Enhancing Respiratory Symptoms: The Impact of Acupoint Application Combined with Back Tapping in Patients with Expectoration and Wheezing.

Background: Expectoration and wheezing are prevalent symptoms of respiratory diseases. Acupoint application and back tapping have shown effectiveness in alleviating cough, wheezing, and associated symptoms. Objective: This study aimed to investigate the influence of combining acupoint application with back tapping in patients experiencing expectoration and wheezing. Design: A retrospective study design was employed. Setting: The study was conducted at Lujiang County Hospital of Traditional Chinese Medicine. Participants: A total of 96 patients presenting with expectoration and wheezing between January 2019 and June 2021 were randomly allocated into an observation group (n=48) and a control group (n=48). Interventions: The control group received an acupoint application using white mustard seed. In contrast, the observation group received additional back-tapping along meridians. Primary Outcome Measures: (1) Clinical efficacy; (2) traditional Chinese medicine (TCM) syndrome scores; (3) levels of inflammatory factors; (4) blood gas analysis indexes; (5) pulmonary function indexes; and (6) quality of life was assessed. Results: Following treatment, the observation group exhibited superior clinical efficacy (P < .05), reduced traditional Chinese medicine syndrome scores for cough, expectoration, and wheezing (P < .05), more pronounced improvements in inflammatory factor levels (P < .05), blood gas analysis indexes (P < .05), pulmonary function indexes (P < .05), and higher quality of life (P < .05) compared to the control group. Conclusions: Combining acupoint application with back tapping effectively alleviated symptoms and inflammatory responses, improved blood gas and pulmonary function, and enhanced the quality of life in patients experiencing expectoration and wheezing.

An electrochemical determination strategy for miRNA based on bimetallic nanozyme and toehold-mediated DNA replacement procedure.

An electrochemical strategy based on bimetallic nanozyme in collaboration with toehold-mediated DNA replacement effect is proposed for the sensitive determination of miRNA-21. The AuPt nanoparticles (AuPt NPs) are prepared as a catalytic beacon; it shows favorable peroxidase properties with a Michaelis contant (Km) of 0.072 mM for H2O2, which is capable of catalyzing H2O2 to induce an intense redox reaction, and causing a measurable electrochemical signal. To further enhance the strength of the signal response, a novel toehold-mediated DNA replacement strategy is employed. DNA strands with specific sequences are modified on electrodes and AuPt NPs, respectively. In the presence of miRNA-21, a cyclic substitution effect is subsequently activated via a specific toehold sequence and leads to a large accumulation of AuPt NPs on the electrodes. Subsequently, a strong signal depending on the amount of miRNA-21 is obtained after adding a small amount of H2O2. The analytical range of this determination method is from 0.1 pM to 1.0 nM, and the LOD is 84.1 fM. The spike recoveries for serum samples are 95.0 to 102.4% and the RSD values are 3.7 to 5.8%. The results suggests a promising application of the established method in clinical testing and disease diagnosis.

Redox-Responsive Breakup of a Nucleic Acids@CoOOH Nanocomplex Triggering Cascade Recycling Amplification for Sensitive Sensing of Alkaline Phosphatase.

Alkaline phosphatase (ALP), an essential hydrolase with crucial roles in living organisms, has widely been regarded as a biomarker for various human diseases in clinical diagnoses. Herein, taking advantage of cobalt oxyhydroxide (CoOOH) nanoflakes and nonenzymatic cascade recycling amplification (CRA), a highly sensitive and label-free fluorescence biosensing strategy for the determination of ALP activity is introduced. In our design, ALP can promote the dephosphorylation of l-ascorbic acid 2-phosphate (AAP) to reduce ascorbic acid (AA), which is then able to decompose CoOOH in a nucleic acids@CoOOH nanocomplex into Co2+ cofactors. Further, enzyme-free CRA was rapidly initiated by integrating DNAzyme recycling amplification and catalytic hairpin assembly, resulting in the generation of an abundance of G-quadruplex structure-contained DNA duplexes. In the presence of thioflavin T (ThT), analytical target ALP was converted in an amplified and activatable fluorescence signal. The experimental results show that this method can be applied for the quantitative analysis of ALP activity with a low detection limit of 0.027 mU/mL. Moreover, this developed biosensing approach exhibits excellent specificity, and the evaluation of ALP activity in the complex human serum samples was successfully realized, indicating that it can afford a reliable, robust, and cost-effective nanoplatform for an ALP-based clinical diagnosis and for biomedical research.

