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Pyrolysis has created many (and will open more) possibilities for high-value utilization of biomass. To obtain the optimal amount of desired pyrolysis products, especially high-quality bio-oil, a g...

Background Wheat is one of three major food crops in China. Alternaria species can cause spoilage of wheat with consequent mycotoxin accumulation. Alternariol (AOH), alternariol monomethyl ether (AME), and tenuazonic acid (TeA) are the most common and frequently studied mycotoxins. There are limited regulations placed on Alternaria mycotoxin concentrations worldwide due to the lack of toxicity data available. More data on the levels of mycotoxin contamination are also needed. It is also important to reduce the risks of Alternaria mycotoxins. Results One hundred and thirty-two wheat samples were collected from Hebei Province, China, and analyzed for AOH, AME, and TeA. Tenuazonic acid was found to be the predominant Alternaria mycotoxin, especially in flour samples. Studying Alternaria species that cause black-point disease of wheat indicated that Alternaria alternata and Alternaria tenuissima were the dominant species. Most of the Alternaria strains studied produced more than one mycotoxin and TeA was produced at the highest concentration, which may have resulted in the high level of TeA contamination in the wheat samples. Furthermore, magnolol displayed obvious antifungal and antimycotoxigenic activity against Alternaria. This is the first report on the antimycotoxigenic activity of magnolol against Alternaria species. Conclusion The Alternaria mycotoxin contamination levels in wheat and wheat products from Hebei Province, China, were correlated with the toxigenic capacity of the Alternaria strains colonizing the wheat. Considering its safety, magnolol could be developed as a natural fungicide in wheat, or as a natural alternative food preservative based on its strong antifungal and antimycotoxigenic activity against Alternaria strains. © 2020 Society of Chemical Industry.

Nitrogen doping is a promising method for the preparation of functional carbon materials. In this study, a nitrogen-doped porous coral biochar was prepared by using bamboo as raw material, urea as nitrogen source, and KHCO3 as green activator through in-situ pyrolysis. The structure of the obtained biochar was characterized by various techniques including nitrogen adsorption and desorption, Raman spectroscopy, X-ray photoelectron spectrometer, and etc. The adsorption properties of nitrogen-doped biochar were evaluated with phenol and methylene blue probes. The results showed that the nitrogen source ratio had a significant effect on the evolution of pore structure of biochar. Low urea addition ratio was beneficial to the development of pore structures. The optimum specific surface area of nitrogen-doped biochar could be up to 1693 m2·g-1. Nitrogen doping can effectively improve the adsorption capacity of biochar to phenol and methylene blue. Biochar prepared at 973.15 K with low urea addition ratio exhibited the highest adsorption capacity for phenol and methylene blue, and the equilibrium adsorption capacity was 169.0 mg·g-1 and 499.3 mg·g-1, respectively. By comparing the adsorption capacity of various adsorbents in related fields, it is proved that the nitrogen-doped biochar prepared in this study has a good adsorption effect.

Two-photon fluorescent (TPF) probes, which allow imaging of biological events in a high spatiotemporal resolution, are in great demand. Recently, carbon quantum dots (CQDs) have emerged as a promising class of TPF probes. Unfortunately, the use of the existing CQDs has been limited by their weak TPF capacities. Herein, we report the first facile and large-scale synthesis of nitrogen-rich CQDs (NRCQDs) based on a donor-π-acceptor (D-π-A) strategy. The resulting NRCQDs demonstrated a tremendous TPF capacity with a two-photon absorption cross section (TPACS) and quantum yield (QY) up to 61 200 Göppert-Mayer (GM) units and 63%, respectively, which is greater than those that could be achieved by the existing TPF carbon probes. Structural and optical analyses of NRCQDs revealed that the great TPF capacity is contributed by the nitrogen-rich D-π-A structure as well as the high crystallinity, large plane, rigid, graphitic nitrogen-doped π-conjugated system. We further demonstrated that NRCQDs allow imaging of live cells as well as live liver tissues at depths of up to 440 μm. Our results suggest NRCQDs as a robust TPF probe that can be potentially used for a variety of biological applications.

