General Separation of Carbon Dots by Polyamide Chromatography.

Carbon dot (C-dot) separation/purification is not only a fundamental chemical issue but also an essential precondition for revealing C-dots' true nature. To date, adequate separation of C-dots has remained an open question due to the lack of an appropriate fine separation system. Herein, we discover and reveal that polyamide chromatography can provide versatile and powerful performances for C-dot separation. By a joint study of experiments and all-atom molecular dynamics simulations, we demonstrate that multiple interaction forces, including electrostatic repulsion/attraction, hydrogen bond, and van der Waals effects, exist simultaneously among the stationary phase, mobile phase, and the separated C-dots. Furthermore, the magnitude of these forces is dependent on the surface chemistry of the separated C-dots and the nature of the used mobile phases, providing a theoretical basis and experimental operability for C-dot separation. So, the proposed system possesses the capacity for adequately separating hydrophilic, amphiphilic, and lipophilic C-dots. The polyamide chromatography, due to its versatile and powerful separation performances, not only provides more thorough separation effects but also helps to correct our false perceptions from inadequate purified C-dots.

Thiols Modulated Gold Nanorods Self-Assembly: Indirect Hydrophobic Effects Instead of Direct Electrostatic/Hydrogen Bonds Attraction.

For nanocrystals (NCs) self-assembly, understanding the chemical and supramolecular interactions among building blocks is significant for both fundamental scientific interests and rational nanosuperstructure construction. However, it has remained an extreme challenge for many self-assembly systems due to the lack of appropriately quantitative approaches for the corresponding exploration. Herein, by combination of the proposed colorimetric method for cationic surfactant quantitation and all-atom simulations, we manage to present a clear chemical picture for the thiol molecules modulated self-assembly of gold nanorods (GNRs), one of the earliest and most convenient methods for the fabrication of freestanding GNR self-assemblies. It is revealed that the self-assembly of GNRs is driven by the hydrophobic effects of the alkyl chains of the modified cationic surfactants, as their bilayer structure is destroyed by the added thiol molecules. In other words, the actual roles of the thiol molecules for causing GNRs assembly are indirectly inductive effects instead of the previously believed direct electrostatic attraction and/or hydrogen-bond linking effects of the binding thiol molecules. Furthermore, the GNRs exhibit diameter-dependent assembly behaviors: thicker GNRs tend to adopt the end-to-end assembly mode, while thin ones prefer the side-by-side assembly mode, further demonstrating that hydrophobic effects among the build blocks are the driving force for the GNRs assembly.

Liver Injury Traceability: Spatiotemporally Monitoring Oxidative Stress Processes by Unit-Emitting Carbon Dots.

Exploring the etiology of liver injury is critical to fundamental science and precise treatment, which has not yet been achieved by molecule imaging techniques. Herein, we manage to conquer this challenge by spatiotemporally monitoring oxidative stress processes using the proposed unit-emitting carbon dots (UE-C-dots) as fluorescent probes. We discover and reveal that the UE-C-dots can specifically determine hypochlorous acid (HClO) molecules, one of the important reactive oxygen/nitrogen species (ROS/RNS) in liver injury, by an excited state oxidation mechanism. Other ROS/RNS do not interfere with the assay even if their concentrations are 1000 times higher than that of HClO due to the lowest unoccupied molecular orbital level mismatch. Real-time tomographic imaging demonstrates that different stimuli cause distinctly different HClO bursts in both temporal and spatial dimensionalities. Therefore, the measurement and analysis of temporal information substantially extend our understanding on the relationships of hepatic oxidative stress and corresponding physiological/pathological behaviors.

Fabrication of ternary AgBr/BiPO4/g-C3N4 heterostructure with dual Z-scheme and its visible light photocatalytic activity for Reactive Blue 19.

