An activatable fluorescent-photoacoustic dual-modal probe for highly sensitive imaging of nitroxyl in vivo.

Nitroxyl (HNO) plays a vital role in various biological functions and pharmacological activities, so the development of an excellent near-infrared fluorescent (NIRF) and photoacoustic (PA) dual-modality probe is crucial for understanding HNO-related physiological and pathological progression. Herein, we proposed and synthesized a novel NIRF/PA dual probe (QL-HNO) by substituting an indole with quinolinium in hemicyanine for the sensitive detection of exogenous and endogenous HNO in vivo. The designed probe showed the highest sensitivity in NIRF mode and a desirable PA signal-to-noise ratio for HNO detection in vitro and was further applied for NIRF/PA dual-modal imaging of HNO with high contrast in living cells and tumor-bearing animals. Based on the excellent performance of QL-HNO, we believe that this study provides a promising molecular tool for further understanding of HNO-related physiological and pathological progression.

Rational design of a negative photochromic spiropyran-containing fluorescent polymeric nanoprobe for sulfur dioxide derivative ratiometric detection and cell imaging.

It is highly desirable to develop high-performance ratiometric fluorescent probes for SO2 derivative detection and realize their application in biological imaging. In this study, we report the rational design of a novel negative photochromic spiropyran derivative, spiro[azahomoadamantane-pyran] (MAHD-SP), with notable orange fluorescence in its stable ring-opened state without UV regulation. The unsaturated double bond of MAHD-SP underwent the Michael addition reaction of the SO2 derivative, making the fluorescence quenching of MAHD-SP obvious. Then, MAHD-SP, a fluorescent conjugated polymer PFO and a polymeric surfactant PEO113-b-PS49 were used to construct a ratiometric fluorescent polymeric nanoprobe (RFPN) via a coprecipitation method. The probe exhibited high sensitivity and selectivity for the ratiometric detection of SO2 derivatives in pure aqueous solutions. Moreover, the good biocompatibility of RFPN can be used to visualize exogenous and endogenous SO2 derivative generation in living cells.

Recombinant Fusion Streptavidin as a Scaffold for DNA Nanotetrads for Nucleic Acid Delivery and Telomerase Activity Imaging in Living Cells.

Efficient platforms for intracellular delivery of nucleic acids are essential for biomedical imaging and gene regulation. We develop a recombinant fusion streptavidin as a novel protein scaffold for DNA nanotetrads for highly efficient nucleic acid delivery and telomerase activity imaging in living cells via cross-linking hybridization chain reaction (cHCR). The recombinant streptavidin protein is designed to fuse with multiple SV40 NLS (nuclear localization signal) and NES (nuclear export signal) domains and prepared through Escherichia coli expression. The recombinant NLS-SA protein allows facile assembly with four biotinylated DNA probes via high-affinity noncovalent interactions, forming a well-defined DNA tetrad nanostructure. The DNA nanotetrads are demonstrated to confer efficient cytosolic delivery of nucleic acid via a caveolar mediated endocytosis pathway, allowing efficient escape from lysosomal degradation. Moreover, the nanotetrads enable efficient cHCR assembly in response to telomerase in vitro and in cellulo, affording ultrasensitive detection and spatially resolved imaging for telomerase with a detection limit as low as 90 HeLa cells/mL. The fluorescence brightness obtained in live cell imaging is found to be dynamically correlated to telomerase activity and the inhibitor concentrations. Therefore, the proposed strategy may provide a highly efficient platform for nucleic acid delivery and imaging of biomarkers in living cells.

Selective ratiometric fluorescence detection of hypochlorite by using aggregation-induced emission dots.

