noticeable color change from pink to yellow under daylight. The absorbance and fluorescence intensity were linearly correlated to the Cu²⁺ concentration, enabling the quantitative recognition of Cu²⁺. The limit of detection (LOD) for Cu²⁺ was down to 4.02 × 10^-9 M. The response time of BPIS towards Cu²⁺ was 10 s, imparting BPIS great potential in real-time detection of Cu²⁺. Meanwhile, BPIS manifested ratiometric fluorescence response by introducing HSO₃^- owing to the 1,4-addition between HSO₃^- and the unsaturated CC bond of BPIS. The color of the BPIS solution progressively faded from pink to colorless with increasing HSO₃^- concentration, and a LOD of 3.47 × 10^-9 M was obtained. In addition, BPIS-coated test paper was found to be an efficient tool for fast, sensitive, portable detection of Cu²⁺ and HSO₃^- by naked eyes. More importantly, the precise detection of Cu²⁺ and HSO₃^- in real water and sugars were realized, respectively, by capitalizing on BPIS as the signal tool.

Diketopyrrolopyrrole-based fluorescent probe for endogenous bisulfite detection and bisulfite triggered phototoxicity specific in liver cancer cells

As the main existing form of SO₂ derivatives, bisulfite showed closely relationship to many diseases. In this work, a new fluorescent probe (SDPP-DM) based on thienyl-substituted diketopyrrolopyrrole (SDPP) was designed and synthesized for the detection of endogenous bisulfite. The probe displayed obvious color changes from green to pink towards bisulfite due to the reduced conjugated length caused by the addition to the α,β-unsaturated double bond of its structure, and the change of the fluorescence intensity of SDPP-DM (I/I₀) was about 16 folds. In addition, SDPP-DM was prepared a test strip for bisulfite identified by naked eye through color and fluorescence changes. Besides, SDPP-DM was successfully applied to imaging and discriminating different endogenous bisulfite levels in normal and cancer cells of liver. More importantly, the ROS generation and cell viability tests showed the phototoxicity of SDPP-DM triggered by bisulfite, indicating the specific phototoxicity of SDPP-DM towards liver cancer cells than normal liver cells.

Increased Incidence of Dysmenorrhea in Women Exposed to Higher Concentrations of NO, NO2, NOx, CO, and PM2.5: A Nationwide Population-Based Study

Background: Air pollution is speculated to affect the reproductive health of women. However, a longitudinal association between exposure to air pollution and dysmenorrhea has not been identified, which this study aimed to examine this point.

Methods: Two nationwide databases, namely the Taiwan Air Quality Monitoring database and the Taiwan National Health Research Institutes database were linked. Women with a history of dysmenorrhea (International Classification of Disease, Ninth Revision, Clinical Modification code 625.3) before 2000 were excluded. All participants were followed from January 1, 2000 until the diagnosis of dysmenorrhea, withdrawal from National Health Insurance, or December 31, 2013. Furthermore, air pollutants were categorized into quartiles with three cut-off points (25th, 50th, and 75th percentiles). The Cox regression model was used to calculate the hazard ratios of dysmenorrhea.

Results: This study enrolled 296,078 women. The mean concentrations of yearly air pollutants were 28.2 (±12.6) ppb for nitric oxides (NO_x), 8.91 (±7.93) ppb for nitric oxide (NO), 19.3 (±5.49) ppb for nitrogen dioxide (NO₂), 0.54 (±0.18) ppm for carbon monoxide (CO), and 31.8 (±6.80) μg/m³ for PM_2.5. In total, 12,514 individuals developed dysmenorrhea during the 12-year follow-up. Relative to women exposed to Q1 concentrations of NO_x, women exposed to Q4 concentrations exhibited a significantly higher dysmenorrhea risk [adjusted hazard ratio (aHR)= 27.9, 95% confidence interval (CI) = 21.6–31.3]; similarly higher risk was found for exposure to NO (aHR = 16.7, 95% CI = 15.4–18.4) and NO₂ (aHR = 33.1, 95% CI = 30.9–37.4). For CO, the relative dysmenorrhea risk in women with Q4 level exposure was 28.7 (95% CI = 25.4–33.6). For PM_2.5, women at the Q4 exposure level were 27.6 times (95% CI = 23.1–29.1) more likely to develop dysmenorrhea than those at the Q1 exposure level.