A plasmonic photocatalyst of AgBr/BiPO4/g-C3N4 was prepared. X-ray powder diffraction, Scanning electron microscope, Transmission electron microscopy, Fourier infrared spectroscopy, Ultraviolet Visible diffuse reflectance spectroscopy and photoluminescence emission spectra have been employed to determine the structure, morphology and optical property of the as-prepared AgBr/BiPO4/g-C3N4 composite and analysis the reasons for improving photocatalytic efficiency. The optimal doping ratio of AgBr was 10 wt% by degrading 20 mg/L of Reactive Blue 19 (RB19) under visible light (λ > 420 nm), and 10 wt%AgBr/BiPO4/g-C3N4 degraded 20 mg/L of RB19 to 2.59% at 40 min, which is ascribed to synergistic effects at the interface of AgBr, BiPO4 and g-C3N4. The effect of catalyst dosage, initial concentration and initial pH of RB19 solution on photocatalytic efficiency was investigated. Four cycles of experiments were conducted. Finally, through the trapping experiment, we found that the main active factor for degrading RB19 in the photocatalytic process is O2-. The possible photocatalytic mechanism of AgBr/BiPO4/g-C3N4 was discussed in connection with the synergistic effect of Ag and active substances at the AgBr/BiPO4/g-C3N4 interface.

Characterization of Novel Bacteriophage AhyVDH1 and Its Lytic Activity Against Aeromonas hydrophila.

Phage therapy is an alternative approach to overcome the problem of multidrug-resistant bacteria. Here, a novel bacteriophage AhyVDH1, which infects Aeromonas hydrophila 4572, was isolated and its morphology, one-step growth curve, lytic activity, stability under various conditions, and genome were investigated. Transmission electron microscopy revealed that AhyVDH1 has an icosahedral head 49 nm in diameter and a contractile tail 127 nm in length, suggesting that it belongs to the family Myoviridae. AhyVDH1 showed strong adsorption to the surface of A. hydrophila 4572 (90% in 10 min). The latent period of AhyVDH1 was shown to be 50 min, and the burst size was 274 plaque-forming unit/infected cell. AhyVDH1 was stable at 30 °C for 1 h and lost infectivity after20 min of heating at 60 °C. Infectivity remained unaffected at pH 6-7 for 1 h, while the bacteriophage was inactivated at pH < 4 or > 11. AhyVDH1 has a 39,175-bp genome, with a 58% G + C content and 59 open reading frames. BLAST analysis indicated that the genome sequence of phage AhyVDH1 was related to that of Aeromonas phage Ahp2. Both time and MOI-dependent in vitro A. hydrophila growth inhibition were observed with AhyVDH1.Re-growth of the host bacteria appeared about 12 h after treatment, suggesting its potential therapeutic value in treating A. hydrophila infections, but phage cocktails should be developed.

Mycorrhiza and Iron Tailings Synergistically Enhance Maize Resistance to Arsenic on Medium Arsenic-Polluted Soils Through Increasing Phosphorus and Iron Uptake.

Agricultural arsenic (As, CAS. No. 7440-38-2) over the issue of pollution has been related to people's livelihood, security and moderate use of As contaminated soil is an important aspect of contaminated soil remediation. In this potted plant experiment, synergistic effects of arbuscular mycorrhizal fungi (AMF) Funneliformis mosseae and iron (Fe, CAS. No. 7439-89-6) oxides on plant growth and phosphorus (P, CAS. No. 7723-14-0), As and Fe uptake by maize (Zea mays L.) were studied on simulating medium As-polluted soils in greenhouse. Different amounts (0, 5, 10, 20, 40 g kg- 1) of iron tailings (IT) were added. The results showed that IT20 and IT40 addition significantly increased mycorrhizal infection rate, plant biomass, root length and P, Fe uptake under FM treatment; IT40 addition decreased As concentration in roots. In addition, FM inoculation increased biomass, root length and P uptake by shoots, but decreased Fe and As concentration in shoots. Therefore, the combined FM inoculation and IT40 addition promoted maize growth and decreased As concentration in shoots by decreasing As absorption efficiency, increasing P and Fe uptake and P/As ratio.

Carbon Dot Nanozymes: How to Be Close to Natural Enzymes.

The design, catalytic process, and property study of nanozymes are of importance for both fundamental research and application demand. Here, the peroxidase-mimicking properties of a series of carbon dots (C-dots) was systematically investigated and they were found to be probably closer to their natural counterparts, as compared to the known corresponding nanozymes. Firstly, four kinds of metal-free and surface-modulated C-dots were bottom-up fabricated using glucose, α-cyclodextrin (CD), ß-CD, and γ-CD as precursors, respectively, and their formation processes, structures, as well as surface chemistry were investigated. Secondly, in the peroxidase-mimicking catalytic system, no hydroxyl radicals were produced, which indicates a different and special catalytic mode. By employing a joint experimental-theoretical study, a probable catalytic mechanism is proposed. Thirdly, the present C-dots maintained well their catalytic activity even in complicated serum matrices because their catalytic performances are completely irrelevant of any cation-related binding sites. Finally, the catalytic performances of the as-prepared C-dots were modulated by either pre-engineering NP surface structures or subsequently introducing photo-regulated host-guest reactions.