PGE2 promotes macrophage recruitment and neovascularization in murine wet-type AMD models.

Age-related macular degeneration (AMD), a progressive chronic disease of the central retina, is a leading cause of blindness worldwide. Activated macrophages recruited to the injured eyes greatly contribute to the pathogenesis of choroidal neovascularization (CNV) in exudative AMD (wet AMD). This study describes the effects of cyclooxygenase-2 (COX2)/prostaglandin E2 (PGE2) signalling on the macrophage activation and CNV formation of wet AMD. In a mouse model of laser-induced wet AMD, the mice received an intravitreal injection of celecoxib (a selective COX2 inhibitor). Optical coherence tomography (OCT), fundus fluorescein angiography (FFA), choroidal histology of the CNV lesions, and biochemical markers were assessed. The level of PGE2 expression was high in the laser-induced CNV lesions. Macrophage recruitment and CNV development were significantly less after celecoxib treatment. E-prostanoid1 receptor (EP1R)/protein kinase C (PKC) signalling was involved in M2 macrophage activation and interleukin-10 (IL-10) production of bone marrow-derived macrophages (BMDMs) in vitro. In addition, IL-10 was found to induce the proliferation and migration of human choroidal microvascular endothelial cells (HCECs). Thus, the PGE2/EP1R signalling network serves as a potential therapeutic target for CNV of the wet-type AMD. Video abstract.

A Facile, Label-free and Versatile Fluorescence Sensing Nanoplatform Based on Titanium Carbide Nanosheets for the Detection of Various Targets.

The construction of a universal nanoplatform for sensitive detection of multiple targets of interest is of great importance in different research fields. Herein, by ingeniously integrating the target recognition sequences and G-rich sequences into a single-stranded multifunctional DNA probe and adopting Ti3C2 nanosheets as an efficient fluorescence quencher, a simple, low-cost and easy operation fluorescence sensing nanoplatform was proposed. Without an analytical target, the hydrogen bond and metal chelate interaction between the target recognition region of the DNA probe and Ti3C2 nanosheet induce the selective self-assembly of highly fluorescent thioflavin T (ThT)-intercalated DNA probe onto the surface of Ti3C2 nanosheets, resulting in dramatic decrease of fluorescence emitted by ThT-G-quadruplex. In the presence of a target, the target recognition region will selectively bind with the target and the constrained DNA probe is released from the Ti3C2 nanosheets surface, leading to enhanced fluorescence recovery of ThT-G-quadruplex. As a proof of concept, the sensitive and selective detection of p53 gene, Hg2+, and adenosine with the assistance of Ti3C2 nanosheets-based fluorescence sensing nanoplatform were successfully realized. Moreover, it is also applicable for the evaluation the level of these analytical targets in real samples. By simply switching the recognition sequences of DNA probe, the universal sensing strategy could also be applied for detecting many other types of targets. The simple and universal sensing nanoplatform is expected to promote wide applications in environment monitoring and bioanalysis.

Cu2+-mediated turn-on fluorescence biosensor based on DNA-templated silver nanoclusters for label-free and sensitive detection of adenosine triphosphate.

A Cu2+-mediated turn-on fluorescence biosensor based on the DNA-templated green-emitting silver nanoclusters (DNA@g-AgNCs) was developed for label-free and sensitive detection of adenosine 5'-triphosphate (ATP). Cu2+ was able to quench the bright green fluorescence of DNA@g-AgNCs because of the coordination and photoinduced electron transfer between DNA@g-AgNCs and Cu2+. Therefore, a unique and effective fluorescence biosensor can be constructed with the formation of DNA@g-AgNCs/Cu2+/ATP ternary-competition system. With the introduction of ATP, the DNA@g-AgNCs/Cu2+ fluorescence sensing system will be disrupted and the fluorescence of DNA@g-AgNCs was recovered due to higher affinity of ATP towards Cu2+. On the basis of this feature, the DNA@g-AgNCs/Cu2+ fluorescence sensing system demonstrated quantitative determination of ATP in the range 0.05 - 3 µM and a detection limit of 16 nM. Moreover, the fluorescence sensing system was successfully applied to the quantitative determination of ATP in human urine and serum samples with recoveries ranging from 98.6 to 106.5%, showing great promise to provide  a label-free, cost-efficient, and rapid platform for ATP-related clinical disease diagnosis.