Conclusion: Our results showed that women would have higher dysmenorrhea incidences while exposure to high concentrations of NO, NO₂, NO_x, CO, and PM_2.5.

Rational Development of a New Reaction-Based Ratiometric Fluorescent Probe with a Large Stokes Shift for Selective Detection of Bisulfite in Tap Water, Real Food Samples, Onion Tissues, and Zebrafish

Bisulfite (HSO₃^-) is usually widely added to tap water and food because it has antibacterial, bleaching, and antioxidant effects. However, its abnormal addition would cause a series of serious diseases related to it. Therefore, development of an effective method for HSO₃^- detection was of great significance to human health. In this work, a new reaction-based ratiometric fluorescent probe KQ-SO₂ was rationally designed, which could be used for the highly selective detection of HSO3^- in tap water, real food samples, onion tissues, and zebrafish. Specifically, a positively charged benzo[e]indolium moiety and a carbazole group through a condensation reaction resulted in KQ-SO₂, which displayed two well-resolved emission bands separated by 225 nm, fast response (1 min), and high selectivity and sensitivity toward HSO3^- upon undergoing the Michael addition reaction, as well as low cytotoxicity in vitro. In addition, KQ-SO₂ has been successfully applied for the detection of HSO₃^- in tap water, real food samples, onion tissues, and zebrafish with satisfactory results. We predict that KQ-SO₂ could be used as a powerful tool to reveal the relationship between HSO3^- and the human health.

A reversible near-infrared fluorescence probe for the monitoring of HSO3−/H2O2-regulated cycles in vivo

A near-infrared (NIR) fluorescent probe (XC) was constructed for the reversible detection of HSO3−/H2O2 in biosystems. The practical applications of XC were also demonstrated by the quantitative analysis of HSO3− in white wine and sugar samples.

Nanomedicines for Subcellular Targeting: The Mitochondrial Perspective

BACKGROUND

Over the past decade, there has been a surge in the number of mitochondrialactive therapeutics for conditions ranging from cancer to aging. Subcellular targeting interventions can modulate adverse intracellular processes unique to the compartments within the cell. However, there is a dearth of reviews focusing on mitochondrial nano-delivery, and this review seeks to fill this gap with regards to nanotherapeutics of the mitochondria.

METHODS

Besides its potential for a higher therapeutic index than targeting at the tissue and cell levels, subcellular targeting takes into account the limitations of systemic drug administration and significantly improves pharmacokinetics. Hence, an extensive literature review was undertaken and salient information was compiled in this review.

RESULTS

From literature, it was evident that nanoparticles with their tunable physicochemical properties have shown potential for efficient therapeutic delivery, with several nanomedicines already approved by the FDA and others in clinical trials. However, strategies for the development of nanomedicines for subcellular targeting are still emerging, with an increased understanding of dysfunctional molecular processes advancing the development of treatment modules. For optimal delivery, the design of an ideal carrier for subcellular delivery must consider the features of the diseased microenvironment. The functional and structural features of the mitochondria in the diseased state are highlighted and potential nano-delivery interventions for treatment and diagnosis are discussed.

CONCLUSION

This review provides an insight into recent advances in subcellular targeting, with a focus on en route barriers to subcellular targeting. The impact of mitochondrial dysfunction in the aetiology of certain diseases is highlighted, and potential therapeutic sites are identified.

A novel dual-function fluorescent probe for the rapid detection of bisulfite and hydrogen peroxide in aqueous solution and living cells

In this work, Hcy-OB, a novel hemicyanine-based biocompatible dual-function fluorescence probe for bisulfite and H₂O₂ detection is designed and synthesized. Based on a 1,4-addition reaction, Hcy-OB can be used for bisulfite detection with fast response, high sensitivity and low detection limit (120 nM). In addition, the probe is successfully applied to the detection of bisulfite in aqueous solution. Furthermore, Hcy-OB shows excellent performance for hydrogen peroxide detection with the oxidation of phenylboronic acid. Hcy-OB shows excellent selectivity to H₂O₂ over other interfering substances with detection limit of H₂O₂ is calculated to be 70 nM. Most importantly, due to its good cell membrane permeability and low cytotoxicity, Hcy-OB has been applied to monitor and image H₂O₂ in living cells and mice.

