Simple cyclic chalcone dye with multiple optical functions: Piezochromism and lysosomes staining.

Both artificially synthesized and naturally occurring cyclic chalcones have been widely studied for their excellent biological activities. However, research on its photophysical properties is still limited. In the present study, we designed and synthesized a small molecule fluorescent dye based on the ICT effect, using dimethylamino as the electron-donating group and carbonyl as the electron withdrawing group, and investigated its photophysical properties in depth. Although YB is a simple small molecule, it exhibits significant piezochromic properties. The fluorescence of YB can change from green to yellow through grinding. After solvent fumigation, the fluorescence reverts to green. Furthermore, YB was used successfully in the lysosomal targeting. This study expands the research on the photophysical properties of cyclic chalcone and give richness to application of cyclic chalcone compounds.

Feasibility of low-intensity ultrasound treatment with hydroxylamine to accelerate the initiation of partial nitrification and allow operation under intermittent aeration.

Partial nitrification is a key aspect of efficient nitrogen removal, although practically it suffers from long start-up cycles and unstable long-term operational performance. To address these drawbacks, this study investigated the effect of low intensity ultrasound treatment combined with hydroxylamine (NH2OH) on the performance of partial nitrification. Results show that compared with the control group, low-intensity ultrasound treatment (0.10 W/mL, 15 min) combined with NH2OH (5 mg/L) reduced the time required for partial nitrification initiation by 6 days, increasing the nitrite accumulation rate (NAR) and ammonia nitrogen removal rate (NRR) by 20.4% and 6.7%, respectively, achieving 96.48% NRR. Mechanistic analysis showed that NH2OH enhanced ammonia oxidation, inhibited nitrite-oxidizing bacteria (NOB) activity and shortened the time required for partial nitrification initiation. Furthermore, ultrasonication combined with NH2OH dosing stimulated EPS (extracellular polymeric substances) secretion, increased carbonyl, hydroxyl and amine functional group abundances and enhanced mass transfer. In addition, 16S rRNA gene sequencing results showed that ultrasonication-sensitive Nitrospira disappeared from the ultrasound + NH2OH system, while Nitrosomonas gradually became the dominant group. Collectively, the results of this study provide valuable insight into the enhancement of partial nitrification start-up during the process of wastewater nitrogen removal.

Highly selective and sensitive benzopyran-based fluorescent probes for imaging exogenous and endogenous peroxynitrite.

Peroxynitrite is widely present in organisms and closely related to many pathophysiological functions. Therefore, it is of great physiological significance to develop capable probes for detecting ONOO-. In this work, a novel fluorescent probe B-Ch was designed based on the intramolecular charge transfer (ICT) effect. By means of molecular engineering, the replacement from diethylamine group to hydroxyl group has improved the detection sensitivity of the probe. After the addition of ONOO-, the solution color and fluorescence showed noticeable changes, which were visible to the naked eye. The probe showed excellent advantages: visualization, good selectivity, low sensitivity (22.4 nM), good stability and biocompatibility, exogenous and endogenous imaging of ONOO- in HeLa cells.

A coumarin-based fluorescent probe: single-wavelength excitation, discrimination of Cys/Hcy and GSH by naked eyes.

Biothiols mainly include cysteine (Cys), homocysteine (Hcy) and glutathione (GSH), which play an important role in life activities and abnormal changes in their concentrations are closely related to certain diseases. Therefore, the quantitative tracking and analysis of biothiols in living organisms has become a hot research topic in recent years. In this work, a coumarin-based fluorescent probe COUN was designed and synthesized for the comparable color recognition of Cys/Hcy and GSH by introducing the phenylethynyl group as the recognition site of biothiols, which showed significant fluorescence enhancement and green fluorescence under the UV light at 365 nm. The probe specifically recognized Hcy, showing 40-fold fluorescence enhancement and strong green fluorescence at 492 nm. Moreover, there was a good linear relationship between the fluorescence intensity of the probe and certain concentrations of Cys/Hcy and GSH, with detection limits of 36.6 nM, 86.4 nM, and 174 nM, respectively. The recognition mechanism of COUN to distinguish Cys/Hcy and GSH was studied by TDDFT calculations. More importantly, COUN was successfully used for imaging biothiols in living cells. The results showed that this probe could provide an effective contribution to the understanding of the role of biothiols, especially Hcy.