Leaf functional traits differentiation in relation to covering materials of urban tree pits.

BACKGROUND: Understanding the ecological strategies of urban trees to the urban environment is crucial to the selection and management of urban trees. However, it is still unclear whether urban tree pit cover will affect plant functional traits. Here, we study the response of urban trees to different tree pit covers, analyzed the effects of different cover types on soil properties and their trade-off strategies based on leaf functional traits. RESULTS: We found that there were obvious differences in the physical properties of the soil in different tree pit covers. Under the different tree pit cover types, soil bulk density and soil porosity reached the maximum under cement cover and turf cover, respectively. We found that tree pit cover significantly affected the leaf properties of urban trees. Leaf thickness, chlorophyll content index and stomatal density were mainly affected by soil bulk density and non-capillary porosity in a positive direction, and were affected by soil total porosity and capillary porosity in a negative direction. Leaf dry matter content and stomata area were mainly negatively affected by soil bulk density and non-capillary porosity, and positively affected by soil total porosity and capillary porosity. Covering materials of tree pits promoted the functional adjustment of plants and form the best combination of functions. CONCLUSION: Under the influence of tree pit cover, plant have low specific leaf area, stomata density, high leaf thickness, chlorophyll content index, leaf dry matter content, leaf tissue density and stomata area, which belong to "quick investment-return" type in the leaf economics spectrum.

Leaf reflectance and functional traits as environmental indicators of urban dust deposition.

BACKGROUND: How to quickly predict and evaluate urban dust deposition is the key to the control of urban atmospheric environment. Here, we focus on changes of plant reflectance and plant functional traits due to dust deposition, and develop a prediction model of dust deposition based on these traits. RESULTS: The results showed that (1) The average dust deposition per unit area of Ligustrum quihoui leaves was significantly different among urban environments (street (18.1001 g/m2), community (14.5597 g/m2) and park (9.7661 g/m2)). Among different urban environments, leaf reflectance curves tends to be consistent, but there were significant differences in leaf reflectance values (park (0.052-0.585) > community (0.028-0.477) > street (0.025-0.203)). (2) There were five major reflection peaks and five major absorption valleys. (3) The spectral reflectances before and after dust removal were significantly different (clean leaves > dust-stagnant leaves). 695 ~ 1400 nm was the sensitive range of spectral response. (4) Dust deposition has significant influence on slope and position of red edge. Red edge slope was park > community > street. After dust deposition, the red edge position has obviously "blue shift". The moving distance of the red edge position increases with the increase of dust deposition. The forecast model of dust deposition amount established by simple ratio index (y = 2.517x + 0.381, R2 = 0.787, RMSE (root-mean-square error) = 0.187. In the model, y refers to dust retention, x refers to simple ratio index.) has an average accuracy of 99.98%. (5) With the increase of dust deposition, the specific leaf area and chlorophyll content index decreased gradually. The leaf dry matter content, leaf tissue density and leaf thickness increased gradually. CONCLUSION: In the dust-polluted environment, L. quihoui generally presents a combination of characters with lower specific leaf area, chlorophyll content index, and higher leaf dry matter content, leaf tissue density and leaf thickness. Leaf reflectance spectroscopy and functional traits have been proved to be effective in evaluating the changes of urban dust deposition.

Nanozyme based on CoFe2O4 modified with MoS2 for colorimetric determination of cysteine and glutathione.

A nanozyme based on CoFe2O4 modified with MoS2 was constructed for colorimetric determination of cysteine (Cys) and glutathione (GSH). Firstly, ferrite CoFe2O4 is synthesized, and it is then modified by MoS2 to form a flower-like polymer (MoS2@CoFe2O4). In the presence of H2O2, a redox interaction takes place, and the resulting hydroxyl promoted a colorimetric conversion from colorless to blue in the presence of 3,3',5,5'-tetramethylbenzidine (TMB). However, once Cys or GSH is added, they are capable to compete with the interaction of the hydroxyl with TMB, resulting in an inhibition of the colorimetric conversion. The colorimetric distinction is sensitive to the amount of target. The results obtained proved that the catalytic efficiency of MoS2@CoFe2O4 is 4.4-fold and 1.8-fold to that of MoS2 and CoFe2O4. Meanwhile, the Km values to TMB and H2O2 are 0.067 and 0.048 mM, respectively, which are 6.5-fold and 77-fold, respectively smaller than those of natural peroxidase such as HPR. This indicates that the MoS2@CoFe2O4 possesses a favorable interaction affinity. Additionally, the colorimetric distinction caused by the competition between TMB and cysteine or glutathione is obvious. The signal responses to cysteine and glutathione are linear in the range 0.5~15 µM and 0.5~35 µM, and the LODs are 0.10 and 0.21 µM, respectively. In practical assay of Cys in serum, the RSD of the sample tests is 4.6%, and the recoveries for the spiked assays are 95.3% and 96.0% with the RSD of 2.1% and 4.2%, respectively.