Sex difference in bronchopulmonary dysplasia of offspring in response to maternal PM2.5 exposure

The adverse effects of fine particulate matters (PM_2.5) on respiratory diseases start in utero. In order to investigate whether maternal PM_2.5 exposure could lead to bronchopulmonary dysplasia (BPD) in offspring, PM_2.5 was collected in Taiyuan, Shanxi, China during the annual heating period. Mice were mated and gestation day 0 (GD0) was considered the day on which a vaginal plug was observed. The plug-positive mice received 3 mg/kg b.w. PM_2.5 by oropharyngeal aspiration every other day starting on GD0 and throughout the gestation period. Offspring were sacrificed at postnatal days (PNDs) 1, 7, 14 and 21. We assessed some typical BPD-like symptoms in offspring. The results showed that maternal PM_2.5 exposure caused low birth weight, hypoalveolarization, decreased angiogenesis, suppressed production of secretory and surfactant proteins, and increased inflammation in the lungs of male offspring. However, maternal PM_2.5 exposure induced only hypoalveolarization and inflammation in the lungs of female offspring. Furthermore, these alterations were reversed during postnatal development. Our results demonstrated that maternal exposure to PM_2.5 caused reversible BPD-related consequences in offspring, and male offspring were more sensitive than females. However, these alterations were reversed during postnatal development.

The Effect of Sodium Metabisulphite on Apoptosis in the Experimental Model of Parkinson’s Disease

Background:

The aim of this study was to investigate the mechanisms underlying possible toxic effects of sulphite on neurodegeneration.

Methods:

Male Wistar rats were assigned to each of the four groups: Control (Control), Sulphite-treated (Sulphite), 6-hydroxydopamine (6-OHDA)-injected (6-OHDA), and sulphite-treated and 6-OHDA-injected (6-OHDA+Sulphite). Sodium metabisulphite was administered orally by gavage at a dose of 100 mg/kg/day for 45 days. Experimental PD was created stereotactically via the unilateral infusion of 6-OHDA into the medial forebrain bundle (MFB). Rotarod performances, plasma S-sulfonate levels, caspase-3 activities, Bax and Bcl-2 levels, tyrosine hydroxylase (TH) and cleaved caspase-3 double staining were investigated.

Results:

The rotarod test showed that the 6-OHDA-injected animals exhibited shorter time on the rod mile compared to the control group; however, there was no difference between 6-OHDA and 6-OHDA+Sulphite groups. Plasma levels of S-sulfonate in Sulphite and 6-OHDA+ Sulphite groups increased in contrast to their corresponding control groups. Caspase-3 enzyme activity increased in the 6-OHDA group whereas it did not in control. However, sulphite treatment did not affect these activity levels. Anti-apoptotic protein Bcl-2 concentration decreased, but the concentration of pro-apoptotic protein Bax increased in the 6-OHDA group compared to the control group. The expression of caspase-3 increased, while the number of tyrosine hydroxylase (TH)-positive neurons decreased in 6-OHDA group as compared to the control groups. However, sulphite treatment had no effect on these parameters.

Conclusion:

Sulphite is not a potentially aggravating factor for the activity of caspase-3 in a 6- OHDA-induced experimental model of Parkinson’s disease.

The Role of Cyclooxygenases-2 in Benzo(a)pyrene-Induced Neurotoxicity of Cortical Neurons

With the help of particulate matter, benzo(a)pyrene (BaP) has become a widely distributed environmental contaminant. In addition to the well-known carcinogenicity, a growing number of studies have focused on the neurotoxicity of BaP, especially on adverse neurobehavioral effects. However, the molecular modulating mechanisms remain unclear. In this paper, we confirmed that BaP exposure produced a neuronal insult via its metabolite benzo(a)pyrene diol epoxide (BPDE) on the primary cultured cortical neuron in vitro and mice in vivo models, and the effects were largely achieved by activating cyclooxygenases-2 (COX-2) enhancement. Also, the action of BaP on elevating COX-2 was initiated by BPDE firmly binding to the active pockets of COX-2, then followed by the production of prostaglandin E₂ (PGE₂) and upregulation of its EP2 and EP4 receptors, finally stimulating the cyclic adenosine monophosphate/protein kinase A (cAMP/PKA) signaling pathway. Our results reveal a mechanistic association underlying BaP exposure and increased risk for neurological dysfunction and clarify the ways to prevent and treat brain injuries in polluted environments.