The development of simple and effective tools for selective ratiometric detection of hypochlorite (ClO-) is one of the most important goals for elucidating the biofunction of ClO- in associated diseases. However, most developmental probes suffer from the notorious aggregation-caused quenching (ACQ) effect that greatly limits their applications. Herein, we report on novel aggregation-induced emission dots (AIED) for ratiometric detection of ClO- via a co-precipitation strategy. The AIED nanoprobe displayed a ratiometric signal output, which was more promising to minimize the bad environmental factors and simultaneously avoided the ACQ effect. Notably, amphiphilic block copolymer endowed the nanoprobe with stable water dispersibility and easy modification. The as-prepared AIED probe exhibited high sensitivity (~ 89 nM), high selectivity, outstanding photostability, and prominent long-term fluorescence stability. Furthermore, the as-prepared AIED was applied for the visualized fluorescence detection of ClO- and further utilized to detect ClO- in real samples. We expect the nanoprobe to be an outstanding tool to understand ClO--associated diseases. Graphical abstract Illustration of the probe for the detection of ClO-.

Tumor-Targeted Graphitic Carbon Nitride Nanoassembly for Activatable Two-Photon Fluorescence Imaging.

Unique physicochemical characteristics of graphitic carbon nitride (g-CN) nanosheets suit them to be a useful tool for two-photon fluorescence bioimaging. Current g-CN nanosheets based imaging probes typically use the "always-on" design strategies, which may suffer from increased fluorescence background and limited contrast. To advance corresponding applications, g-CN nanosheets based activatable two-photon fluorescence probes remain to be explored. For the first time, we developed an activatable two-photon fluorescence probe, constructed from a nanoassembly of g-CN nanosheets and hyaluronic acid (HA)-gold nanoparticles (HA-AuNPs), for detection and imaging of hyaluronidase (HAase) in cancer cells. The deliberately introduced HA in our design not only functions as the buffering layer for stabilizing AuNPs and inducing corresponding self-assembly on g-CN nanosheets but also as a pilot for targeting HA receptors overexpressed on cancer cell surfaces. Our results show that the developed nanoassembly enables specific detection and activatable imaging of HAase in cancer cells and deep tissues, with superb signal-to-background ratio and high sensitivity. This nanoassembly can afford a promising platform for highly specific and sensitive imaging of HAase and for related cancer diagnosis.

Potential biomarkers for monitoring the toxicity of long-term exposure to atrazine in rat by metabonomic analysis.

1. Herbicide atrazine (ATR) poses harmful effects on human health. The purpose of this study is to study potential biomarkers used for monitoring the toxic effects after chronic exposure to ATR by studying urine metabolites. 2. Rats were assigned into clinical chemistry and metabonomics arms, and each arm was divided into low-dose, high-dose and control groups. ATR was administered to rats along with their feed. At the end of 16, 20 and 24 weeks, clinical parameters and histopathologic changes was assessed to monitor the toxic effects. Twenty-four hour urine samples was analyzed by UPLC-MS, to find the significant alterations in metabolic profiling. 3. The body weight of rats in ATR group was lower than that of control starting from 12th week; abnormal levels of serum biochemistry and histopathologic alterations of organs were found initially from 16th and 20th week, respectively. Five exogenous and five endogenous metabolites were found which showed significant differences between ATR groups and control group at above-mentioned time points. 4. These metabolites may be used as potential indicators to monitor ATR toxicity, and also may provide some clues for understanding the mechanism of toxicity of ATR. The exact relationship between endogenous metabolites and ATR toxicity needs further investigation.

Plasmon Coupling Enhanced Raman Scattering Nanobeacon for Single-Step, Ultrasensitive Detection of Cholera Toxin.

We report the development of a novel plasmon coupling enhanced Raman scattering (PCERS) method, PCERS nanobeacon, for ultrasensitive, single-step, homogeneous detection of cholera toxin (CT). This method relies on our design of the plasmonic nanoparticles, which have a bilayer phospholipid coating with embedded Raman indicators and CT-binding ligands of monosialoganglioside (GM1). This design allows a facile synthesis of the plasmonic nanoparticle via two-step self-assembly without any specific modification or chemical immobilization. The realization of tethering GM1 on the surface imparts the plasmonic nanoparticles with high affinity, excellent specificity, and multivalence for interaction with CT. The unique lipid-based bilayer coated structure also affords excellent biocompatibility and stability for the plasmonic nanoparticles. The plasmonic nanoparticles are able to show substantial enhancement of the surface-enhanced Raman scattering (SERS) signals in a single-step interaction with CT, because of their assembly into aggregates in response to the CT-sandwiched interactions. The results reveal that the developed nanobeacon provides a simple but ultrasensitive sensor for rapid detection of CT with a large signal-to-background ratio and excellent reproducibility in a wide dynamic range, implying its potential for point-of-care applications in preventive and diagnostic monitoring of cholera.