The coumarin-pyrazole dye for detection of hydrogen sulfide in cells.

Fluorescent probes for H2S are often interfered by other thiols. In this work, a coumarin-pyrazole dye with 2,4-dinitrosulfonyl group was designed for the detection of H2S. The probe exhibits weak fluorescence in water due to the photo induced electron transfer (PET) by 2,4-dinitrosulfonyl. After the sulfonyl group is cleaved off by H2S, strong fluorescence appears. The probe can specifically detect H2S without being interfered by other biological thiols, and shows a wide applicable pH range, low detection and wide detection range. The excellent detection properties of the probe can also be used to detect endogenous and exogenous H2S in cells. In addition, the probes can be made into portable test paper for the detection of H2S in solutions and can detect H2S in different water samples.

Monitoring intracellular pH using a hemicyanine-based ratiometric fluorescent probe.

Monitoring intracellular pH using ratiometric fluorescent probes can provide further insights into various biological processes including many diseases. Although ratiometric fluorescent probes with dual emission can efficiently exclude interferences (probe concentration, instrumental efficiency, and environmental conditions) compared with traditional off-on fluorescent probes, development of pH-responsive fluorescent probes with dual emission remains relatively unexplored and challenging. Herein we reported a new hemicyanine-based ratiometric fluorescent probe 1 with a hydroxyl group. The probe 1 exhibits dual emission and shows a real-time and selective fluorescence response to micro-environmental pH conditions in a range of 6.0 âˆ¼ 8.0. Further studies revealed that 1 could exclusively enter and accumulate into mitochondria and monitor the pH micro-environmental conditions through fluorescence imaging in HepG2 cells. We suggest that this probe might be used as a probe to elucidate the role of pH in many physiological processes.

Enhancing probe's sensitivity for peroxynitrite through alkoxy modification of dicyanovinylchromene.

An intramolecular charge transfer (ICT)-based fluorescent probe P-ONOO- was synthesized to detect ONOO-. After responding to peroxynitrite, the dicyano-vinyl group of P-ONOO- generates the aldehyde group, emitting strong green fluorescence accompanied by quenching of the yellow fluorescence. According to the calculated Fukui function, the modification of the alkoxy group can enhance the f+ of P-ONOO-, which can enhance the probe's nucleophilic addition reactivity with ONOO-. It has been experimentally verified that P-ONOO- shows fast response (within 30 s), excellent sensitivity (the detection limit = 10.4 nM), and good selectivity towards ONOO-. Additionally, the probe P-ONOO- has high membrane permeability and good biocompatibility, which can image endogenous ONOO- and exogenous ONOO- in HeLa cells.

Single-cell transcriptomic atlas reveals distinct immunological responses between COVID-19 vaccine and natural SARS-CoV-2 infection.