Mechanisms underlying the stimulatory effect of inhaled sulfur dioxide on vagal bronchopulmonary C-fibres

KEY POINTS

Brief inhalation of SO₂ of concentration >500 p.p.m. triggered a pronounced stimulatory effect on vagal bronchopulmonary C-fibres in anaesthetized rats. This stimulatory effect was drastically diminished by a pretreatment with NaHCO₃ that raised the baseline arterial pH, suggesting a possible involvement of acidification of airway fluid and/or tissue generated by inhaled SO₂ . The stimulation was completely abolished by pretreatment with antagonists of both acid-sensing ion channels and transient receptor potential vanilloid type-1 receptors, indicating that this effect was caused by acid activation of these cation channels expressed in airway sensory nerves. This conclusion was further supported by the results obtained from studies in isolated rat vagal bronchopulmonary sensory neurones and also in the cough response to SO₂ inhalation challenge in awake mice. These results provide new insight into the underlying mechanism of harmful irritant effects in the respiratory tract caused by accidental exposure to a high concentration of SO₂ .

ABSTRACT

Inhalation of sulfur dioxide (SO₂ ) triggers coughs and reflex bronchoconstriction, and stimulation of vagal bronchopulmonary C-fibres is primarily responsible. However, the mechanism underlying this stimulatory effect is not yet fully understood. In this study, we tested the hypothesis that the C-fibre stimulation was caused by SO₂ -induced local tissue acidosis in the lung and airways. Single-unit activities of bronchopulmonary C-fibres in response to inhalation challenges of SO₂ (500-1500 p.p.m., 10 breaths) were measured in anaesthetized rats. Inhalation of SO₂ reproducibly induced a pronounced and sustained stimulation (lasting for 15-60 s) of pulmonary C-fibres in a concentration-dependent manner. This stimulatory effect was significantly attenuated by an increase in arterial pH generated by infusion of sodium bicarbonate (NaHCO₃ ), and completely abrogated by a combined pretreatment with amiloride (an antagonist of acid-sensing ion channels, ASICs) and AMG8910 (a selective antagonist of the transient receptor potential vanilloid type-1 receptor, TRPV1). Furthermore, in isolated rat vagal pulmonary sensory neurones, perfusion of an aqueous solution of SO₂ evoked a transient increase in the intracellular Ca²⁺ concentration; this response was also markedly diminished by a pretreatment with amiloride and AMG8910. In addition, inhalation of SO₂ consistently evoked coughs in awake mice; responses were significantly smaller in TRPV1^-/- mice than in wild-type mice, and almost completely abolished after a pretreatment with amiloride in TRPV1^-/- mice. These results suggested that the stimulatory effect of inhaled SO₂ on bronchopulmonary C-fibres was generated by acidification of fluid and/or tissue in the lung and airways, which activated both ASICs and TRPV1 expressed in these sensory nerves.

A mitochondria-targeting ratiometric fluorescent probe for the detection of sulfur dioxide in living cells

A mitochondria-targeting ratiometric fluorescent probe was developed for the detection of sulfur dioxide in living cells.

An effective biocompatible fluorescent probe for bisulfite detection in aqueous solution, living cells, and mice

Sulfur dioxide, an air pollutant, is easily hydrated to sulfites and bisulfites and extremely harmful to human health. On the other hand, endogenous sulfur dioxide is the fourth gasotransmitter. In view of the above, it is worth developing an effective method for the detection of these compounds. In this paper, a novel colorimetric fluorescent probe (Hcy-Mo), based on hemi-cyanine, for bisulfites is reported. Hcy-Mo shows excellent selectivity for bisulfites over various other species including cysteine, glutathione, CN⁻, and HS⁻, and undergoes 1,4-addition reactions at the C-4 atom of the ethylene group. The reaction can be completed in 30 s in a PBS buffer solution and displays high sensitivity (limit of detection is 80 nM) for bisulfites. Test paper experiments show that the probe can be used for bisulfite detection in aqueous solutions. In addition, Hcy-Mo exhibits excellent cell permeability and low cytotoxicity for the successful detection of bisulfites in living MDA-MB-231 cells and in living mice, implying that this probe would be of great benefit to biological researchers for investigating the detailed biological and pharmacological functions of bisulfites in biological systems.