Catalytic Hairpin Assembly-Based Self-Ratiometric Gel Electrophoresis Detection Platform for Reliable Nucleic Acid Analysis.

The development of gel electrophoresis-based biodetection assays for point-of-care analysis are highly demanding. In this work, we proposed a ratiometric gel electrophoresis-based biosensing platform by employing catalytic hairpin assembly (CHA) process functions as both the signal output and the signal amplification module. Two types of nucleic acids, DNA and miRNA, are chosen for demonstration. The proposed strategy indeed provides a new paradigm for the design of a portable detection platform and may hold great potential for sensitive diagnoses.

Supramolecular Polymers with Photoswitchable Multistate Fluorescence for Anti-Counterfeiting and Encryption.

Photoswitchable fluorescent materials are desirable for many applications because their emission signals can be easily modulated on demand. In this study, novel photoswitchable multistate fluorescent supramolecular polymers (PMFSPs) were prepared via host-guest interactions under a facile ultrasonication strategy. In the system, photochromic fluorescent diarylethylene monomer (SDTE, donor) and adamantane-containing monomer (BAC) were covalently combined into the backbone of the guest polymer (P1) via radical copolymerization. Meanwhile, the host moiety (CDSP, acceptor) was synthesized by covalent incorporation of photochromic spiropyran dye (SPCOOH) with ß-cyclodextrin. By adjusting the stimulation wavelength and utilizing photoinduced fluorescence resonance energy transfer (FRET), the supramolecular polymers can undergo reversible tristate fluorescence switching among none, red, and green. In addition, due to the high contrast, rapid photoresponsiveness and prominent photoreversibility of the prepared PMFSPs, we demonstrated that they have great potential in advanced anti-counterfeiting and multilevel information encryption.

Enzymatic control of plasmonic coupling and surface enhanced Raman scattering transduction for sensitive detection of DNA demethylation.

We have developed a novel concept for enzymatic control of plasmonic coupling as a surface enhanced Raman scattering (SERS) nanosensor for DNA demethylation. This nanosensor is constructed by decorating gold nanoparticles (AuNPs) with Raman reporters and hemimethylated DNA probes. Demethylation of DNA probes initiates a degradation reaction of the probes by methylation-sensitive endonuclease Bsh 1236I and single-strand selective exonuclease I. This destabilizes AuNPs and mediates the aggregation of AuNPs, generating a strong plasmonic coupling SERS signal in response to DNA demethylation. This nanosensor has the advantages in its high signal-to-noise ratio, superb specificity, and rapid, convenient, and reproducible detection with homogeneous, single-step operation. Thus, it provides a useful platform for detecting DNA demethylation and related molecular diagnostics and drug screening. This work is the first time that enzymatic degradation of DNA substrate probes has been utilized to induce aggregation of AuNPs such that reproducible, sensitive SERS signals can be achieved from biological recognition events. This enzymatic control mechanism for plasmonic coupling may create a new paradigm for the development of SERS nanosensors.

pH-Responsive DNA nanoassembly for detection and combined therapy of tumor.

