Construction of dual Z-scheme Bi2WO6/g-C3N4/black phosphorus quantum dots composites for effective bisphenol A degradation.

In this work, a novel dual Z-scheme Bi2WO6/g-C3N4/black phosphorus quantum dots (Bi2WO6/g-C3N4/BPQDs) composites were fabricated and utilized towards photocatalytic degradation of bisphenol A (BPA) under visible-light irradiation. Optimizing the content of g-C3N4 and BPQDs in Bi2WO6/g-C3N4/BPQDs composites to a suitable mass ratio can enhance the visible-light harvesting capacity and increase the charge separation efficiency and the transfer rate of excited-state electrons and holes, resulting in much higher photocatalytic activity for BPA degradation (95.6%, at 20 mg/L in 120 min) than that of Bi2WO6 (63.7%), g-C3N4 (25.0%), BPQDs (8.5%), and Bi2WO6/g-C3N4 (79.6%), respectively. Radical trapping experiments indicated that photogenerated holes (h+) and superoxide radicals (•O2-) played crucial roles in photocatalytic BPA degradation. Further, the possible degradation pathway and photocatalytic mechanism was proposed by analyzing the BPA intermediates. This work also demonstrated that the Bi2WO6/g-C3N4/BPQDs as effective photocatalysts was stable and have promising potential to remove environmental contaminants from real water samples.

Photoelectrochemical determination of cardiac troponin I based on rod-like g-C3N5@MnO2 heterostructure.

Rod-like graphite carbon nitride@MnO2 (R-g-C3N5@MnO2) heterostructure was prepared by in situ self-anchored growth of MnO2 nanosheet on the surface of R-g-C3N5. The synthesized R-g-C3N5@MnO2 heterostructure as photoactive material exhibited excellent photoelectrochemical (PEC) performance, and the prepared heterostructure-aptamer probe displayed sensitive PEC response to cTnI. Therefore, the PEC method was developed to detect cTnI based on the R-g-C3N5@MnO2 heterostructure. It was found that the linear response to cTnI was in the range 0.001-30 ng/mL under optimized conditions, and the detection limit of the proposed sensor was 0.3 pg/mL. The PEC method displays stable photocurrent response up to 8 cycles and exhibited outstanding selectivity and sensitivity. The PEC method was successfully applied to detect cTnI in serum samples. The recoveries of cTnI detection in serums reach 95.5-104%, and the relative standard deviations range from 3.20 to 4.45%.

g-C3N5-dots as fluorescence probes prepared by an alkali-assisted hydrothermal method for cell imaging.

Carbon nitride materials have become one of the highly explored carbon-based nanomaterials due to their unique properties. Herein, the novel graphitic carbon nitride quantum dots (g-C3N5-dots) were synthesized using an alkali-assisted hydrothermal method. The proposed strategy was simple, time-saving and the entire synthetic process only takes 60 min. And the prepared g-C3N5-dots showed excellent dispersion and good stability in water. What is more, the g-C3N5-dots displayed bright blue fluorescence with a high quantum yield of 12%. It was found that the g-C3N5-dots exhibited peroxidase-like activity, good biocompatibility and low cytotoxicity and can be successfully applied in cell imaging. The proposed method opens a new and efficient way for the preparation of fluorescent g-C3N5-dots and facilitates g-C3N5-dots for bioimaging and related biological sensing applications.

Vanadium carbide MXene: as a reductant for the synthesis of gold nanoparticles and its biosensing application.

Vanadium carbide MXene (V2C) acts as a new type of two-dimensional (2D) graphene-like transition metal material that has attracted research interest. V2C has been widely used in various fields due to its excellent physical and chemical properties. Herein, the self-assembled V2C@gold nanoparticles (V2C@AuNPs) are prepared by water bath process at 80 °C. With the addition of glutathione (GSH), the absorbance (Abs.) at 550 nm of V2C@AuNPs was decreased. Therefore, an optical sensor is developed to detect GSH based on the properties of V2C@AuNPs. Under the optimal conditions, the detection range is 1-32 µM and the detection limit is 0.099 µM. Furthermore, the proposed GSH sensor exhibits high sensitivity, high selectivity, strong stability, and excellent recovery. The work will expand the application of V2C in biosensing.

Cerium-based nanoparticles triggered catalytic reaction for the colorimetric and ratiometric fluorimetric dual-signal sensing of vitamin C.