Sulfur dioxide, an air pollutant, is easily hydrated to sulfites and bisulfites and extremely harmful to human health.

An ESIPT-Based Ratiometric Fluorescent Probe for Highly Sensitive and Rapid Detection of Sulfite in Living Cells

The novel ratiometric fluorescent probe HPQRB with an ESIPT effect based on Michael addition for highly sensitive and fast detection of sulfite in living HepG2 cells is reported. HPQRB can be easily synthesized by a two-step condensation reaction. HPQRB has a large emission shift (Δλ=116 nm), which is beneficial for fluorescence imaging research, and its sulfite-responsive site is based on a rhodamine-like structure with the emission peak at 566 nm, which decreases with increasing sulfite concentration. and its HPQ structure always has an ESIPT effect throughout the reaction process, keeping the emission peak at 450 nm as a self-reference. In particular, HPQRB has high selectivity for sulfite and responds quickly (within 30 s) with a low detection limit (44 nM). Furthermore, HPQRB has been successfully used for fluorescence imaging of sulfite in HepG2 cells, demonstrating the superior ability to detect sulfite under physiological conditions.

A Benzopyronin-Based Two-Photon Fluorescent Probe for Ratiometric Imaging of Lysosomal Bisulfite with Complete Spectral Separation

Bisulfite (HSO₃^-), which equilibrates with sulfite (SO₃^2-) and sulfur dioxide (SO₂) in aqueous media, can be produced endogenously during oxidation of hydrogen sulfide or sulfur-containing amino acids. Lysosomes, known as the scavengers of living cells, play a crucial role in the metabolic process, and bisulfite is often produced inside the lysosomes. Therefore, detection of bisulfite in lysosomes is a subject of significant interest. Herein, we disclose a lysosome-targeting, two-photon excitable, and ratiometric signaling (near-infrared/green) fluorescent probe that detects bisulfite through a fast 1,6-conjugate addition reaction. The probe shows excellent selectivity toward bisulfite over other biologically relevant species. Notably, the probe allows ratiometric fluorescence imaging of lysosomal bisulfite with complete spectral separation under one-photon as well as two-photon excitation conditions.

Gas-phase degradation of 2-butanethiol initiated by OH radicals and Cl atoms: kinetics, product yields and mechanism at 298 K and atmospheric pressure

Relative rate coefficients and product distribution of the reaction of 2-butanethiol (2butSH) with OH radicals and Cl atoms were obtained at atmospheric pressure and 298 K. The experiments were performed in a 480 L borosilicate glass photoreactor in synthetic air coupled to a long path "in situ" FTIR spectrometer. The rate coefficients obtained by averaging the values from different experiments were: k _OH = (2.58 ± 0.21) × 10^-11 cm³ per molecule per s and k _Cl = (2.49 ± 0.19) × 10^-10 cm³ per molecule per s. The kinetic values were compared with related alkyl thiols and homologous alkyl alcohols, where it was found that thiols react faster with both oxidants, OH radicals and Cl atoms. SO₂ and 2-butanone were the major products identified for the reactions of 2-butanethiol with OH radicals and Cl atoms. The product yield of the reaction of 2-butanethiol and OH radicals were (81 ± 2)%, and (42 ± 1)% for SO₂ and 2-butanone, respectively. For the reactions of 2-butanethiol with Cl atom, yields of SO₂ and 2-butanone were (59 ± 2)% and (39 ± 2)%, respectively. A degradation mechanism was proposed for the pathways that leads to formation of identified products. The product distribution observed indicated that the H-atom of the S-H group abstraction channel is the main pathway for the reaction of OH radicals and Cl atoms with 2-butanethiol.