To control the ongoing coronavirus disease-2019 (COVID-19) pandemic, CoronaVac (Sinovac), an inactivated vaccine, has been granted emergency use authorization by many countries. However, the underlying mechanisms of the inactivated COVID-19 vaccine-induced immune response remain unclear, and little is known about its features compared to (Severe acute respiratory syndrome coronavirus 2) SARS-CoV-2 infection. Here, we implemented single-cell RNA sequencing (scRNA-seq) to profile longitudinally collected PBMCs (peripheral blood mononuclear cells) in six individuals immunized with CoronaVac and compared these to the profiles of COVID-19 infected patients from a Single Cell Consortium. Both inactivated vaccines and SARS-CoV-2 infection altered the proportion of different immune cell types, caused B cell activation and differentiation, and induced the expression of genes associated with antibody production in the plasma. The inactivated vaccine and SARS-COV-2 infection also caused alterations in peripheral immune activity such as interferon response, inflammatory cytokine expression, innate immune cell apoptosis and migration, effector T cell exhaustion and cytotoxicity, however, the magnitude of change was greater in COVID-19 patients, especially those with severe disease, than in immunized individuals. Further analyses revealed a distinct peripheral immune cell phenotype associated with CoronaVac immunization (HLA class II upregulation and IL21R upregulation in naïve B cells) versus SARS-CoV-2 infection (HLA class II downregulation and IL21R downregulation in naïve B cells from severe disease individuals). There were also differences in the expression of important genes associated with proinflammatory cytokines and thrombosis. In conclusion, this study provides a single-cell atlas of the systemic immune response to CoronaVac immunization and revealed distinct immune responses between inactivated vaccines and SARS-CoV-2 infection.

Proteomic and Metabolomic Signatures Associated With the Immune Response in Healthy Individuals Immunized With an Inactivated SARS-CoV-2 Vaccine.

CoronaVac (Sinovac), an inactivated vaccine for SARS-CoV-2, has been widely used for immunization. However, analysis of the underlying molecular mechanisms driving CoronaVac-induced immunity is still limited. Here, we applied a systems biology approach to understand the mechanisms behind the adaptive immune response to CoronaVac in a cohort of 50 volunteers immunized with 2 doses of CoronaVac. Vaccination with CoronaVac led to an integrated immune response that included several effector arms of the adaptive immune system including specific IgM/IgG, humoral response and other immune response, as well as the innate immune system as shown by complement activation. Metabolites associated with immunity were also identified implicating the role of metabolites in the humoral response, complement activation and other immune response. Networks associated with the TCA cycle and amino acids metabolic pathways, such as phenylalanine metabolism, phenylalanine, tyrosine and tryptophan biosynthesis, and glycine, serine and threonine metabolism were tightly coupled with immunity. Critically, we constructed a multifactorial response network (MRN) to analyze the underlying interactions and compared the signatures affected by CoronaVac immunization and SARS-CoV-2 infection to further identify immune signatures and related metabolic pathways altered by CoronaVac immunization. These results help us to understand the host response to vaccination of CoronaVac and highlight the utility of a systems biology approach in defining molecular correlates of protection to vaccination.

A hemicyanine-based near-infrared fluorescent probe for vapor-phase hydrazine detection and bioimaging in a complete aqueous media.

A novel near-infrared fluorescent probe CyOE based on hemicyanine dye containing acetyl as a recognition site is reported. The probe CyOE shows high selectivity and sensitivity (LOD = 82 nM, 2.58 ppb), as well as good water solubility and quantitative detectability of hydrazine in the concentration range of 0-75 µM (R2 = 0.993). Moreover, CyOE has a significant increase in fluorescence at 735 nm with the addition of N2H4, which provides a rapid, colorimetric and gas-phase detection method for N2H4 in both aqueous solution and real water samples. In addition, CyOE is successfully utilized to visualize hydrazine in cells with low cytotoxicity and high cell permeability.

High-efficiency treatment of electroless nickel plating effluent using core-shell MnFe2O4-C@Al2O3 combined with ozonation: Performance and mechanism.