A ratiometric fluorescence strategy based on inner filter effect for Cu2+-mediated detection of acetylcholinesterase.

A novel ratiometric fluorescence strategy for detection of acetylcholestinerase (AChE) is proposed based on carbon nitride quantum dots (g-CNQD) and the complex (PA) formed between phenylboronic acid (PBA) and alizarin red S (ARS). PA showed fluorescence at 598 nm and quenched the fluorescence of g-CNQD at 438 nm. Through UV-visible absorption, fluorescence, and fluorescence lifetime measurements, the quenching effect was demonstrated as inner filter effect (IFE). When Cu2+ was added, the coordination of ARS and Cu2+ decreased the fluorescence of PA at 598 nm and recovered that of g-CNQD at 438 nm. In the presence of AChE it catalyzed the hydrolysis of acetylthiocholine (ATCh) to produce thiocholine (TCh) which competed with ARS for binding to Cu2+; thus, the fluorescence at 598 nm increased and that at 438 nm decreased again. Under the mediation of Cu2+, the fluorescence ratio F598/F438 of PA-CNQD probe had good linear relationship with AChE concentration in the range 0.5-15 mU/mL with a detection limit of 0.36 mU/mL. The method was successfully applied to the determination of AChE in human serum and the screening of inhibitors.

DNA cyclic assembling control in an electrochemical strategy with MoS2@AuNPs for determination of kanamycin.

A sensitive electrochemical strategy was established for kanamycin determination. A specific aptamer was modified on the electrode as the probe, followed by a cyclic hybridization chain reaction (HCR) with methylene blue, causing an increasing signal response. In the presence of kanamycin, it can initiatively convolve the aptamer and prevent further DNA assembling, resulting in a signal distinction sensitive to the target amount. However, the signal reproducibility is low. To improve the precision, the HCR procedure was investigated. The results demonstrated that the optimal amount of assembled DNA is 12-fold to that of aptamer. This amount was then controlled in further assays. Admittedly, controlled DNA assembling commonly indicates a limited signal amplification. To further enhance the sensitivity, a nanocomposite based on MoS2 and AuNPs was modified on the electrode. The results of the assay proved that the signal distinction sensitive to target amount increased by 50%. A linearity range is obtained from 0.01 nM to 1.0 µM of kanamycin, and the LOD is 8.4 pM. Subsequently, this strategy was employed to detect kanamycin in chicken liver and milk sample; the recovery results suggest that it possess a satisfactory application prospect in analysis of agricultural products.

Electrochemical sensing platform based on covalent organic framework materials and gold nanoparticles for high sensitivity determination of theophylline and caffeine.

A new covalent organic framework (COF) has been prepared with 1,3,6,8-tetra(4-formyl phenyl) pyrene (TFPPy) and 2,6-diaminopyridine (DP) as building units through a Schiff base reaction by a simple tube oven heating procedure and the structure of the COF has been characterized in detail. The obtained DP-Py COF is employed to fabricate a novel electrochemical sensing platform for sensitive and selective determination of theophylline (TP) and caffeine (CAF) simultaneously through compounding with AuNPs; the peak positions of TP and CAF are 0.95 V and 1.28 V, respectively. The synergistic effect between DP-Py COF and AuNPs effectively enhances the analytical sensitivity for the target analytes. Under the optimized experimental conditions, the electrochemical sensing platform shows a sensitive voltammetric response and wide linear range to both TP and CAF, and the detection limits are 0.19 µM and 0.076 µM (S/N = 3), respectively. This method has been successfully used for the determination of TP and CAF in compound paracetamol capsules and black tea samples. The recovery and relative standard deviations (RSD) of TP are 99.3~101% and 97.6~101% and 1.3~2.0% and 1.3~2.1%, respectively, and the recovery and RSD of CAF are 96.1~102% and 99.4~104% and 2.8~3.9% and 1.7~3.2%, respectively. Compared with traditional detection methods, the constructed sensing platform has better performance and is expected to be widely used also in other real sample analyses.