A novel colorimetric and ratiometric fluorescent probe for sensing SO2 derivatives and their bio-imaging in living cells

We report a novel fluorescent probe HBN-TCF for the detection of SO2 derivatives. This probe exhibited near-infrared fluorescence emission with an excitation wavelength of 620 nm. After reacting with SO32-, the emission channel at 664 nm decreased, while the new strong emission channel at 482 nm increased (λex = 400 nm), with a large emission distance (Δλ = 182 nm) observed. This probe exhibited the rapid and selective detection of SO2 derivatives compared with other sulfur-containing species and featured a low detection limit (82 nM). This colorimetric and ratiometric fluorescent probe showed high selectivity and sensitivity for detecting SO2 derivatives. The probe was also successfully exploited for the fluorescence imaging of intracellular and exogenous SO2 derivatives in BEL-7402 cells.

A New Red-Emitting Fluorescence Probe for Rapid and Effective Visualization of Bisulfite in Food Samples and Live Animals

The development of new methods for rapid and effective detection of bisulfite (HSO₃^-) in food samples and imaging of HSO₃^- intake in animals is of significant importance due to the key roles of HSO₃^- in food quality assurance and community health. In this work, a new responsive fluorescence probe, EQC, is reported for the quantitative detection of HSO₃^- in food samples and visualization of HSO₃^- intake in animals. Upon addition of HSO₃^-, the UV-vis absorption and red emission of EQC were significantly decreased within 120 s. The changes in absorption and emission spectra of EQC were rationalized by theoretical computations. The proposed reaction mechanism of EQC with HSO₃^- was confirmed by high-resolution mass spectrometry (HRMS) and spectroscopic titration measurements. EQC has the advantages of high sensitivity, selectivity (a detection limit of 18.1 nM), and fast response toward HSO₃^-, which enable rapid and effective HSO₃^- detection in buffer solution. The practical applications of EQC were demonstrated by the detection of HSO₃^- in food samples and the imaging of HSO₃^- intake in live animals.

A chromenoquinoline-based two-photon fluorescent probe for the highly specific and fast visualization of sulfur dioxide derivatives in living cells and zebrafish

Sulfur dioxide (SO₂) derivatives play critical roles in various biological processes. Therefore, effective methods for monitoring SO₂ are of vital importance in bisulfite/sulfite biology. In this study, a two-photon (TP) imaging probe (CQ-SO₂) for detecting SO₂ derivatives was designed and constructed, based on the chromenoquinoline (CQ) fluorophore and a β-chlorovinyl aldehyde sensing moiety. The TP properties of the CQ derivatives were revealed for the first time in this study. This study enriched the biological application range of CQ derivatives and also provided a new choice for the development of TP dyes. In particular, the CQ-SO₂ probe exhibited a fast response time (about 5 s), low detection limit (16 nM) and ultrahigh specificity towards SO₂ derivatives. Furthermore, the probe was successfully applied to the highly specific TP bioimaging of SO₂ derivatives in living cells and zebrafish.

Catalytic conversions of atmospheric sulfur dioxide and formation of acid rain over mineral dusts: Molecular oxygen as the oxygen source

Sulfur dioxide (SO₂) ranks as a major air pollutant and is likely to generate acid rain. When molecular oxygen is the oxygen source, the regular surfaces of gibbsite (one of the most abundant mineral dusts) show no reactivity for SO₂ conversions to H₂SO₄, while the partially dehydrated (100) surface with coordination-unsaturated Al sites becomes catalytically effective. Because of the easy availability of molecular oxygen, results manifest that acid rain can form under all atmospheric conditions and may account for the high conversion ratio of atmospheric SO₂. The (100) and (001) surfaces show divergent catalytic effects, and hydrolysis is always the rate-limiting step. Path A (hydrolysis and then oxidation) is preferred for (100) surface, whereas a third path with obviously lower activation barriers is presented for (001) surface, which is non-existent for (100) surface. Atomic oxygen originating from the dissociation of molecular oxygen is catalytically active for (100) surface, while the active site of (001) surface fails to be recovered, suggesting that SO₂ conversions over gibbsite surfaces are facet-controlled. This work also offers an environmentally friendly route for production of H₂SO₄ (one of the essential compounds in chemical industry), directly using molecular oxygen as the oxygen source.