We have developed a novel cancer theragnostic nanoassembly with high biocompatibility, stability and low toxicity which are activated rapidly by tumor microenvironment to realize selective fluorescence imaging, chemotherapy as well as chemoenzymatic therapy. The nanoprobes are synthesized by hybridization of fluorophore labeled hairpin DNAs containing a 5-aza-dC at hemimethylated CpG sites and pH-sensitive DNA sequence covalently conjugated with PEGylated GO. The aptamer, which is also covalently conjugated on PEGylated GO, enables to target the tumor site and the weak acid environment of tumor triggers the release of drug loaded by nanoprobes including functionalized DNA and DOXs, effectively activating fluorescence signals and selectively killing the tumor cells. The results revealed that the nanoprobe enables sensitive detection of pH changes within subcellular environment, selectively imaging and great synergy of multicombination therapeutic including chemotherapy and chemoenzymatic therapy, implying that developed pH activatable probe has considerable potential for diagnosis and efficient therapy of cancer.

Cross-Linking Induced Emission of Polymer Micelles for High-Contrast Visualization Level 3 Details of Latent Fingerprints.

Rationally developing an intelligent tool for high-contrast fluorescence imaging of latent fingerprints (LFPs) is gaining much concern in many applications such as medical diagnostics and forensic investigations. Herein, the off-on fluorescent polymer micelles (PMs) have been rationally designed and synthesized for high-contrast fluorescence imaging of LFPs through the cross-linking reaction of hydrazine (N2H4) and aldehyde group of polymer. Excitingly, the cross-linking (N2H4) induced emission of PMs has the property of aggregation-induced emission (AIE) and excited state intramolecular proton transfer (ESIPT), which could effectively address the notorious aggregation-caused quenching (ACQ) effects of conventional organic dyes. In addition, the cross-linking strategy can not only improve structural stability of PMs but also enhance its fluorescence brightness. The experiment results demonstrated that PMs showed high water dispersibility (100% aqueous solution), high selectivity, large Stokes shift (∼150 nm), good photostability, and excellent long-term stability. Because of the hydrophobic interaction between the PMs and fingerprint components, the PMs preferentially adhered onto the ridges of fingerprint, and then cross-linking (N2H4) induced emission properties endowed the PMs for high-contrast imaging of LFPs in different substrates, especially the levels 1-3 details of LFPs. We expect that this strategy will provide vital support for LFPs technology.

Rational design of a HA-AuNPs@AIED nanoassembly for activatable fluorescence detection of HAase and imaging in tumor cells.

Aggregation induced emission (AIE) dots have gained broad attention in fluorescence bioimaging and biosensors in virtue of their distinctive optical properties of splendid biocompatibility, high brightness and good photostability. However, the application of AIE dots in sensing and imaging of enzymes in cells remains at an early stage and needs to be further explored. In this report, we proposed a novel AIE-dot-based nanoprobe for hyaluronidase (HAase) detection using a simple electrostatic self-assembly of AIE dots with gold nanoparticles functionalized using hyaluronic acid (HA-AuNPs), named HA-AuNPs@AIEDs. The fluorescence of AIE dots can be obviously quenched by HA-AuNPs via fluorescence resonance energy transfer (FRET). HAase could degrade HA into small pieces and thus induce disassembly of AuNPs and AIEDs, accompanied by fluorescence recovery of AIEDs. The as-prepared nanoprobe exhibited high sensitivity, excellent selectivity, wide response range and desirable anti-interference for quantitative sensing of HAase in vitro. The detection limit was down to 0.0072 U mL-1. Moreover, the nanoprobe displayed good biocompatibility and excellent photostability, and thus offered a practicable "turn-on" strategy for specific, high-contrast fluorescence imaging of HAase in live tumor cells. The AIE-based nanoprobe may provide a novel universal platform for recognition and imaging of HAase in tumors, and may be beneficial for related biological research.

Self-Assembly of a Dual-Targeting and Self-Calibrating Ratiometric Polymer Nanoprobe for Accurate Hypochlorous Acid Imaging.