The construction of multi-modal detection methods has attracted widespread attention in the field of biosensing due to their high sensitivity and strong anti-interference ability. In this manuscript, we developed colorimetric and ratiometric fluorescence dual-signal optical methods based on cerium-based nanoparticles (Ce NPs) for the sensitive detection of vitamin C (VC). The catalysis of Ce NPs with excellent peroxidase-like activity upon the reaction of H2O2 with OPD was occurred, promoting the oxidation of o-phenylenediamine (OPD) to generate 2,3-diaminophennazine (OPDox) with an obvious absorption peak at 420 nm and an emission peak at 565 nm. In the presence of VC, VC not only inhibited the generation of OPDox, but also induced the formation of quinoxaline with an obvious absorption peak at 336 nm and an emission peak at 430 nm. This can be visually observed and monitored by measuring the absorbance of peak at 336 nm (A336) and the ratiometric fluorescence intensity (F430/F565). Therefore, the dual-signal methods are constructed for the detection of VC. The detection lower detection limits are 8.0 µM and 8.4 µM when using the fluorescence and colorimetric signals, respectively. Furthermore, the proposed methods are successfully applied to the detection of VC in practical samples with satisfactory results.

Construction and application of BiOCl/Cu-doped Bi2S3 composites for highly efficient photocatalytic degradation of ciprofloxacin.

In this work, a novel BiOCl/Cu-doped Bi2S3 photocatalyst was designed to efficiently remove ciprofloxacin (CIP) with high photocatalytical activity and good stability over a wide pH range. Compared with Cu-doped Bi2S3, Bi2S3, BiOCl, BiOCl/Bi2S3, and Cu-doped BiOCl, the photocatalytical degradation rate of CIP (97.1% at 20 mg/L) over BiOCl/Cu-doped Bi2S3 was enhanced by about 84.77, 44.23, 2.95, 2.27, and 1.96 times within 20 min, respectively. Notably, the BiOCl/Cu-doped Bi2S3 photocatalyst also displayed high photocatalytical performance in the degradation of other antibiotics including norfloxacin, ofloxacin, and tetracycline (40 mL, 20 mg/L; 88.3%, 100%, and 95.2% of degradation rate within 30 min, respectively) under visible light irradiation. Radical trapping experiments and electron spin resonance technique indicated that superoxide radicals (•O2-) and photogenerated holes (h+) played crucial roles in the photocatalytic degradation of CIP. Finally, the possible CIP degradation pathways was proposed by detecting the CIP intermediates in photocatalytical reaction process.

Aptamer functionalized and reduced graphene oxide hybridized porous polymers SPE coupled with LC-MS for adsorption and detection of human α-thrombin.

In this study, reduced graphene oxide (rGO) hybridized high internal phase emulsions were developed and polymerized as porous carriers for aptamer (5'/5AmMC6/-AGT CCG TGG TAG GGC AGG TTG GGG TGA CT-3') modification to enrich human α-thrombin from serum. The structure and properties of the materials were confirmed by scanning electron microscope (SEM), Fourier transform infrared spectroscope (FT-IR), and X-ray photoelectron spectra (XPS). The adsorption ability and selectivity were studied and the thrombin was detected with liquid chromatography-mass spectrometry (LC-MS). The adsorption of thrombin onto the sorbent was achieved within 30 min and the desorption was realized using 5.0 mL of acetonitrile/water (80/20, v/v). The thrombin was quantified by LC-MS according to its characteristic peptide sequence of ELLESYIDGR.

Electrospun graphene oxide/MIL-101(Fe)/poly(acrylonitrile-co-maleic acid) nanofiber: A high-efficient and reusable integrated photocatalytic adsorbents for removal of dye pollutant from water samples.

The electrospun graphene oxide/MIL-101(Fe)/poly(acrylonitrile-co-maleic acid) nanofibers (E-spun GO/MIL-101(Fe)/PANCMA NFs) were fabricated by a facile electrospinning method and used as integrated photocatalytic adsorbents (IPAs) to remove dye pollutant from water samples. Compared with E-spun GO/PANCMA and E-spun MIL-101(Fe)/PANCMA NFs, the fabricated E-spun GO/MIL-101(Fe)/PANCMA NFs exhibited higher adsorption ability and excellent photocatalytic activity towards a model pollutant Rhodamine B (RhB). Under the optimized conditions, the as-prepared IPAs achieved almost complete adsorption of RhB within 15 min with the maximum adsorption capacity of 10.46 mg/g. Under visible-light irradiation, 93.7% of RhB in 20 mL water sample was degraded within 20 min, and the degradation kinetics of RhB fitted well with the first-order kinetic model. In addition, LC-MS analysis of the RhB degradation products confirmed the degradation pathways, and the generated •OH radicals played important roles in the degradation process. Importantly, the E-spun GO/MIL-101(Fe)/PANCMA NFs exhibited good reusability and could be reused for consecutive 20 cycles, which make them promising candidate materials in the field of industrial applications and environmental remediation.