A real-time ratiometric fluorescent probe for imaging of SO2 derivatives in mitochondria of living cells

A real-time ratiometric fluorescent probe (IN-CZ) for highly selective detection of sulfite was designed and synthesized, which is based on modulating the intramolecular charge transfer (ICT) of the hemicyanine dye platform. The mechanism of using the probe is mainly through the Michael addition that occurs between IN-CZ and sulfite with a detection limit of 2.99 × 10⁻⁵ M. IN-CZ displays a fast response (within 1 minute) and is highly selective for SO₃²⁻/HSO₃⁻ over ROS, biologically relevant ions, biological mercaptans and other reactive species. More importantly, IN-CZ was suitable for ratiometric fluorescence imaging in living cells, by real-time monitoring of SO₃²⁻/HSO₃⁻ changes in mitochondria targeted in living cells.

A real-time ratiometric fluorescent probe (IN-CZ) for highly selective detection of sulfite was designed and synthesized, which is based on modulating the intramolecular charge transfer of the hemicyanine dye platform.

Mitochondrial directed ratiometric fluorescent probe for quantitive detection of sulfur dioxide derivatives

A good biocompatibility fluorescence probe for imaging of sulfur dioxide derivatives in cancer cells.

Catalytic effect of (H2O)n (n = 1–3) clusters on the HO2 + SO2 → HOSO + 3O2 reaction under tropospheric conditions

The HO₂ + SO₂ → HOSO + ³O₂ reaction without and with (H₂O)n (n = 1–3) have been investigated using CCSD(T)/CBS//M06-2X/aug-cc-pVTZ methods, and canonical variational transition state theory with small curvature tunneling.

Maternal exposure to NO2 enhances airway sensitivity to allergens in BALB/c mice through the JAK-STAT6 pathway

Previous studies have indicated that nitrogen dioxide (NO₂) exposure could increase airway sensitivity to allergens for children. Recently, fetal stress was proposed as a crucial factor for allergic airway response occurring in offspring. Considering that there is inadequate evidence linking maternal NO₂ exposure to offspring airway sensitivity to allergens, pregnant Balb/c mice were exposed daily to 2.5 ppm NO₂ throughout the gestation period; then, the offspring were challenged to an allergen (ovalbumin, OVA) to evaluate airway sensitivity. For air + saline group and air + OVA group, offspring mice were maternally exposed to clean air followed by treatment with saline and OVA, respectively, in adulthood. For NO₂ + saline group and NO₂ + OVA group, offspring mice were maternally exposed to NO₂ followed by treatment with saline and OVA, respectively, in adulthood. The results showed that maternal NO₂ exposure increased the level of OVA-immunoglobulin (Ig) E in serum and caused airway hyper-responsiveness and pathological changes in offspring. Furthermore, maternal NO₂ exposure altered the expression of pro-inflammatory factors and impaired the T helper (Th) 1/Th2 balance. In addition, janus kinase)-signal transducer and activator of transcription 6 pathway participated in OVA-induced airway sensitivity of offspring. Our study showed that the potential risk of airway sensitivity to allergens in offspring is enhanced by maternal NO₂ exposure and proposed a possible mechanism for preventing, alleviating, and evaluating the outcomes in polluted environments.

A Novel Colorimetric Fluorescent Probe for SO₂ and Its Application in Living Cells Imaging

A novel chromenylium-based fluorescent probe was exploited for sulphur dioxide (SO₂) detecting. The probe displayed a remarkable fluorescence turn-on response towards SO₂ based on the nucleophilic addition reaction to the carbon-carbon double bond with 105 nm Stock shift. The probe was successfully applied for the quantification of SO₂.The linear detection range was from 0-160 μM with the detection limit as low as 99.27 nM. It also exhibited high selectivity for SO₂ than other reactive species and amino acids. Furthermore, cell staining experiments indicated that the probe was cell membrane permeable and could be used for high-performance imaging of SO₂ in living cells. The superior properties of the probe made it highly promising for use in chemical and biological applications.