Laccase mimics are multicopper oxidase highly important for biotechnology and environmental evaluation/remediation. However, buffer species-dependent catalytic activity is rarely investigated. Herein, through Cu

In terms of how the signal varies in response to increased concentration of an analyte, sensors can be classified as either "signal-on" or "signal-off" format. While both types hold potentials to be sensitive, selective, and reusable, in many situations "signal-on" sensors are preferred for their low background signal and better selectivity. In this study, with the detection of lysozyme using its DNA aptamer as a trial system, for the first time we demonstrated that such an aptamer-based electrochemical biosensor can be converted from intrinsically "signal-off" to "signal-on" with the aid of a DNA exonuclease. The fact that the stepwise cleavage of antilysozyme aptamer catalyzed by Exonuclease I (Exo I) is entirely inhibited upon binding lysozyme leads to the selective removal of unbound DNA probes (thiolate anti-lysozyme DNA aptamer strands immobilized on gold electrode) upon the introduction of Exo I to the sensor. With the aid of electrostatically bound redox cations ([Ru(NH3)6]3+), we were able to quantitate the number of aptamer strands that are bound with lysozymes via conventional cyclic voltammetry (CV) measurements. We demonstrated that Exo I-assisted signal-on conversion protocol not only improves the sensing performance (10 times better limit of detection) but also promises a versatile strategy for DNA-based biosensor design, i.e., it can be readily adapted to other aptamer-protein binding systems (thrombin, as another example).

Strategies for selectively imaging and delivering drugs to tumours typically leverage differentially upregulated surface molecules on cancer cells. Here, we show that intravenously injected carbon quantum dots, functionalized with multiple paired α-carboxyl and amino groups that bind to the large neutral amino acid transporter 1 (which is expressed in most tumours), selectively accumulate in human tumour xenografts in mice and in an orthotopic mouse model of human glioma. The functionalized quantum dots, which structurally mimic large amino acids and can be loaded with aromatic drugs through π–π stacking interactions, enabled—in the absence of detectable toxicity—near-infrared fluorescence and photoacoustic imaging of the tumours and a reduction in tumour burden after the targeted delivery of chemotherapeutics to the tumours. The versatility of functionalization and high tumour selectivity of the quantum dots make them broadly suitable for tumour-specific imaging and drug delivery., Intravenously injected functionalized carbon quantum dots that bind to the large neutral amino acid transporter 1 and that structurally mimic large amino acids selectively accumulate in human tumours in mice, facilitating targeted theranostics.

Large doses of anticancer drugs entering cancer cell nuclei are found to be effective at killing cancer cells and increasing chemotherapeutic effectiveness. Here we report red-emissive carbon quantum dots, which can enter into the nuclei of not only cancer cells but also cancer stem cells. After doxorubicin was loaded at the concentration of 30 μg/mL on the surfaces of carbon quantum dots, the average cell viability of HeLa cells was decreased to only 21%, while it was decreased to 50% for free doxorubicin. The doxorubicin-loaded carbon quantum dots also exhibited a good therapeutic effect by eliminating cancer stem cells. This work provides a potential strategy for developing carbon quantum-dot-based anticancer drug carriers for effective eradication of cancers.

Co-based metal organic frameworks (ZIF-67), working as an oxidase-mimicking nanozyme, can simultaneously catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) and Amplex red, exhibiting a high catalytic activity. For Amplex red, two consecutive redox reactions are reported, which is specifically applied for fluorescence "turn-on" detection of biothiols.

As one of the most promising nanomaterials for biomedical applications, carbon dots (CDs) hold great potential in the field of bioimaging, biosensing and biotherapy due to their low cytotoxicity, high water solubility, favorable biocompatibility, good photostability, tunable fluorescence emission and excitation. In this review, we will provide an update on the latest research of CDs on the synthetic routes, chemical modifications, optical properties and biomedical applications. We will mainly discuss their applications in bioimaging of normal and cancer stem cells and tumour cells, two-photon fluorescence imaging, in vivo imaging, biosensing, and cancer therapy including photothermal therapy, photodynamic therapy and chemotherapy. At the end, current challenges and future perspectives of CDs in biomedical applications will also be discussed. We hope that this review will provide valuable insights to inspire new discoveries on CDs and draw a roadmap towards a broader range of biomedical applications.

Cation exchange has been a successful methodology for tuning the bandgaps of nanomaterials, while the most popular protocol in the toluene/methanol system lacks precise compositional control due to its inherent poor solvent compatibility. We herein report an alternative cation exchange route in N,N-dimethylformamide (DMF) solvent for converting preformed colloidal CdTe nanowires into CdxM1-xTe (M = Pb2+, Zn2+, Ag+, Hg2+) nanowires with good batch-to-batch reproducibility. The resulting CdxM1-xTe nanowires show a tunable bandgap from 2.26 to 0.63 eV, and the energy levels of these nanowires can be finely tuned. Furthermore, a comparative study for the cation exchange of CdTe nanowires with Pb2+ ions in toluene/methanol and DMF illustrated that the reduction of Cd2+ extraction and the Pb2+ introduction barrier accounts for precise compositional control. The cation exchange reaction in the DMF phase provides an efficient way to obtain nanomaterials with precise composition control. Moreover, these available high-quality colloidal semiconductor nanowires also pave the way for near-infrared device exploration.