Fabrication and application of a MIL-68(In)-NH2 incorporated high internal phase emulsion polymeric monolith as a solid phase extraction adsorbent in triazine herbicide residue analysis.

In this work, a metal-organic framework MIL-68(In)-NH2 incorporated high internal phase emulsion polymeric monolith (MIL-68(In)-NH2/polyHIPE) was prepared and applied as a solid phase extraction adsorbent for the extraction and detection of trace triazine herbicides in environmental water samples by coupling with HPLC-UV detection. The fabricated material showed good adsorption for simazine, prometryn, and prometon in water samples because of π-π interactions and hydrogen bonding interactions. Under optimal conditions, the maximum adsorption capacity of simazine, prometon and prometryn was 800 µg g-1, 800 µg g-1 and 6.01 mg g-1, respectively. The linearities were 10-800 ng mL-1 for simazine, prometon and prometryn. The limits of detection were 31-97 ng L-1, and the recoveries were 85.6-118.2% at four spiked levels with relative standard deviations lower than 5.0%. The method has a high sensitivity for the determination of three triazine herbicides in environmental water samples.

Recent advances in separation applications of polymerized high internal phase emulsions.

Polymerized high internal phase emulsions as highly porous adsorption materials have received increasing attention and wide applications in separation science in recent years due to their remarkable merits such as highly interconnected porosity, high permeability, good thermal and chemical stability, and tailorable chemistry. In this review, we attempt to introduce some strategies to utilize polymerized high internal phase emulsions for separation science, and highlight the recent advances made in the applications of polymerized high internal phase emulsions for diverse separation of small organic molecules, carbon dioxide, metal ions, proteins, and other interesting targets. Potential challenges and future perspectives for polymerized high internal phase emulsion research in the field of separation science are also speculated at the end of this review.

Preparation of porous polymers based on high internal phase emulsion for enrichment of estrogens in urine.

In this work, graphene oxide-hybridized high internal emulsion polymers with crosslinking and open-cell structure was prepared and applied for separation and enrichment of estrogens. The prepared graphene oxide-hybridized high internal emulsion polymer monoliths had hydrophobicity, porosity and stability, which were just obtained by one step in-situ emulsion polymerization of 2-ethylhexyl acrylate, glycidyl methacrylate, and divinylbenzene after doping with graphene oxide. Benefit from the advantages of its unique character, the graphene oxide-hybridized high internal emulsion polymers monolith with low background pressure (85 kPa) and high mechanical strength could be applied for efficient separation for trace estrogens in urine. Under the optimized condition, trace estrogens, including estrone, estradiol, and diethylstilbestrol in urine, were detected by high-performance liquid chromatography, all the sample preparation process were carried out in 15 min, the recovery rate was ranged from 85.0 to 106.0% and the relative standard deviation was less than 4.

Spatial Distribution of Endogenous Molecules in Coffee Beans by Atmospheric Pressure Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging.

Mass spectrometry imaging (MSI) is a promising chemical imaging method. Among various endogenous molecules, mapping the concentration and the spatial distribution of specific compounds in the coffee bean tissue is of tremendous significance in its function research, as these compounds are critical to grading coffee beans at the molecular level, determining the geographical origin, and optimizing storage conditions of coffee beans. In this paper, we established an atmospheric pressure (AP) matrix-assisted laser desorption/ionization (MALDI) MSI method for the microscopic distribution analysis of endogenous molecules, for example, sucrose, caffeine, and caffeoylquinic acid, in the coffee bean endosperm. Experiments were done on the differences between coffee beans from eight countries. Principal component analysis (PCA) was performed using IMAGEREVEAL software. The results showed that the chemical composition and relative content of coffee beans from different origins are different. Our work provides a detection method that may be used for coffee bean quality identification, efficient use, product traceability, and product counterfeiting.

Transforming glucose into fluorescent graphene quantum dots via microwave radiation for sensitive detection of Al3+ ions based on aggregation-induced enhanced emission.