Optical, electrochemical and catalytic methods for in-vitro diagnosis using carbonaceous nanoparticles: a review.

This review (with 261 refs.) summarizes the progress that has been made in the field of in-vitro diagnosis using carbonaceous nanoparticles (CNPs). Signal readout is mostly based on fluorometry, electrochemistry and colorimetry. Following an introduction, the next two sections cover methods for the fabrication and separation of CNPs. This is followed by sections on (a) fluorometric methods, (b) electrochemical methods, and (c) colorimetric methods for detecting various analytes. Several subsections discuss detection schemes for analytes such as metal ions, pH value, reactive oxygen species, small biogenic molecules (for example glucose, ascorbic acid, amino acids, dopamine), and biomacromolecules (such as enzymes, cancer markers, DNA). A further section discusses methods based on the peroxidase-like activity of CNPs, and how they can be employed for the determination of species such as glucose, cholesterol, glutathione, and uric acid via H2O2-based chromogenic methods. Finally, the challenges and future perspectives in this research area are discussed. Graphical abstract A review is presented on the progress that has been made in recent years in sensing platforms for in-vitro diagnosis using carbonaceous nanoparticles (CNPs). Signal readout is mostly based on fluorometry, electrochemistry and colorimetry, respectively. Besides, the fabrication and separation strategies of CNPs are also demonstrated.

Characterization of a novel bacteriophage specific to Exiguobacterium indicum isolated from a plateau eutrophic lake.

Exiguobacterium is a versatile genus with potential in industry and agriculture. No bacteriophage that infects Exiguobacterium has been reported, despite its potential impacts on the utilization of Exiguobacterium. E. indicum EI9 was isolated from Dianchi Lake, a plateau eutrophic lake in China, which can significantly inhibit the growth of Microcystis aeruginosa. To isolate and characterize Exiguobacterium-infecting bacteriophage, a virulent bacteriophage, DCEIV-9 that specifically infects E. indicum EI9 was isolated from Dianchi lake water sample. DCEIV-9 produced tiny, round, and clear plaques with 0.5-1 mm in diameter. Electron microscopy showed that DCEIV-9 is a typical representative of the Siphoviridae, with an icosahedral head (56 nm in diameter) and a non-contractile tail (163 nm in length). Based on a one-step growth curve, latent period of 20 min and burst size of 51 PFU/infected cell were determined. DCEIV-9 was sensitive to temperature over 50 °C and prefers acid environment. DCEIV-9 was extremely sensitive to proteinase K, chloroform, ethanol, Triton X-100 but not sensitive to SDS. Restriction endonucleases analysis indicated that DCEIV-9 is a dsDNA virus. DCEIV-9 can only infect E. indicum, indicates that it has a narrow host range. DCEIV-9 is a potential new species.

Direct Monitoring of Cell Membrane Vesiculation with 2D AuNP@MnO2 Nanosheet Supraparticles at the Single-Particle Level.

We herein demonstrate robust two-dimensional (2D) UFO-shaped plasmonic supraparticles made of gold nanoparticles (AuNPs) and MnO2 nanosheets (denoted as AMNS-SPs) for directly monitoring cell membrane vesiculation at the single-particle level. Because the decorated MnO2 nanosheets are ultrathin (4.2 nm) and have large diameters (230 nm), they are flexible enough for deformation and folding for parceling of the AuNPs during the endocytosis process. Correspondingly, the surrounding refractive index of the AuNPs increases dramatically, which results in a distinct red-shift of the localized surface plasmon resonance (LSPR). Such LSPR modulation provides a convenient and accurate means for directly monitoring the dynamic interactions between 2D nanomaterials and cell membranes. Furthermore, for the endocytosed AMNS-SPs, the subsequent LSPR blue-shift induced by etching effects of reducing molecules is promising for exploring the local environment redox states at the single-cell level.

Planar Is Better: Monodisperse Three-Layered MoS2 Quantum Dots as Fluorescent Reporters for 2,4,6-Trinitrotoluene Sensing in Environmental Water and Luggage Cases.