N-doped biochar with a high nitrogen content and tuned pore structure was obtained from Pinus sylvestris by an in-situ pyrolysis process with simultaneous doping nitrogen and activation where urea was used as a nitrogen precursor and NaHCO3 was employed as the activator. To test the feasibility of N-doped biochars obtained under different pyrolysis temperatures as catalyst supports, a series of Ru catalysts were prepared for use in the methanation and the catalysts were labelled as Ru/N-ABC-x, where x represented the pretreatment temperatures(500, 600 and 700 °C). Besides, the catalytic test of Ru/ABC which was prepared under the same conditions without N modification was also conducted for comparison. The probe reaction test of CO2 methanation showed that the Ru/N-ABC-600 catalyst with the highest pyridinic-N (37.7%) content had superior or comparable catalytic performance to Ru/N-ABC-500 and Ru/N-ABC-700 prepared from N-doped biochar with different pyridinic-N content. A high CO2 conversion of 93.8% with a CH4 selectivity of 99.7% was achieved on Ru/N-ABC-600 under the optimum reaction conditions (380 °C, 1 MPa, n(H2)/n(CO2) of 4, with a gas hourly space velocity of 6000 mL·g-1·h-1). This work provides an effective strategy for the utilization of biochar to develop highly active catalysts for CO2 methanation.

Nitrogen-doped hierarchical porous biochar has aroused great interest in energy storage and adsorption applications. In this study, nitrogen-doped hierarchical porous biochar was prepared from corn...

Carbon quantum dots (CQDs) have developed into prospective nanomaterials for next-generation lighting and displays due to their intrinsic advantages of high stability, low cost, and environmental friendliness. However, confined by the spin-forbidden nature of triplet state transitions, the highest theoretical value of external quantum efficiency (EQE) of fluorescent CQDs is merely 5%, which fundamentally limits their further application in electroluminescent light-emitting diodes (LEDs). Soluble phosphorescent CQDs offer a means of breaking the shackle to achieve efficient monochromatic electroluminescence, especially red emission, which is a pivotal constituent in full-color displays. Here, the synthesis of red (625 nm) phosphorescent carbon quantum dot organic frameworks (CDOFs) with a quantum yield of up to 42.3% and realization of high-efficiency red phosphorescent electroluminescent LEDs are reported. The LEDs based on the CDOFs exhibited a red emission with a maximum luminance of 1818 cd m-2 and an EQE of 5.6%. This work explores the possibility of a new perspective for developing high-performance CQD-based electroluminescent LEDs.

Metal-organic frameworks (MOFs) as a peroxidase mimic have been integrated with glucose oxidase (GOx) to achieve one-step glucose detection. However, limited by the loading amount of GOx, the performances of the developed glucose sensing assays still remain to be further improved to meet sensing requirements in diverse biological samples. Herein, with Fe3+ as the metal ion and 2-amino-benzenedicarboxylic acid as a ligand, a fluorescent Fe-based organic framework (NH2-MIL-101) with peroxidase-like activity was synthesized. Due to the large specific surface area (791.75 m2 g-1), 68 μg mg-1 GOx could be immobilized through the amidation coupling reaction, and the product was designated GOx@NH2-MIL-101. With OPD as the substrate, Gox@NH2-MIL-101 achieved highly efficient biomimetic cascade catalysis for one-step glucose detection through an inner filter effect: upon reacting with glucose, GOx@NH2-MIL-101 catalytically oxidized glucose using dissolved O2, and the produced H2O2 concurrently oxidized o-phenylenediamine (OPD) to oxidized OPD (oxOPD), accompanied by the fluorescence of GOx@NH2-MIL-101 at 456 nm being quenched and that of oxOPD at 565 nm being enhanced. With the fluorescent ratio F565/F456 used as a readout signal, a wide linear range of 0.1-600 μM was obtained, and the detection limit was 0.0428 μM. Based on the excellent selectivity and high stability of GOx@NH2-MIL-101, the developed assay was successfully applied to glucose detection in human serum and saliva, presenting potential applications in diverse biological samples and even medical diagnosis.