Exploiting an intelligent fluorescent probe, which can precisely target to the lysosome of hepatoma cells and enable accurate molecular imaging, is a key challenge in hepatoma diagnoses. Herein, a single-dye-based polymer nanoprobe (named SPN) with dual-targeting and self-calibrating ratiometric characteristics is rationally fabricated via a simple self-assembly strategy for accurate hypochlorous acid (HClO) imaging in the lysosome of HepG2 cells. Of note, the covalent incorporation of self-calibrating ratiometric fluorophore (pyrene derivatives) into the core of polymer nanoparticles can not only validly avoid the leakage of fluorophores but also greatly enhance their brightness. Besides, this polymer nanoprobe (SPN) displays high water dispersibility, ultrafast response (<1s), favorable selectivity, outstanding long-term stability (>90 days), and good biocompatibility. Furthermore, thanks to the hepatocyte-targeting moiety (galactose) and the interplay of surface charge and size of nanoparticles, the SPN is able to enter into asialoglycoprotein receptor-positive HepG2 cells and further locate at lysosomes, successfully enabling accurate HClO detection in lysosomes of HepG2 cells. This study demonstrates that the versatile SPN can provide more precise dual-targeting and accurate molecular imaging.

[Effects of spraying salicylic acid and potassium dihydrogen phosphate on physiological cha-racteristics and grain yield of single-season rice under high temperature condition]. / é«˜æ¸©ä¸‹å–·æ–½æ°´æ¨é ¸å’Œç£·é ¸äºŒæ°¢é’¾å¯¹ä¸­ç¨»ç”Ÿç†ç‰¹å¾å’Œäº§é‡çš„å½±å“.

To explore new practical means of alleviating the negative effect of heat stress on rice plants during the heading-flowering stage, a field experiment was conducted in Ji'an, Yugan, and Nanchang counties of Jiangxi Province from 2017 to 2018 with three indica hybrid rice varieties. Under ambient high temperature condition during the heading-flowering period, we sprayed five concentrations of salicylic acid (SA) (SA1-SA5: 100, 500, 1000, 1500, 2000 µmol·L-1) and five concentrations of KH2PO4 (K1-K5: 7.35, 14.70, 22.05, 29.40, 36.75 mmol·L-1) on the leave of rice, with deionized water as the control (CK), to mesure the physiological characteristics and grain yield. The results showed that compared to CK,plants treated with SA and KH2PO4 had higher chlorophyll content, soluble sugar content, soluble protein content, proline content, supero-xide dismutase activity, and peroxidase activity, but a lower malonaldehyde content, among which SA2 and K3 treatments performed the best. The treatments of SA2, SA3, K3, and K4 increased the number of grains per panicle, seed-setting rate, and grain yield, with the effects of SA2 and K3 treatments being significant. Compared to CK, the SA2 treatments enhanced the number of grains per panicle, seed-setting rate, and grain yield by 7.0%, 4.0%, and 11.9%, respectively; the K3 treatments enhanced the number of grains per panicle, seed-setting rate, and grain yield by 3.9%, 4.7%, and 6.6%, respectively. The optimal measure was spraying 500 µmol·L-1 SA or 22.05 mmol·L-1 KH2PO4, which could significantly increase grain yield of single-season rice under high temperature condition during the heading-flowering period.

Conjugated polymer nanoparticles-based fluorescent biosensor for ultrasensitive detection of hydroquinone.

This work describes a simple and sensitive fluorescent method for detection of hydroquinone utilizing conjugated polymer nanoparticles (CPNs). The CPNs serve both as a catalyst to accelerate the conversion of hydroquinone to benzoquinone and a fluorescent probe. In the presence of hydroquinone, the fluorescence of CPNs can be effectively quenched by benzoquinone. The detection limit of hydroquinone was down to 5 nM and excellent selectivity toward possible interferences was obtained. This method was successfully applied for hydroquinone detection in lake water and satisfactory results were achieved.

Amplified Split Aptamer Sensor Delivered Using Block Copolymer Nanoparticles for Small Molecule Imaging in Living Cells.