This paper initially describes a nanosensor for fluorescence detection of Al3+ ions by using graphene quantum dots (GQDs) that are synthesized via microwave-assisted single-step ring-closure condensation of glucose molecules. The one-pot synthesis strategy based on the microwave radiation could be finished in several minutes and no post-modification of the GQDs was required. In particular, the GQD nanoprobes showed a sensitive and specific fluorescence enhancement response to Al3+. The involved mechanism might be the Al3+-mediated aggregation of the GQDs leading to aggregation-induced enhanced emission (AIEE). Under optimal conditions, this new fluorescent nanosensor was able to quantitatively detect Al3+ in a linear concentration range of 0.4-500 µM. The limit of detection was estimated to be ∼59.8 nM according to the 3σ rule, which made it be among the most sensitive systems currently available for sensing the target ion. Moreover, satisfactory recovery results (ranging from 96.8 to 109.7%) of analyzing a set of real water examples additionally validated its accuracy for practical applications. Considering its simplicity, high sensitivity and specificity, low cost, and good reliability, the developed fluorescent nanosensing system for Al3+ holds great promise for broad uses in water safety, environmental monitoring, and waste management.

Recent advances of ambient ionization mass spectrometry imaging in clinical research.

The structural information and spatial distribution of molecules in biological tissues are closely related to the potential molecular mechanisms of disease origin, transfer, and classification. Ambient ionization mass spectrometry imaging is an effective tool that provides molecular images while describing in situ information of biomolecules in complex samples, in which ionization occurs at atmospheric pressure with the samples being analyzed in the native state. Ambient ionization mass spectrometry imaging can directly analyze tissue samples at a fairly high resolution to obtain molecules in situ information on the tissue surface to identify pathological features associated with a disease, resulting in the wide applications in pharmacy, food science, botanical research, and especially clinical research. Herein, novel ambient ionization techniques, such as techniques based on spray and solid-liquid extraction, techniques based on plasma desorption, techniques based on laser desorption ablation, and techniques based on acoustic desorption were introduced, and the data processing of ambient ionization mass spectrometry imaging was briefly reviewed. Besides, we also highlight recent applications of this imaging technology in clinical researches and discuss the challenges in this imaging technology and the perspectives on the future of the clinical research.

Assembly and application advancement of organic-functionalized graphene-based materials: A review.

Owing to the remarkable physicochemical properties such as hydrophobicity, conductivity, elasticity, and light weight, graphene-based materials have emerged as one of the most appealing carbon allotropes in materials science and chemical engineering. Unfortunately, pristine graphene materials lack functional groups for further modification, severely hindering their practical applications. To render graphene materials with special characters for different applications, graphene oxide or reduced graphene oxide has been functionalized with different organic agents and assembled together, via covalent binding and various noncovalent forces such as π-π interaction, electrostatic interaction, and hydrogen bonding. In this review, we briefly discuss the state-of-the-art synthetic strategies and properties of organic-functionalized graphene-based materials, and then, present the prospective applications of organic-functionalized graphene-based materials in sample preparation.

A porous carbon absorbent based on high internal phase emulsion for separation and enrichment of trifluralin from soil.

A porous carbon absorbent was obtained by using high internal phase emulsions (HIPEs) polymerization followed by high temperature carbonization under nitrogen protection. Graphene oxide (GO) and silica nanoparticles were doped into the HIPEs to enhance the adsorption ability and reusability. Fourier infrared spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy were used for characterization and several parameters of separation and enrichment of trifluralin. The results showed that a hyper-crosslink framework material was obtained with abundant porous (pore size of about 30 µm) and a good adsorption and separation efficiency. The adsorption rate was up to 100% and trifluralin was completely eluted from the absorbent by 2.0 mL of an acetic acid-acetonitrile mixture. Graphical abstractSchematic representation of synthesis of porous carbon absorbent by GO and SiO2 doped HIPEs.POLYHIPES-GO&SiO2: Polymerized High Internal Phase Emulsions doped with Silica and Graphene oxide.

Electrospun reduced graphene oxide/TiO2/poly(acrylonitrile-co-maleic acid) composite nanofibers for efficient adsorption and photocatalytic removal of malachite green and leucomalachite green.

Electrospun reduced graphene oxide/TiO2/poly(acrylonitrile-co-maleic acid) composite nanofibers (E-spun RGO/TiO2/PANCMA NFs) were fabricated using electrospinning of the dispersive solution of PANCMA, GO and TiO2 followed by post-chemical reduction. The obtained composite nanofibers were compressed in a dialyzer and then used to absorb and degrade malachite green (MG) and leucomalachite green (LMG) from aqueous solution. Compared to the E-spun TiO2/PANCMA and GO/TiO2/PANCMA NFs, the E-spun RGO/TiO2/PANCMA NFs exhibited higher adsorption capacity and photocatalytic degradation ability. Under optimized conditions, 90.6% of MG and 93.7% of LMG from 50 mL aqueous sample solution were adsorbed on the RGO/TiO2/PANMA NFs (3.0 mg fibers) in 2.0 min, and subsequent the 91.4% and 95.2% of MG and LMG adsorbed on the NFs were degradated in 60 min under UV irradiation, respectively. In addition, the E-spun RGO/TiO2/PANMA NFs exhibited good reusability and could be reused in multiple cycles of operations for adsorption and photocatalytic degradation of MG and LMG. This work demonstrated that the electrospun composite nanofibers are promising materials for removal of pollutants from environmental water samples.