Due to severely overlapping emission and or/ excitation spectra of polycyclic aromatic hydrocarbons (PAHs), the specifically recognizing PAHs by the fluorescent technique is still a challenge. Here, synthesized Ag@SiO2 nanoparticles with 40 ± 4 nm Ag core and 7 ± 1 nm SiO2 shell performing as a nanoprobe could selectively recognize 2-aminoanthracene (2-AA) via metal-enhanced fluorescence (MEF) within 2 min. The sensing mechanism was based on the facts: (1) there was a perfect spectral overlap between the local surface plasmon resonance (LSPR) peak of Ag@SiO2 and the absorptive peak of 2-AA, and (2) 2-AA could interact with Ag@SiO2 nanoparticles through hydrogen bonds between –NH2 in 2-AA and –OH in SiO2 shell. As a result, with Ag@SiO2 nanoparticles as a nanoprobe, a fluorescent assay for detecting 2-AA was developed with a linear range from 1 nM to 800 nM, which exhibited an excellent selectivity over possible PAHs, dyes and metal ions. The detection limit was 1 nM. Finally, the developed assay was applied to analyse 2-AA in industrial wastewater samples, which were highly consistent with that of high performance liquid chromatography (HPLC). This study presents a feasible assay for detecting 2-AA for environmental monitoring and toxic evaluating.

DNA G-quadruplex (G4) could adopt multiple conformations, and the exact conformation is related to the presence of cations. However, the fact that cations with various concentrations could competitively bind with G4 is rarely investigated, which greatly limits the potential applications of G4-based sensors. Here, with PW17 (a G4-forming DNA sequence) as an example, Na+ and K+ with different concentrations competitively binding with PW17 are clarified by circular dichroism spectroscopy and electrospray ionization mass spectroscopy. Although Na+ could induce PW17 switching to unstable and antiparallel Na+-stabilized PW17 (2Na+-PW17) ( CNa+ = 5-70 mM) and further to stable and hybrid 2Na+-PW17 ( CNa+ = 70-800 mM), K+ ( CK+ = 0.1-10 mM) could replace Na+ in 2Na+-PW17 with 2Na+-PW17 transforming into K+-stabilized PW17 (2K+-PW17). Moreover, the replacing ability strictly relied on CK+ and CNa+. In the switching process, a stable intermediate including a K+ and an Na+ in one G4 (K+-Na+-PW17) is firstly detected. Importantly, the stable K+-Na+-PW17 is detected at 0.5 mM K+ and 140 mM Na+. Based on the facts, the interferences of Na+ with the performance of PW17-based K+ sensors are investigated. With the stable K+-Na+-PW17 as a sensing probe and protoporphyrin IX (PPIX) as a G4 fluorescent read-out probe, a linear relationship between CK+ (500 nM-10 mM) and PPIX fluorescence is observed, which provides a fluorescence assay for detecting K+ with the co-existing 140 mM Na+. This study exhibits clear evidence of Na+ and K+ competitively binding with G4 and finds a novel and stable K+-Na+-PW17, which provides a clue to further explore G4 functions in Na+-contained samples.

High-performance white light-emitting diodes (WLEDs) hold great potential for the next-generation backlight display applications. However, achieving highly efficient and stable WLEDs with wide-color-gamut has remained a formidable goal. Reported here is the first example of pure red narrow bandwidth emission triangular CQDs (PR-NBE-T-CQDs) with photoluminescence peaking at 610 nm. The PR-NBE-T-CQDs synthesized from resorcinol show high quantum yield (QY) of 72% with small full width at half maximum of 33 nm. By simply controlling the reaction time, pure green (PG-) NBE-T-CQDs with high QY of 75% were also obtained. Highly efficient and stable WLEDs with wide-color-gamut based on PR- and PG-NBE-T-CQDs was achieved. This WLED showed a remarkable wide-color gamut of 110% NTSC and high power efficiency of 86.5 lumens per Watt. Furthermore, such WLEDs demonstrate outstanding stability. This work will set the stage for developing highly efficient, low cost and environment-friendly WLEDs based on CQDs for the next-generation wide-color gamut backlight displays.