We develop a novel amplified split aptamer sensor for highly sensitive detection and imaging of small molecules in living cells by using cationic block copolymer nanoparticles (BCNs) with entrapped fluorescent conjugated polymer as a delivery agent. The design of a split aptamer as the initiator of hybridization chain reaction (HCR) affords the possibility of enhancing the signal-to-background ratio and thus allows high-contrast imaging for small molecules with relatively weak interactions with their aptamers. The novel design of using fluorescent cationic BCNs as the nanocarrier enables efficient and self-tracking transfection of DNA probes. Results reveal that BCNs exhibit high fluorescence brightness allowing direct tracking of the delivery location. The developed amplified split aptamer sensor is shown to have high sensitivity and selectivity for in vitro quantitative detection of adenosine triphosphate (ATP) with a detection limit of 30 nM. Live cell studies show that the sensor provides a "signal on" approach for specific, high-contrast imaging of ATP. The DNA sensor based HCR system may provide a new generally applicable platform for detection and imaging of low-abundance biomarkers.

Chinese Society of Allergy Guidelines for Diagnosis and Treatment of Allergic Rhinitis.

Allergic rhinitis (AR) is a global health problem that causes major illnesses and disabilities worldwide. Epidemiologic studies have demonstrated that the prevalence of AR has increased progressively over the last few decades in more developed countries and currently affects up to 40% of the population worldwide. Likewise, a rising trend of AR has also been observed over the last 2-3 decades in developing countries including China, with the prevalence of AR varying widely in these countries. A survey of self-reported AR over a 6-year period in the general Chinese adult population reported that the standardized prevalence of adult AR increased from 11.1% in 2005 to 17.6% in 2011. An increasing number of Journal Articles and imporclinical trials on the epidemiology, pathophysiologic mechanisms, diagnosis, management and comorbidities of AR in Chinese subjects have been published in international peer-reviewed journals over the past 2 decades, and substantially added to our understanding of this disease as a global problem. Although guidelines for the diagnosis and treatment of AR in Chinese subjects have also been published, they have not been translated into English and therefore not generally accessible for reference to non-Chinese speaking international medical communities. Moreover, methods for the diagnosis and treatment of AR in China have not been standardized entirely and some patients are still treated according to regional preferences. Thus, the present guidelines have been developed by the Chinese Society of Allergy to be accessible to both national and international medical communities involved in the management of AR patients. These guidelines have been prepared in line with existing international guidelines to provide evidence-based recommendations for the diagnosis and management of AR in China.

Oral Exposure to Atrazine Induces Oxidative Stress and Calcium Homeostasis Disruption in Spleen of Mice.

The widely used herbicide atrazine (ATR) can cause many adverse effects including immunotoxicity, but the underlying mechanisms are not fully understood. The current study investigated the role of oxidative stress and calcium homeostasis in ATR-induced immunotoxicity in mice. ATR at doses of 0, 100, 200, or 400 mg/kg body weight was administered to Balb/c mice daily for 21 days by oral gavage. The studies performed 24 hr after the final exposure showed that ATR could induce the generation of reactive oxygen species in the spleen of the mice, increase the level of advanced oxidation protein product (AOPP) in the host serum, and cause the depletion of reduced glutathione in the serum, each in a dose-related manner. In addition, DNA damage was observed in isolated splenocytes as evidenced by increase in DNA comet tail formation. ATR exposure also caused increases in intracellular Ca2+ within splenocytes. Moreover, ATR treatment led to increased expression of genes for some antioxidant enzymes, such as HO-1 and Gpx1, as well as increased expression of NF-κB and Ref-1 proteins in the spleen. In conclusion, it appears that oxidative stress and disruptions in calcium homeostasis might play an important role in the induction of immunotoxicity in mice by ATR.

Enzymatic activatable self-assembled peptide nanowire for targeted therapy and fluorescence imaging of tumors.

We developed novel activatable probe using self-assembled peptide nanowires with low affinity and toxicity to tumor cells in the absence of matrix metalloproteinase that showed activated high affinity and toxicity and provided a highly selective and efficient platform for targeted therapy and tumor imaging.