Heterogeneous catalytic ozonation (HCO) has been widely applied for the treatment of wastewater. In order to maintain the structural stability and surface catalytic activity of heterogeneous catalysts during the HCO treatment of electroless nickel plating effluent (ENPE), a MnFe2O4-C@Al2O3 catalyst with a core-shell structure was synthesized. MnFe2O4-C@Al2O3 was characterized and applied in the removal of total nickel (TNi) and organic contaminants from actual ENPE, using a coupled system of HCO combined with a magnetic dithiocarbamate chelating resin (MnFe2O4-C@Al2O3/O3-MDCR). Results show that embedding Al2O3 with C and MnFe2O4 significantly increased the TNi removal efficiency (99.3%), enhanced the O3-utilization efficiency and improved the generation of reactive oxygen species (ROS). The reaction rate (k = 0.7641 min-1) and O3-utilization efficiency established for TNi removal (ΔTNi/ΔO3 =0.221) by the MnFe2O4-C@Al2O3/O3-MDCR system, were 220% and 140% higher than the Al2O3/O3-MDCR system, respectively. Catalytic mechanism analysis demonstrated that surface hydroxyl groups, oxygen vacancy, metals, the carbon surface and its functional groups, can all potentially serve as catalytic active sites, with 1O2 and •OH considered to the predominant ROS. Overall, these findings verify that the synthesized MnFe2O4-C@Al2O3 catalyst possesses excellent catalytic capabilities and outstanding structural stability, making it suitable for practical application in the treatment of wastewater effluent.

Efficient deep blue emission by 4-styrylbenzonitrile derivatives in solid state: Synthesis, aggregation induced emission characteristics and crystal structures.

Organic fluorescent molecules with π-conjugated system have shown great importance in numerous applications including bioimaging and optoelectronics. Planar aggregation-induced emissive (AIE) organic compounds with efficient solid-state luminescence are rarely developed and urgently needed in various applications. In this work, highly planar 4-styrylbenzonitrile derivatives have been synthesized. Most of these compounds show strong AIE properties with hundred-fold fluorescent enhancement. Moreover, these molecules are deep blue emissive in solid state, exhibiting good to excellent fluorescence quantum efficiency. The single crystal analysis shows that adjacent molecules could form special J-type aggregation. The intramolecular rotations are efficiently restricted by various noncovalent interactions. These molecular arrangements could be essential for the observed strong emission in aggregated and solid state. This work has paved a new path to efficient AIE-active organic emitters with highly planar conformations from 4-styrylbenzonitrile structure.

A Novel Real-Time Reverse Transcription Loop-Mediated Isothermal Amplification Detection Platform: Application to Diagnosis of COVID-19.

The ongoing Corona virus disease (COVID-19) outbreak has become a huge global health concern. Here, we reported a novel detection platform based on the loop-mediated isothermal amplification (LAMP), termed real-time reverse transcription LAMP (rRT-LAMP) and applied it for the diagnosis of COVID-19 (COVID-19 rRT-LAMP). rRT-LAMP integrates reverse transcription, LAMP amplification, restriction endonuclease cleavage and real-time fluorescence detection into one-pot reaction, and facilitates the diagnosis of COVID-19 at 64°C for only 35 min. The ORF1ab (opening reading frame 1a/b) and NP (nucleoprotein) genes of SARS-CoV-2 were detected for diagnosing COVID-19. The limit of detection (LoD) of COVID-19 rRT-LAMP assay was 14 copies (for each marker) per vessel, and no positive results were obtained from non-SARS-CoV-2 templates. To demonstrate its feasibility, a total of 33 oropharynx swab samples collected from COVID-19 patients also were diagnosed as SARS-CoV-2 infection using COVID-19 rRT-LAMP protocol. No cross-reactivity was yielded from 41 oropharynx swab samples collected from non-COVID-19 patients. These data suggesting that the COVID-19 rRT-LAMP assay is a potential detection tool for the diagnosis of SARS-CoV-2 infection in clinical, field and disease control laboratories, and will be valuable for controlling the COVID-19 epidemic.

A mitochondria-targeted fluorescent probe for real-time imaging SO2/H2O2.

Studies have shown that changes in the redox state of cells might be closely related to pathological and physiological processes. Sulfur dioxide and hydrogen peroxide, as a significant redox couple in living cells, are endogenously produced by cells. Here, we report a long-wavelength fluorescent probe to reversibly monitor sulfur dioxide and hydrogen peroxide. This probe (NBD) displayed high selectivity and sensitivity, which could be accumulated in mitochondria for real-time imaging of SO2/H2O2. These results indicated that NBD would be an ideal tool for monitoring the redox cycle state in living cells.