As crystalline semiconductor nanowires are thinned down to a single-unit-cell thickness, many fascinating properties could arise pointing to promising applications in various fields. A grand challenge is to be able to controllably synthesize such ultrathin nanowires. Herein, we report a strategy, which synergizes a soft template with oriented attachment (ST-OA), to prepare high-quality single-unit-cell semiconductor nanowires (SSNWs). Using this protocol, we are able to synthesize for the first time ZnS and ZnSe nanowires (NWs) with only a single-unit-cell thickness (less than 1.0 nm) and a cluster-like absorption feature (i.e., with a sharp, strong, and significantly blue-shifted absorption peak). Particularly, the growth mechanism and the single-unit-cell structure of the as-prepared ZnS SSNWs are firmly established by both experimental observations and theoretical calculations. Thanks to falling into the extreme quantum confinement regime, these NWs are found to only absorb the light with wavelengths shorter than 280 nm (i.e., solar-blind UV absorption). Utilizing such a unique property, self-powered photoelectrochemical-type photodetectors (PEC PDs) based on the ZnS SSNWs are successfully fabricated. The PDs after interface modification with TiO2 exhibit an excellent solar-blind UV photoresponse performance, with a typical on/off ratio of 6008, a detectivity of 1.5 × 1012 Jones, and a responsivity of 33.7 mA/W. This work opens the door to synthesizing and investigating a new dimension of nanomaterials with a wide range of applications.

Three trimethylsilyl based malonate esters, bis(trimethylsilyl) 2-methyl-2-fluoromalonate (BTMSMFM), bis(trimethylsilyl) 2-ethyl-2-fluoromalonate (BTMSEFM) and bis(trimethylsilyl) 2-propyl-2-fluoromalonate (BTMSPFM), have been used as additives in 1.0 M LiPF6/ethylene carbonate (EC)-dimethyl carbonate (DMC)-diethyl carbonate (DEC) (1-1-1, by v) baseline electrolyte for LiNi0.80Co0.15Al0.05O2 (NCA) based high voltage lithium ion batteries. The NCA half-cells with 5 wt% BTMSMFM exhibit higher capacity retention than that in the baseline electrolyte at different upper cut off voltages, that is, 4.2, 4.3, 4.4 and 4.5 V vs. Li/Li+. Scanning electron microscope (SEM) show that the additive successfully prevents the formation of thick solid electrolyte interphase (SEI) films on the surface of the NCA electrodes. X-ray diffraction (XRD) further reveals that the crystal structure of NCA is also maintained in the electrolyte with 5 wt% BTMSMFM at high cut off voltages. Besides beneficial to NCA cathode, the BTMSMFM additive also ensures better cycling performance of the graphite based half-cells and NCA/graphite full-cells, and thus is a promising additive for application in rechargeable lithium ion batteries.

An ultrabroad-band solid white emission from carbon quantum dot aggregation with a full width at half maximum over 200 nm throughout the entire visible light window and, even better, with a sufficient red component is first reported. UV pumped WLEDs are fabricated by integrating phosphors onto a UV-LED chip, and they show favorable warm white light characteristics with CIE coordinates of (0.42, 0.38) and a 91 high color rendering index.

Here, we found that Thioflavin T (ThT) could specifically bind with a G-GGG unit (named as "Guanine Island") in double stranded DNA (ds-DNA). Through stacking with G base via hydrogen bonds, the rotation of ThT was restricted and concurrently its planarization was enforced. Such a binding mode produced a significantly enhanced ThT fluorescence. Based on this discovery, with ThT as a lighting-up probe for "Guanine Island" in ds-DNA, the fluorescent detection of single-nucleotide mutation (C mutation) was investigated. With C base in target DNA mutating to G, A or T and further hybridizing with a probe DNA containing a GGG unit at the mutated point, ds-DNA including G-GGG, A-GGG or T-GGG islands was formed, respectively. After binding with ThT, C mutation was clearly recognized. With C mutating to G as an example, the detection limit was as low as 3 nM. Importantly, the developed assay could be applied to recognize C mutating to G in a DNA sequence related to dilated cardiomyopathy for diluted human serum. As a sensing unit ("Guanine Island" in ds-DNA lighting up ThT), it is expected to be applied for various biological or environmental systems.

Blue-yellow fluorescence–phosphorescence dual emission from single-component white emissive W-CNQDs with a high PLQE of 25% is reported for the first time., Developing efficient single-component white light-emitting diodes (WLEDs) is extremely challenging due to the issue of Kasha's rule. Here we report the first demonstration of blue-yellow fluorescence–phosphorescence dual emission from our newly minted single-component white emissive carbon nitride quantum dots (W-CNQDs). The W-CNQDs deliver an overall photoluminescence quantum efficiency of 25%, which is the highest value among white-emitting materials reported to date, based on utilizing both singlet and triplet states. Experimental and theoretical investigations reveal that the carbonyl groups at the rim of the W-CNQDs play a key role in promoting intersystem crossing and inducing intermolecular electronic coupling, affording intensive yellow phosphorescence. Efficient white emission is achieved with a phosphorescence quantum efficiency of 6% under ambient conditions. A WLED is fabricated by integrating W-CNQD phosphors into a UV-LED chip, which shows favorable white light characteristics with CIE coordinates and a CRI of (0.35, 0.39) and 85, respectively, demonstrating good color chromatic stability. This work opens up new opportunities for exploring dual emission mechanisms and designs to facilitate the development of efficient single-component WLEDs.