Chronic voluntary oral methamphetamine induces deficits in spatial learning and hippocampal protein kinase Mzeta with enhanced astrogliosis and cyclooxygenase-2 levels

Methamphetamine (MA) is an addictive drug with neurotoxic effects on the brain producing cognitive impairment and increasing the risk for neurodegenerative disease. Research has focused largely on examining the neurochemical and behavioral deficits induced by injecting relatively high doses of MA [30 mg/kg of body weight (bw)] identifying the upper limits of MA-induced neurotoxicity. Accordingly, we have developed an appetitive mouse model of voluntary oral MA administration (VOMA) based on the consumption of a palatable sweetened oatmeal mash containing a known amount of MA. This VOMA model is useful for determining the lower limits necessary to produce neurotoxicity in the short-term and long-term as it progresses over time. We show that mice consumed on average 1.743 mg/kg bw/hour during 3 hours, and an average of 5.23 mg/kg bw/day over 28 consecutive days on a VOMA schedule. Since this consumption rate is much lower than the neurotoxic doses typically injected, we assessed the effects of long-term chronic VOMA on both spatial memory performance and on the levels of neurotoxicity in the hippocampus. Following 28 days of VOMA, mice exhibited a significant deficit in short-term spatial working memory and spatial reference learning on the radial 8-arm maze (RAM) compared to controls. This was accompanied by a significant decrease in memory markers protein kinase Mzeta (PKMζ), calcium impermeable AMPA receptor subunit GluA2, and the post-synaptic density 95 (PSD-95) protein in the hippocampus. Compared to controls, the VOMA paradigm also induced decreases in hippocampal levels of dopamine transporter (DAT) and tyrosine hydroxylase (TH), as well as increases in dopamine 1 receptor (D1R), glial fibrillary acidic protein (GFAP) and cyclooxygenase-2 (COX-2), with a decrease in prostaglandins E2 (PGE2) and D2 (PGD2). These results demonstrate that chronic VOMA reaching 146 mg/kg bw/28d induces significant hippocampal neurotoxicity. Future studies will evaluate the progression of this neurotoxic state.

A ratiometric fluorescence probe for rapid detection of mitochondrial SO2 derivatives

In this study, we report a fluorescent probe (CBT) for detecting SO₂ derivatives in ratiometric fluorescence manner.

Exhaled Breath Markers for Nonimaging and Noninvasive Measures for Detection of Multiple Sclerosis

Multiple sclerosis (MS) is the most common chronic neurological disease affecting young adults. MS diagnosis is based on clinical characteristics and confirmed by examination of the cerebrospinal fluids (CSF) or by magnetic resonance imaging (MRI) of the brain or spinal cord or both. However, neither of the current diagnostic procedures are adequate as a routine tool to determine disease state. Thus, diagnostic biomarkers are needed. In the current study, a novel approach that could meet these expectations is presented. The approach is based on noninvasive analysis of volatile organic compounds (VOCs) in breath. Exhaled breath was collected from 204 participants, 146 MS and 58 healthy control individuals. Analysis was performed by gas-chromatography mass-spectrometry (GC-MS) and nanomaterial-based sensor array. Predictive models were derived from the sensors, using artificial neural networks (ANNs). GC-MS analysis revealed significant differences in VOC abundance between MS patients and controls. Sensor data analysis on training sets was able to discriminate in binary comparisons between MS patients and controls with accuracies up to 90%. Blinded sets showed 95% positive predictive value (PPV) between MS-remission and control, 100% sensitivity with 100% negative predictive value (NPV) between MS not-treated (NT) and control, and 86% NPV between relapse and control. Possible links between VOC biomarkers and the MS pathogenesis were established. Preliminary results suggest the applicability of a new nanotechnology-based method for MS diagnostics.

Two-Photon and Deep-Red Emission Ratiometric Fluorescent Probe with a Large Emission Shift and Signal Ratios for Sulfur Dioxide: Ultrafast Response and Applications in Living Cells, Brain Tissues, and Zebrafishes

Sulfur dioxide (SO₂) is a dangerous environmental pollutant. Excessive intake of it may cause some respiratory diseases and even lung cancer. The development of effective methods for detection of SO₂ is of great importance for the environment and physiology. Herein, we have designed and synthesized a novel two-photon (TP) and deep-red emission ratiometric fluorescent probe (CP) for detection of SO₂. Notably, the novel probe CP exhibited ultrafast response to SO₂ in less than 5 s and displayed a great emission shift (195 nm) and a large emission signal ratio variation (enhancement from 0.1347 to 100.14). In addition, the unique probe was successfully employed for imaging SO₂ not only in the mitochondria of living cells but also in brain tissues and zebrafishes.