In this study, we present a simple but effective fluorescent system for highly sensitive and versatile sensing of 2,4,6-trinitrotoluene (TNT) using few layered planar MoS2 quantum dots (QDs) as reporters. Excitation-independent emitting MoS2 QDs were first fabricated by using the proposed ultrasonic-hydrothermal-based top-down method assisted by carbon-free hydroxylamine hydrochloride. The obtained pristine MoS2 QDs were then modified with cysteine for introducing amino groups as TNT binding sites. The as-prepared MoS2 QDs possess a planar structure, which can more adequately interact with flat aromatic TNT molecules due to π-π attraction and decreased steric effects, compared with traditional spherical/quasi-spherical QDs. As a result, they exhibit extremely high sensitivity for TNT sensing (1 nM and 2 ng for solution and substrate assay, respectively). The common ions containing in environmental water samples do not interfere with the sensing. Furthermore, the QDs-decorated test paper shows an instantaneous (within 1 min) response to trace amounts of deposited TNT, and the fluorescence quenching can even be well-visualized by the naked eye. Because of favorable analytical performances, the proposed MoS2 QDs-based TNT sensing system has potential applications in both environmental water monitoring and security screening.

Salt-tolerant and plant-growth-promoting bacteria isolated from high-yield paddy soil.

Growth and productivity of rice is negatively affected by soil salinity. However, some salt-tolerant bacteria improve the health of plants under saline stress. In this study, 305 bacteria were isolated from paddy soil in Taoyuan, China. Among these, 162 strains were tested for salt-tolerance; 67.3%, 28.4%, and 9.3% of the strains could grow in media with NaCl concentrations of 50, 100, and 150 g/L, respectively. The phylogenic analysis of 74 of these 162 strains indicates that these bacteria belong to Bacillales (72%), Actinomycetales (22%), Rhizobiales (1%), and Oceanospirillales (4%). Among 162 strains, 30 salt-tolerant strains were screened for their plant-growth-promoting activities under axenic conditions at 3, 6, 9, and 12 g/L NaCl; 43%-97% of the strains could improve rice germination energy or germination capacity, while 63%-87% of the strains could increase shoot and root lengths. Among various plant-growth-promoting bacteria, TY0307 was the most effective strain for promoting the growth of rice, even at high salt stress. Its promotor effects were associated with its production of 1-aminocyclopropane-1-carboxycarboxylate deaminase, indole acetic acid, and siderophores; induction of proline accumulation; and reduction of the salt-induced malondialdehyde content. These results suggest that several strains isolated from paddy soil could improve rice salt tolerance and may be used in the development of biofertilizer.

Concurrent catalytic removal of typical volatile organic compound mixtures over Au-Pd/α-MnO2 nanotubes.

α-MnO2 nanotubes and their supported Au-Pd alloy nanocatalysts were prepared using hydrothermal and polyvinyl alcohol-protected reduction methods, respectively. Their catalytic activity for the oxidation of toluene/m-xylene, acetone/ethyl acetate, acetone/m-xylene and ethyl acetate/m-xylene mixtures was evaluated. It was found that the interaction between Au-Pd alloy nanoparticles and α-MnO2 nanotubes significantly improved the reactivity of lattice oxygen, and the 0.91wt.% Au0.48Pd/α-MnO2 nanotube catalyst outperformed the α-MnO2 nanotube catalyst in the oxidation of toluene, m-xylene, ethyl acetate and acetone. Over the 0.91wt.% Au0.48Pd/α-MnO2 nanotube catalyst, (i) toluene oxidation was greatly inhibited in the toluene/m-xylene mixture, while m-xylene oxidation was not influenced; (ii) acetone and ethyl acetate oxidation suffered a minor impact in the acetone/ethyl acetate mixture; and (iii) m-xylene oxidation was enhanced whereas the oxidation of the oxygenated VOCs (volatile organic compounds) was suppressed in the acetone/m-xylene or ethyl acetate/m-xylene mixtures. The competitive adsorption of these typical VOCs on the catalyst surface induced an inhibitive effect on their oxidation, and increasing the temperature favored the oxidation of the VOCs. The mixed VOCs could be completely oxidized into CO2 and H2O below 320°C at a space velocity of 40,000mL/(g·hr). The 0.91wt.% Au0.48Pd/α-MnO2 nanotube catalyst exhibited high catalytic stability as well as good tolerance to water vapor and CO2 in the oxidation of the VOC mixtures. Thus, the α-MnO2 nanotube-supported noble metal alloy catalysts hold promise for the efficient elimination of VOC mixtures.