Here, hollow CdS nanoboxes (average size of 120 nm) with graded nanovoids (ranging from 2 nm to 13 nm) distributed in the walls (average thickness of 20 nm) are in situ synthesized through directly sulfurizing a Cd metal-organic framework (Cd-MOF-47) with thiourea. A specific surface area of 153 m2 g-1 is achieved. With as-prepared hollow CdS nanoboxes as photocatalysts for water splitting to H2 (visible light irradiation), H2 evolution rate is as high as 21 654 μmol g-1 h-1, which is nearly 79 times higher than that of bulk CdS. Such an excellent photocatalytic efficiency is ascribed to the large specific surface area for improving light absorbability and the porous nanostructure for efficiently utilizing excitation light due to the multiple scattering within the hollow framework. Moreover, a smaller band gap (2.30 eV) with a higher conduction band (-0.83 V) presents a strong reducibility, which is beneficial for reducing H2O to H2. A combination of fluorescence spectroscopy (PL), PL lifetimes and the photoelectrochemical technique shows that hollow CdS nanoboxes exhibit lower fluorescence intensity, longer electron lifetime and stronger photocurrent intensity than bulk CdS, implying an improved separation and transfer of photoinduced charge carriers. This work presents a novel methodology to prepare hollow nanostructures, exhibiting potential applications in the field of energy conversion.

As an emerging class of luminescent nanomaterials, carbon quantum dots (CQDs) have recently shown enormous potential for optoelectronic applications on account of their characteristic broad emission, tunable fluorescence emission, high thermal stability, and low cytotoxicity. In this review, we will update the latest research progress achieved in CQDs, including their synthesis, optical properties, luminescence mechanism, and applications in optoelectronics. Mainly reviewed here are their room temperature phosphorescence, delayed fluorescence properties, as well as their optoelectronic applications including light-emitting diodes, lasing, solar cells, and photodetectors. Finally, current problems and challenges of CQD-based optoelectronics applications are discussed with an eye on future development. We hope that this review will provide critical insights to inspire new exciting discoveries in the area of CQDs from both fundamental and practical standpoints so that the realization of their potential in the optoelectronic areas can be facilitated.

The design and testing of integrated colorimetric microarray immunochips (immuno-microarrays) are reported for the quantitation and direct visual determination of multiple illicit drugs (e.g., morphine, cocaine and amphetamine) in body fluids. Such an immuno-microarray platform utilizes a competitive immunoassay format, which is based on silver staining for quantitative detection and multicolor staining for direct visualization (i.e., qualitative identification) of analytes present in the sample. Under optimized conditions, the dynamic response ranges of 3.7–1000, 1.1–300 and 1.5–300 ng mL−1 were achieved for amphetamine, cocaine, and morphine, respectively, which are wider towards low concentrations than those of standard enzyme-linked immunosorbent assay (ELISA) tests. The limits of detection (LODs) for morphine, cocaine, and amphetamine were determined to be 1.5 ± 0.1, 1.1 ± 0.1 and 3.7 ± 0.2 ng mL−1, respectively in oral fluids, which meet government regulations for law enforcement. The obvious advantages of multiplexing, simultaneous visual recognition, and accurate quantitation make the on-site detection feasible, confirming that such a colorimetric immuno-microarray holds promise for practical applications.

Identifying the species and concentrations of antioxidants is really important because antioxidants play important roles in various biological processes and numerous diseases. Compared with an individual sensor detecting a single antioxidant with limited specificity, a sensor array could simultaneously identify various antioxidants, in which 3-5 types of nanomaterials with peroxidase-like activity are absolutely necessary. Herein, as a single-atom nanozyme, Fe-N/C with oxidase-mimicking activity was applied to construct a triple-channel colorimetric sensor array: (1) Fe-N/C catalytically oxidized three substrates 3,3',5,5'-tetramethylbenzidine (TMB), 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) and o-phenylenediamine (OPD) to produce blue oxidized TMB (oxTMB), green oxidized ABTS (oxABTS) and yellow oxidized OPD (oxOPD), respectively; (2) with oxTMB, oxABTS and oxOPD as three sensing channels, a colorimetric sensor array was constructed for simultaneously discriminating glutathione (GSH), l-cysteine (l-Cys), ascorbic acid (AA), uric acid (UA), and melatonin (MT), even quantifying concentrations (with GSH as a model analyst). The performance of the sensor array was validated through accurately identifying 15 blind samples containing GSH, l-Cys, AA, UA and MT in buffer solution and human serum samples, and also in binary and ternary mixtures. This work proved that fabricating a single nanozyme-based sensor array was a simplified and reliable strategy for simultaneously probing multiple antioxidants.