A coumarin-based portable fluorescent probe for rapid turn-on detection of amine vapors.

Amines are widely used in many fields including agriculture, dyes, medicine and food processing. However, volatile amine vapors could initiate acute and serious damage to human bodies. Thus, highly efficient detection of volatile amine vapors has great importance for academic research as well as practical application. In this work, a turn-on type fluorescent sensor BZCO has been developed, which could be used to detect volatile amine vapors. The portable BZCO sensor can be easily prepared through immersing filter paper into its CH2Cl2 solution and then evaporating it to dryness. This paper-based amine vapor sensor exhibits high sensitivity with a relatively low detection limit at 3.82 ppm. It also has good selectivity for discriminating amine vapors from volatile organic solvents. The detection mechanism has been confirmed by UV-vis spectral analysis. The practical applications of this paper-based BZCO sensor, such as detection of food spoilage and fluorescent security ink, have been investigated. This work has developed a new fluorescent sensor BZCO, which has broad applications in various fields, including amine gas detection, security and anti-counterfeiting materials.

A seroepidemiological investigation of Lyme disease in Qiongzhong County, Hainan Province in 2019-2020.

BACKGROUND: The incidence and prevalence of Lyme disease are expanding and rising, respectively, which constitutes a worldwide public health problem. The present study aimed to investigate the prevalence of Lyme disease (LD) in Qiongzhong County, Hainan, and to determine the LD infection level in the local population, so as to provide evidence for further local LD surveillance as well as effective prevention and treatment measures. METHODS: A total of 252 serum samples were collected from cases with suspected LD in Qiongzhong County, including 159 and 93 cases with joint and neurological symptoms, respectively. The serum samples were preliminarily screened for LD antibodies by indirect immunofluorescent assay (IFA). Western Blot (WB) was used to confirm the diagnosis of IFA positive serum samples. RESULTS: Of the 252 serum samples, 39 tested positive by indirect immunofluorescence, translating to a positive rate of 15.48%. Of these 39 positive serum samples, western blot testing confirmed 28 to be positive for LD antibodies, representing a positive rate of 11.11%. LD spirochete infection was found in individuals of different ages, with the positive rate being highest among those aged ≤20 and ≥81 years old (22.22% in both groups). The positive rate of LD antibody detection in men was 16.89%, which was higher than the rate of 13.46% seen in women; however, the difference was not statistically significant. The positive rate of LD antibody detection using the 2-step testing method was 10.06% in patients with joint symptoms, which was slightly lower than the positive rate among individuals with neurological symptoms. CONCLUSIONS: Our results confirm the presence of LD among the population of Qiongzhong County, Hainan. LD surveillance should be carried out to actively prevent and treat LD in the locality. Local doctors should also consider the possibility of LD when diagnosing and treating patients with arthritis and neurological diseases.

A highly-sensitive "turn on" probe based on coumarin ß-diketone for hydrazine detection in PBS and living cells.

Herein, a new "turn on" fluorescent probe C-1 is developed to specifically detect hydrazine using coumarin nucleus as the fluorophore and ß-diketone as the recognition group. The probe shows high selectivity towards hydrazine over other common ions and amine-containing species, as well as good water solubility and quantitative detectability of hydrazine in concentration range of 1-200 µM. The detection limit is as low as 1.89 ppb, which is lower than the threshold set by EPA (10 ppb). Probe-coated filter papers are confirmed to detect gaseous hydrazine successfully through obvious fluorescence color changes. In addition, the probe has been verified to detect hydrazine in actual water environment and living cells.

Multiplex reverse transcription loop-mediated isothermal amplification combined with nanoparticle-based lateral flow biosensor for the diagnosis of COVID-19.