Three-in-One: Sensing, Self-Assembly, and Cascade Catalysis of Cyclodextrin Modified Gold Nanoparticles.

We herein present a three-in-one nanoplatform for sensing, self-assembly, and cascade catalysis, enabled by cyclodextrin modified gold nanoparticles (CD@AuNPs). Monodisperse AuNPs 15-20 nm in diameter are fabricated in an eco-friendly way by the proposed one-step colloidal synthesis method using CD as both reducing agents and stabilizers. First, the as-prepared AuNPs are employed as not only scaffolds but energy acceptors for turn-on fluorescent sensing based on guest replacement reaction. Then, the macrocyclic supramolecule functionalized AuNPs can be controllably assembled and form well-defined one- and two-dimensional architectures using tetrakis(4-carboxyphenyl)porphyrin as mediator. Finally, in addition to conventional host-guest interaction based properties, the CD@AuNPs possess unpredictable catalytic activity and exhibit mimicking properties of both glucose oxidase and horseradish peroxidase simultaneously. Especially, the cascade reaction (glucose is first catalytically oxidized and generates gluconic acid and H2O2; then the enzymatic H2O2 and preadded TMB (3,3',5,5'-tetramethylbenzidine) are further catalyzed into H2O and oxTMB, respectively) is well-achieved using the AuNPs as the sole catalyst. By employing a joint experimental-theoretical study, we reveal that the unique catalytic properties of the CD@AuNPs probably derive from the special topological structures of CD molecules and the resulting electron transfer effect from the AuNP surface to the appended CD molecules.

Optical sensing and biosensing based on non-spherical noble metal nanoparticles.

Non-spherical noble metal nanoparticles (NPs) have widely tunable localized surface plasmon resonance, very high extinction coefficient, and strongly facet-dependent adsorption/binding properties. A few non-spherical noble metal NPs have been employed as reporters and/or modulators for various optical sensing. This review summarizes recent progress in the study of design, performance, and application of colorimetric and fluorescent sensing/biosensing systems based on three kinds of non-spherical noble metal NPs with different dimension, namely, one- (or quasi-one) dimensional nanorods, two-dimensional nanoplates, and three-dimensional nanodendritics; furthermore, the future developments in this research area are also discussed.

Enzymatic reaction modulated gold nanorod end-to-end self-assembly for ultrahigh sensitively colorimetric sensing of cholinesterase and organophosphate pesticides in human blood.

We present herein the first reported self-assembly modulation of gold nanorods (AuNRs) by enzymatic reaction, which is further employed for colorimetric assays of cholinesterase (ChE) and organophosphate pesticides (OPs) in human blood. ChE catalyzes its substrate (acetylthiocholine) and produces thiocholine and acetate acid. The resulting thiols then react with the tips of the AuNRs by S-Au conjunction and prevent subsequent cysteine-induced AuNR end-to-end (EE) self-assembly. Correspondingly, the AuNR surface plasmon resonance is regulated, which results in a distinctly ratiometric signal output. Under optimal conditions, the linear range is 0.042 to 8.4 µU/mL, and the detection limit is as low as 0.018 µU/mL. As ChE is incubated with OPs, the enzymatic activity is inhibited. So, the cysteine-induced assembly is observed again. On the basis of this principle, OPs can be well determined ranging from 0.12 to 40 pM with a 0.039 pM detection limit. To our knowledge, the present quasi pU/mL level sensitivity for ChE and the quasi femtomolar level sensitivity for OPs are at least 500 and 7000 times lower than those of previous colorimetric methods, respectively. The ultrahigh sensitivity results from (1) the rational choice of anisotropic AuNRs as building blocks and reporters and (2) the specific structure of the enzymatic thiocholine. Because of ultrahigh sensitivity, serum samples are allowed to be extremely diluted in the assay. Accordingly, various nonspecific interactions, even from glutathione/cysteine, are well avoided. So, both ChE and OPs in human blood can be directly assayed without any prepurification, indicating the simplicity and practical promise of the proposed method.

Arenimonas taoyuanensis sp. nov., a novel bacterium isolated from rice-field soil in China.