As an environmentally friendly and renewable alternative fuel, biomethane can be obtained from biogas upgrading; however, the commercial technologies for upgrading are currently an unsustainable global process by releasing CO2 into the atmosphere. Here, this research proposed a novel sustainable method for direct biogas upgrading to high-quality biomethane by catalytic CO2 methanation and focused on the performance improvement of Ni-based catalysts. Carbon nanotubes-silica fiber (CNT-SF) composite as a high-heat transfer fibrous support was successfully synthesized using the Ni/silica fiber (SF) catalyst as a core-fiber seeding structure in ethanol steam reforming. The Ni/CNT-SF catalyst was extensively characterized and investigated in the direct biogas upgrading by CO2 methanation. The results revealed that Ni/CNT-SF catalyst exhibited superior catalytic performance than the Ni/SF and conventional Ni/silica porous (SP) catalysts. This suggested that the Ni/CNT-SF catalyst easily accessed the reactant molecules and exhibited an enhanced metal-support interaction with smaller Ni crystalline size, leading to a higher dispersion of the Ni active site, enhancing the CO2 methanation. Furthermore, the addition of Mg (1–3%wt.) into the Ni/CNT-SF catalyst resulted in a stronger metal-support interaction and increased moderate basic sites, which could suppress the Ni sintering and promote the adsorption and activation of CO2. Under optimum conditions (350 °C, 10 bar, H2/CO2 molar ratio of 4, and GHSV of 24,000 mL⋅g−1⋅h−1), the Ni-2Mg/CNT-SF catalyst achieved the highest CO2 conversion, CH4 selectivity, producing high-quality biomethane with CH4 content at approximately 95%, without CH4 losses.

Photocatalysis has been facing challenging problems especially the inefficient photocarriers transfer at the interfaces. Here, based on Ksp difference, we prepare the sequential heterojunction of CoS/CdS/CuS via sequential cation exchange strategy, and propose the concept of "electron-welcome zone", where the point-to-point contact can be formed at the interface, thus providing continuous electron transport channels. HAADF-STEM EDS line test indicates the formation of designed structures, and the p/n junction is confirmed by band structure and Mott-Schottky analysis. Theoretical calculation indicates that CoS reduces the Gibbs free energy of the reaction. TRPL spectra show that the existence of "electron welcome zone" greatly improves the lifetime of electrons. This sequential structure enable the optimal H2 production rate to reach 123.2 mmol g−1 h−1 with AQE of 45.6%, which is among the highest values of CdS-based photocatalysts. This work opens new way to efficient photogenerated carrier transfer channel for solar-energy conversion.

Precise vehicle localization is a basic and critical technique for various intelligent transportation system (ITS) applications. It also needs to adapt to the complex road environments in real-time. The global positioning system and the strap-down inertial navigation system are two common techniques in the field of vehicle localization. However, the localization accuracy, reliability and real-time performance of these two techniques can not satisfy the requirement of some critical ITS applications such as collision avoiding, vision enhancement and automatic parking. Aiming at the problems above, this paper aims to propose a precise vehicle ego-localization method based on image matching.,This study included three steps, Step 1, extraction of feature points. After getting the image, the local features in the pavement images were extracted using an improved speeded up robust features algorithm. Step 2, eliminate mismatch points. Using a random sample consensus algorithm to eliminate mismatched points of road image and make match point pairs more robust. Step 3, matching of feature points and trajectory generation.,Through the matching and validation of the extracted local feature points, the relative translation and rotation offsets between two consecutive pavement images were calculated, eventually, the trajectory of the vehicle was generated.,The experimental results show that the studied algorithm has an accuracy at decimeter-level and it fully meets the demand of the lane-level positioning in some critical ITS applications.