Effect of simulated warming on leaf functional traits of urban greening plants.

BACKGROUND: Response and adaptation strategies of plants to the environment have always been the core issues in ecological research. So far, relatively little study exists on its functional traits responses to warming, especially in an urban environment. This information is the key to help understand plant responses and trade-off strategy to urban warming. RESULTS: We chose the common greening trees of mature age in Beijing (Fraxinus pennsylvanica, Koelreuteria paniculata, and Sophora japonica) as the research subjects, and used infrared heaters to simulate warming for three gradients of natural temperature (CK), moderate warming (T1) and severe warming (T2). Results showed that:(1) Leaf dry matter content (LDMC), chlorophyll content (CHL), leaf tissue density (LTD), and stomatal density (SD) all increased with temperature warming. Specific leaf area (SLA), stomatal size (SS), and stomatal aperture (SA) decreased with simulated warming. (2) SLA was extremely significantly negatively correlated with CHL, LDMC, LTD and SD (P < 0.01), and was extremely significantly positively correlated with SS (P < 0.01). SA was extremely negatively correlated with SD (P < 0.01), and was extremely significantly positively correlated with SS (P < 0.01). There was a significant positive correlation between LDMC and LTD (P < 0.01). This showed that urban greening trees adapted to the environment by coordinating adjustment among leaf functional traits. (3) Under the T1 treatment, the R2 and slope among the leaf traits were higher than CK, and the significance was also enhanced. The correlation between leaf traits was strengthened in this warming environment. Conversely, it will weaken the correlation between leaf traits under the T2 treatment. CONCLUSION: Our study demonstrated that there was a strong trade-off between leaf functional traits in the urban warming environment. Plants in the warming environment have adopted relatively consistent trade-offs and adaptation strategies. Moderate warming was more conducive to strengthening their trade-off potential. It is further verified that the global leaf economics spectrum also exists in urban ecosystems, which is generally tend to a quick-investment return type with the characteristics of thick leaves, strong photosynthetic capacity, low transpiration efficiency and long life in urban environments.

A ratiometric fluorescence probe based on graphene quantum dots and o-phenylenediamine for highly sensitive detection of acetylcholinesterase activity.

By using graphene quantum dots (GQDs) and o-phenylenediamine (OPD), a ratiometric fluorescence probe was designed for the highly sensitive and selective detection of AChE. GQDs with strong fluorescence were synthesized by the one-step hydrothermal method. The optimal emission wavelength of GQDs was 450 nm at the excitation wavelength of 375 nm. MnO2 nanosheets with a wide absorption band of 300-600 nm were prepared at room temperature. Because of the extensive overlap between the absorption spectrum of MnO2 nanosheets and the excitation and emission spectra of GQDs, the fluorescence of GQDs at 450 nm was efficiently quenched by the inner-filter effect. Meanwhile, due to the peroxidase-like activity of MnO2 nanosheets, OPD was catalytically oxidized to 2,3-diaminophenazine (oxOPD), a yellow fluorescent substance with a new emission peak at 572 nm. When AChE was present, the substrate acetylthiocholine (ATCh) was hydrolyzed to thiocholine (TCh) that is capable of decomposing MnO2 nanosheets. Therefore, the quench of GQDs and the oxidation of OPD by MnO2 nanosheets were suppressed, resulting in the fluorescence recovery of GQDs at 450 nm, while the fluorescence decrease of oxOPD at 572 nm. Utilizing the fluorescence intensity ratio F450/F572 as the signal readout, the ratiometric fluorescence method was established to detect AChE activity. The ratio F450/F572 against the AChE concentration demonstrated two linear relationships in the range 0.1-2.0 and 2.0-4.5 mU mL-1 with a detection limit of 0.09 mU mL-1. The method was applied to the detection of positive human serum samples and the analysis of the inhibitor neostigmine. Due to the advantages of high sensitivity, favorable selectivity, and strong anti-interference, the method possesses an application prospect in clinical diagnosis of AChE and the screening of inhibitors. Graphical abstract Schematic presentation of a ratiometric fluorescence method for the detection of acetylcholinesterase (AChE). The fluorescence of graphene quantum dots (GQDs) is quenched and o-phenylenediamine (OPD) is oxidized to generate fluorescent product 2,3-diaminophenazine (oxOPD) by MnO2 nanosheets. When AChE is present, acetylthiocholine iodide (ATCh) is hydrolyzed to thiocholine (TCh) with reducibility for decomposing MnO2 nanosheets. Due to the decomposition of MnO2 nanosheets, the quenching of GQDs and oxidation of OPD are suppressed. The fluorescence of GQDs at 450 nm is enhanced, while the fluorescence of oxOPD at 572 nm is reduced. The fluorescence intensity ratio F450/F572 is used to establish the ratiometric fluorescence method for AChE activity.