A Gram-stain negative, aerobic, rod-shaped bacterial strain, YN2-31A(T), was isolated from rice-field soil, Taoyuan Village, Yunnan province of China. The bacterium was observed to grow at 20-45 °C (optimum 28 °C), at pH 5.0-10.0 (optimum 7.0), and in the presence of 0-2% (w/v) NaCl (optimum 0-1%). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain YN2-31A(T) is most closely related to Arenimonas daejeonensis DSM 18060(T) (96.1%), Arenimonas malthae DSM 21305(T) (95.9%), Arenimonas donghaensis DSM 18148(T) (95.1%), Arenimonas composti DSM 18010(T) (94.8%) and Arenimonas maotaiensis JCM 19710(T) (94.8%). The major cellular fatty acids (>10%) were found to be iso-C(18:1) ω9c, iso-C(15:0), Sum In Feature 3 (C(16:1) ω7c/C(16:1) ω6c), and C(16:0). The major ubiquinone was identified as Q-8 and the major cellular polar lipids were identified as diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and unidentified phospholipids. The genomic DNA G+C content was determined to be 72.3 mol%. The results of the phylogenetic, genetic, phenotypic and chemotaxonomic analyses suggest that strain YN2-31A(T) represents a novel species of the genus Arenimonas, for which the name Arenimonas taoyuanensis sp. nov. is proposed. The type strain is YN2-31A(T) (=DSM 26777(T) = CCTCC AB2012964(T)).

Synthesis-modification integration: one-step fabrication of boronic acid functionalized carbon dots for fluorescent blood sugar sensing.

In this paper, we have presented a novel strategy to fabricate fluorescent boronic acid modified carbon dots (C-dots) for nonenzymatic blood glucose sensing applications. The functionalized C-dots are obtained by one-step hydrothermal carbonization, using phenylboronic acid as the sole precursor. Compared with conventional two-step fabrication of nanoparticle-based sensors, the present "synthesis-modification integration" strategy is simpler and more efficient. The added glucose selectively leads to the assembly and fluorescence quenching of the C-dots. Such fluorescence responses can be used for well quantifying glucose in the range of 9-900 µM, which is 10-250 times more sensitive than that of previous boronic acid based fluorescent nanosensing systems. Due to "inert" surface, the C-dots can well resist the interferences from various biomolecules and exhibit excellent selectivity. The proposed sensing system has been successfully used for the assay of glucose in human serum. Due to simplicity and effectivity, it exhibits great promise as a practical platform for blood glucose sensing.

Compact hybrid (gold nanodendrite-quantum dots) assembly: plasmon enhanced fluorescence-based platform for small molecule sensing in solution.

In this study, we have presented a novel plasmon enhanced fluorescence (PEF) system for label-free sensing of small molecules in bulk solution. The amine-terminated gold nanodendrite (AuND) and carboxyl-terminated QDs directly assemble each other by amine-carboxyl attraction. Without any spacer layers, PEF can be increased by 4 times during the formation of the compact hybrid (AuND-QDs) assembly. Both experiment and finite-difference time domain calculation results indicate that the distinct solution-PEF effect is ascribed to two reasons: (1) The used AuNDs simultaneously possess four features in morphology and topology, well-defined superstructure, sharp tips and edges, moderately elongated subunits, and smaller size. (2) The hybrid (AuND-QDs) assembly has a very compact structure. So, the fluorescence is well enhanced by the effective increase of excitation and radiative decay rates with the decrease of scattering effect. The (AuND-QDs) assembly is then employed for sensing of trinitrotoluene (TNT), one of the highly explosive and environmentally detrimental substances, in bulk solution. The sensing principle is that the analytes can react with primary amines on the AuND surface and form Meisenheimer complexes, which break the preformed assemblies and result in the fluorescence recovery of the QDs. The linear range is 0-8.8 nM with 0.05 nM detection limit. The present quasi-picomole level sensitivity is one of the best results for fluorescent TNT sensing. The developed method is successfully applied to TNT sensing in real environmental samples, indicating the practical potential.

From pair to single: sole fluorophore for ratiometric sensing by dual-emitting quantum dots.

Intrinsic dual-emitting doped ZnS:Mn(2+) quantum dots are promising as sole fluorophore for ratiometric sensing. The ratiometric signals are reliably output by three kinds of modulation modes, namely, electron transfer, energy transfer, and chemical reaction, respectively. Compared with a conventional QD-based pair-fluorophore system, such a comprehensively ratiometric signal readout from a single fluorophore not only means a fundamental breakthrough but will substantially simplify the design and greatly promote the application of ratiometric sensing.