As the performance of hairpin DNA (hpDNA)-based biosensors is highly dependent on the yield of stem-loop (hairpin) conformations, we report herein a versatile fluorometric in situ hybridization protocol for examining hpDNA self-assembled monolayers (SAMs) on popularly used biochip substrates. Specifically, the ratio of fluorescence (FL) intensities of hpDNA SAMs (in an array format) before and after hybridization was adopted as the key parameter for performing such a determination. Upon confirming the existence of mixed and tunable DNA conformations in binary deposition solutions and efficient hybridization of the hairpin strands with the target DNA via gel electrophoresis assays, we tested the fluorometric protocol for determining the coverages of hpDNA in hpDNA/ssDNA SAMs prepared on gold; its accuracy was validated by Exonuclease I (Exo I)-assisted electrochemical quantitation. To further confirm its versatility, this FL protocol was adopted for quantifying hairpin conformations formed on glass and polycarbonate (PC) substrates. The molar ratios of surface-tethered hairpin conformations on the three different substrates were all found to be proportional to but less than those in the binary deposition solutions, and were dependent on the substrate morphology. The findings reported herein are beneficial for the construction of highly efficient DNA hairpin-based sensing surfaces, which essentially facilitates the creation of hpDNA-based biosensors with optimal detection performance.

Biochar is a carbon-rich product obtained from the thermo-chemical conversion of biomass. Studying the evolution properties of biochar by in-situ modification or post-modification is of great significance for improving the utilisation value of lignocellulosic biomass. In this paper, the production methods of biochar are reviewed. The effects of the biomass feedstock characteristics, production processes, reaction conditions (temperature, heating rate, etc.) as well as in-situ activation, heteroatomic doping, and functional group modification on the physical and chemical properties of biochar are compared. Based on its unique physicochemical properties, recent research advances with respect to the use of biochar in pollutant adsorbents, catalysts, and energy storage are reviewed. The relationship between biochar structure and its application are also revealed. It is suggested that a more effective control of biochar structure and its corresponding properties should be further investigated to develop a variety of biochar for targeted applications.

Numerous studies have reported cation-dependent stability and topological changes of G-quadruplexes (G4s), but competitions between cations at different concentrations for binding with G4s and thei...

Cation exchange has been a successful methodology for tuning the bandgaps of nanomaterials, while the most popular protocol in the toluene/methanol system lacks precise compositional control due to its inherent poor solvent compatibility. We herein report an alternative cation exchange route in

Carbon quantum dots (CQDs) have emerged as promising materials for optoelectronic applications on account of carbon’s intrinsic merits of high stability, low cost, and environment-friendliness. However, the CQDs usually give broad emission with full width at half maximum exceeding 80 nm, which fundamentally limit their display applications. Here we demonstrate multicolored narrow bandwidth emission (full width at half maximum of 30 nm) from triangular CQDs with a quantum yield up to 54–72%. Detailed structural and optical characterizations together with theoretical calculations reveal that the molecular purity and crystalline perfection of the triangular CQDs are key to the high color-purity. Moreover, multicolored light-emitting diodes based on these CQDs display good stability, high color-purity, and high-performance with maximum luminance of 1882–4762 cd m−2 and current efficiency of 1.22–5.11 cd A−1. This work will set the stage for developing next-generation high-performance CQDs-based light-emitting diodes., Carbon quantum dots have promising advantages such as high stability, low cost and environment-friendliness, but their broad emission band limits their application in displays. Here Yuan et al. synthesize these dots showing tunable emission color, high fluorescence and a narrow FWHM of only 30 nanometers.

To obtain dual active near-infrared (NIR) nanomaterial with strong absorption and emission properties, we report herein a novel precursor reactivity differentiation strategy, i.e., utilizing 1-octadecene (ODE)–Se having the ability to react with Ag salts much stronger and faster than ODE–thiourea, for single-step preparation of Ag2Se@Ag2S nanocrystals (NCs). With this strategy, we were able to synthesize high-quality Ag2Se@Ag2S NCs with both excellent NIR absorption and emission properties. Particularly, these nanocrystals possess a rather strong and sharp excitonic absorption peak with a full width at half maximum less than 70 nm and a maximum fluorescence quantum yield as high as 24.3%. Their appealing optical properties and structural features were founded to be highly dependent on the Se to S precursor ratio in the reaction solutions, owing to such a ratio exerting a direct influence on the core sizes and shell thicknesses of the as-formed NCs. Taking advantage of their remarkable NIR absorption properties, self-powered photoelectrochemical-type photodetectors based on the as-prepared Ag2Se@Ag2S NCs were successfully fabricated, which demonstrate a much better response performance and photostability in comparison with those based on Ag2Se NCs.