Silicon nanoparticles synthesized using a microwave method and used as a label-free fluorescent probe for detection of VB12.

A simple and rapid detection strategy for vitamin B12 (VB12 ) was established based on label-free silicon quantum dots (SiQDs); the detection mechanism was additionally investigated. SiQDs were synthesized using a one-step microwave method, and their fluorescence was stronger than that synthesized using the hydrothermal method. SiQDs fluorescence was quenched using VB12 due to the inner filter effect (IFE), which was demonstrated using ultraviolet (UV) absorption spectra, fluorescence lifetime, transmission electron microscopy and zeta potential analysis. Subsequently, quercetin (Que) and doxorubicin (Dox) with absorption peaks that overlapped the excitation or emission peaks of SiQDs respectively were used as control groups to investigate the quenching mechanism. Results showed that quenching efficiency was related to the level of overlap between the adsorption peak of the quencher and the excitation or emission peaks of SiQDs. A greater level of overlap caused a higher quenching efficiency. Therefore, the sensitive quenching of VB12 for SiQDs was due to the synergistic effect of the synchronous overlap between the absorption peak of VB12 with the excitation and emission peaks of SiQDs. Fluorescence quenching efficiency increased linearly in the 0.5 to 16.0 µmol·L-1 VB12 concentration range, and the detection limit was 158 nmol·L-1 . In addition, SiQDs were applied to determine VB12 in tablets and human urine samples with satisfactory recoveries ranging from 97.7 to 101.1%.

A novel signal amplification strategy based on the use of copper nanoclusters for ratiometric fluorimetric determination of o-phenylenediamine.

Copper nanoclusters (CuNCs) were synthesized starting from glutathione and copper(II) nitrate. They show blue fluorescence peaking at 432 nm when excited at 334 nm. In the presence of o-phenylenediamine (OPD), the blue fluorescence is decreased, but a yellow fluorescence appears with a peak at 557 nm. UV-visible absorptiometry, fluorometry and fluorescence lifetime measurements were used to show that OPD is oxidized by the small fraction of copper(II) ions present in the CuNCs to form the oxidized form of o-phenylenediamine (oxOPD) which displays weak yellow fluorescence, while the blue fluorescence decreases. The ratio of fluorescences at 557 and 432 nm increases linearly in the 0.15 to 110 µg·L-1 OPD concentration range, and the detection limit is 93 ng·L-1. Compared to the method based on the use of dissolved Cu(II), the employment of CuNCs reduces the detection limit by a factor of 40. The method was applied to the determination of OPD in spiked environmental water and industrial wastewater samples. Recoveries ranged from 96.8 to 100.3%. Graphical abstract Schematic presentation of a ratiometric fluorometric method for detection of o-phenylenediamine (OPD) based on copper nanoclusters (CuNCs). OPD is oxidized by Cu2+ present in CuNCs to form the oxidized form of o-phenylenediamine (oxOPD). FRET occurred between oxOPD and CuNCs, and the F557/F432 value is amplified.

Europium(III) modified silicone nanoparticles for ultrasensitive visual determination of tetracyclines by employing a fluorescence color switch.