The ongoing global pandemic (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has become a huge public health issue. Hence, we devised a multiplex reverse transcription loop-mediated isothermal amplification (mRT-LAMP) coupled with a nanoparticle-based lateral flow biosensor (LFB) assay (mRT-LAMP-LFB) for diagnosing COVID-19. Using two LAMP primer sets, the ORF1ab (opening reading frame 1a/b) and N (nucleoprotein) genes of SARS-CoV-2 were simultaneously amplified in a single-tube reaction, and detected with the diagnosis results easily interpreted by LFB. In presence of FITC (fluorescein)-/digoxin- and biotin-labeled primers, mRT-LAMP produced numerous FITC-/digoxin- and biotin-attached duplex amplicons, which were determined by LFB through immunoreactions (FITC/digoxin on the duplex and anti-FITC/digoxin on the test line of LFB) and biotin/treptavidin interaction (biotin on the duplex and strptavidin on the polymerase nanoparticle). The accumulation of nanoparticles leaded a characteristic crimson band, enabling multiplex analysis of ORF1ab and N gene without instrumentation. The limit of detection (LoD) of COVID-19 mRT-LAMP-LFB was 12 copies (for each detection target) per reaction, and no cross-reactivity was generated from non-SARS-CoV-2 templates. The analytical sensitivity of SARS-CoV-2 was 100% (33/33 oropharynx swab samples collected from COVID-19 patients), and the assay's specificity was also 100% (96/96 oropharynx swab samples collected from non-COVID-19 patients). The total diagnostic test can be completed within 1 h from sample collection to result interpretation. In sum, the COVID-19 mRT-LAMP-LFB assay is a promising tool for diagnosing SARS-CoV-2 infections in frontline public health field and clinical laboratories, especially from resource-poor regions.

A diazabenzoperylene derivative as ratiometric fluorescent probe for cysteine with super large Stokes shift.

Biothiols, including cysteine (Cys), homocysteine (Hcy), and glutathione (GSH), play key roles in biological processes, and detecting such thiols selectively is critical for understanding functions of biothiols. In this work, a pyridazine annelated perylene-based fluorescent probe PAPC is synthesized for highly selective detection of Cys. PAPC exhibits strong blue emission in PBS, while the red emission at 605 nm can be observed in the presence of Cys. The probe PAPC shows ratiometric fluorescence (I605/I460) detection of Cys with wide linear range of 1-120 µM and low detection limit of 0.19 µM. Super large Stokes shift (170 nm) and ratiometric fluorescence endow the probe low background signal. The discrimination of Cys over Hcy and GSH can be achieved through the difference of the ratiometric fluorescence. In addition, the probe has been proven to track Cys in real samples such as urine and HeLa cells. Therefore, PAPC probe is a promising candidate for detecting Cys in practical application. Graphical abstract.

Tetrahydro[5]helicene fused nitrobenzoxadiazole as a fluorescence probe for hydrogen sulfide, cysteine/homocysteine and glutathione.

Biological thiols including homocysteine (Hcy), cysteine (Cys), hydrogen sulfide (H2S) and glutathione (GSH) play crucial roles in various pathological and physiological processes. The development of optical probes for biothiols has been an active research area in recent years. Herein, a new turn-on fluorescence probe (HD-NBD) was designed and synthesized by fusing tetrahydro[5]helicene and 7-nitro-2,1,3-benzoxadiazole (NBD) for simultaneous discrimination of Hcy/Cys, H2S and GSH in aqueous solution. This probe is able to show unique absorbance enhancement at 548 nm for H2S and additional fluorescence enhancement at 536 nm only for Cys/Hcy, which can be used to discriminate H2S, Cys/Hcy and GSH simultaneously. In addition, HD-NBD also shows low background without any self-fluorescence, as well as high selectivity toward common biothiols. The low detection limits of this probe are about 0.15 µM for Hcy with a wide linear range (1-80 µM), 0.36 µM for Cys (linear range: 1-45 µM), 0.79 µM for H2S (linear range: 1-80 µM) and 4.44 µM for GSH (linear range: 1-60 µM). Moreover, HD-NBD can identify Hcy/Cys, H2S from GSH and other amino acids with high sensitivity and selectivity, therefore it could be used for detecting endogenous and exogenous Hcy/Cys under biological condition.