Silicon nanoparticles (SiNPs) modified with Eu(III) were synthesized and are shown to be a viable ratiometric fluorescent probe for tetracycline antibiotics. SiNPs/Eu under 405 nm excitation display two emissions, viz. a strong cyan colored fluorescence peaking at 497 nm and a weak pink fluorescence peaking at 622 nm. On addition of tetracyclines (chlortetracycline, tetracycline, doxycycline), the fluorescence at 497 nm is reduced, while the one at 622 nm is increased. Thus, the visible color of fluorescence changes from cyan to pink. This was exploited to design ratiometric fluorometric method for detecting tetracyclines. The method has a limit of detection that is lower by a factor of about 1000 when compared to the use of SiNPs only. A test paper was prepared with the SiNPs/Eu and then applied for the visual semi-quantitative detection of tetracyclines. With the addition of tetracyclines, the test paper exhibited a dosage-sensitive color conversion from cyan to pink with a visually discernible scale as low as 0.4 µM. Graphical abstract Tetracyclines decrease the fluorescence at 497 nm of europium (III) modified silicon nanoparticles (SiNPs/Eu) due to the inner filter effect and increase the one at 622 nm due to an antenna effect. Thus the fluorescence color of SiNPs/Eu changes from cyan to pink. Based on this color switch, a ultrasensitive and visual determination strategy for tetracyclines is proposed.

A multifunctional probe based on the use of labeled aptamer and magnetic nanoparticles for fluorometric determination of adenosine 5'-triphosphate.

A multifunctional fluorescent probe is synthesized for the determination of adenosine 5'-triphosphate (ATP). The 6-carboxyfluorescein-labeled aptamer (FAM-aptamer) was bound to the surface of magnetite nanoparticles coated with polydopamine (Fe3O4@PDA) by π-π stacking interaction to form the multifunctional probe. The probe has three functions including recognition, magnetic separation, and yielding a fluorescent signal. In the presence of ATP, FAM-aptamer on the surface of the probe binds to ATP and returns to the solution. Thus, the fluorescence of the supernatant is enhanced and can be related to the concentration of ATP. Fluorescence intensities were measured at excitation/emission wavelengths of 494/526 nm. Response is linear in the 0.1-100 µM ATP concentration range, and the detection limit is 89 nM. The probe was applied to the quantitation of ATP in spiked human urine and serum samples, with recoveries ranging between 94.8 and 102%. Graphical abstract A multifunctional fluorescent probe based on the use of FAM-aptamer and Fe3O4@PDA is described for the determination of ATP in spiked human urine and serum samples. FAM-aptamer: 6-carboxyfluorescein-labeled aptamer; Fe3O4@PDA: magnetite nanoparticles coated with polydopamine. ATP: adenosine 5'-triphosphate.

Two deletion variants of Middle East respiratory syndrome coronavirus found in a patient with characteristic symptoms.

Significant sequence variation of Middle East respiratory syndrome coronavirus (MERS CoV) has never been detected since it was first reported in 2012. A MERS patient came from Korea to China in late May 2015. The patient was 44 years old and had symptoms including high fever, dry cough with a little phlegm, and shortness of breath, which are roughly consistent with those associated with MERS, and had had close contact with individuals with confirmed cases of MERS.After one month of therapy with antiviral, anti-infection, and immune-enhancing agents, the patient recovered in the hospital and was discharged. A nasopharyngeal swab sample was collected for direct sequencing, which revealed two deletion variants of MERS CoV. Deletions of 414 and 419 nt occurred between ORF5 and the E protein, resulting in a partial protein fusion or truncation of ORF5 and the E protein. Functional analysis by bioinformatics and comparison to previous studies implied that the two variants might be defective in their ability to package MERS CoV. However, the mechanism of how these deletions occurred and what effects they have need to be further investigated.

Tunable and Nontoxic Fluorescent Probes Based on Carbon Dots for Imaging of Indole Propionic Acid Receptor in Plant Tissues in Situ.

Indole propionic acid (IPA) is one of the important plant growth hormones for promoting rooting and fruiting. Labeling IPA receptor in plant tissues is able to further track the signal transduction processes of IPA and uncover the function mechanism of IPA on crop productions. In this paper, a tunable and nontoxic fluorescent probe for IPA receptors was designed and synthetized base on carbon dots (C dots). Firstly carboxyl-modified carbon dots were prepared by high temperature cracking of citric acid. The fluorescence emission wavelengths of C dots varied with the excitation wavelengths change. Then IPA-modified carbon dots (IPA-C dots) were prepared by coupling the amino of tryptophan with the carboxyl of as-prepared carbon dots. Compared with C dots, the fluorescence intensity of IPA-C dots was double and the fluorescence stability was satisfactory under various conditions. This probe retained the biological activity of IPA and acted as target recognition of IPA receptors in plant tissues. The probe could avoid green fluorescence background of plants. The imaging results showed that the IPA receptors mainly existed on the membrane of stele. The toxicity test indicated the probe was less toxic than traditional inorganic semiconductor quantum dots.