Development of sulfur doped carbon quantum dots for highly selective and sensitive fluorescent detection of Fe2+ and Fe3+ ions in oral ferrous gluconate samples.

Sulfur-doped carbon quantum dots (S-CQDs) with stable blue fluorescence were synthesized through a facile one-step hydrothermal method by using ascorbic acid and thioglycolic acid as carbon and sulfur sources. The prepared S-CQDs exhibited a sensitive and selective response to Fe3+ ions in comparison with Fe2+ and other metal ions, In the presence of adequate H2O2, Fe2+ was completely transformed to Fe3+ that is the determinable form of iron ions, and the difference in the change of the fluorescence intensity of S-CQDs before and after adding H2O2 was used for detection of Fe2+ and Fe3+ ions, respectively. Under the optimum experimental conditions, the fluorescence intensity of S-CQDs gradually decreased with increasing of Fe3+ concentration ranging from 0 to 200 µM. Good linearity was achieved over the range of 0-200 µM. The detection limit of the developed method was 0.050 µM for Fe3+. The recoveries of Fe2+ and Fe3+ spiked in real samples ranged from 98.2% to 112.4%. Finally, the proposed S-CQDs integrated with Fenton system was applied to the detection of Fe2+ and Fe3+ ions in oral ferrous gluconate samples, which presents potential applications in the speciation and determination of Fe2+ and Fe3+ ions in complex samples.

Novel porous carbon composites derived from a graphene-modified high-internal- phase emulsion for highly efficient separation and enrichment of triazine herbicides.

In this study, novel porous carbon composites were successfully prepared with graphene-modified high-internal-phase emulsions (HIPEs) via a simple process of polymerization followed by carbonization. The morphology of the macroporous composites was observed and the verification of structural and functional groups were verified by scanning electron microscopy (SEM), and other characterizations techniques including Fourier transform infrared (FI-IR), X-ray photoelectron spectroscopy (XPS) spectra and Raman spectroscopy. The prepared porous carbon composites were applied to farmland water for the simultaneous adsorption of triazine herbicides and the conditions of extraction and desorption were optimized. Due to the π-π interaction and hydrophobic interaction between triazine herbicides and carbon composites, the maximum adsorption capacity of simazine, prometon and prometryn were 33.4, 34.5 and 33.8 µg g-1, respectively. Adsorption and desorption of triazine herbicides can be achieved in 10 min, and high-speed mass transfer was observed. The calibration curves of three triazine herbicides were linear (R2 ≥0.9996) in the range from 25.0 to 500.0 ng mL-1. The LOD of three triazine herbicides by using the proposed SPE-HPLC-DAD method were 2.5-5.6 ng mL-1. All the results suggest that these materials may be useful for more efficient hazardous residue separations.

Magnetic stir cake sorptive extraction of trace tetracycline antibiotics in food samples: preparation of metal-organic framework-embedded polyHIPE monolithic composites, validation and application.

In this work, a novel Fe3O4@Cu3(btc)2-embedded polymerized high internal phase emulsion (Fe3O4@HKUST-1-polyHIPE) monolithic cake was synthesized, characterized and used as an adsorbent in the magnetic stir cake sorptive extraction (MSCSE) and determination of tetracycline antibiotics (TCs) in food samples by a combination of with high-performance liquid chromatography-fluorescence detection (HPLC-FLD). The prepared Fe3O4@HKUST-1-polyHIPE monolithic composites displayed a strong extraction ability and high column capacity due to enhanced interactions such as π-π interactions, hydrogen bonding, and electrostatic interactions. The extraction and desorption conditions were evaluated, and the calibration curves of four spiked TCs were linear (R2 ≥ 0.9991) in the range from 20 to 800 ng mL-1 for milk and egg samples, and 20 to 800 ng g-1 for chicken muscle and kidney samples. The limits of detection and the limits of quantification of the four TCs by using the proposed MSCSE-HPLC-FLD method were in the range of 1.9-4.6 and 5.5-13.9 ng mL-1 for milk and egg samples, and 1.8-3.7 and 5.3-13.0 ng g-1 for chicken muscle and kidney samples, respectively. The recoveries of the target TCs from spiked food samples were in the range from 86.6 to 110.7% with relative standard deviations lower than 7.0%. The proposed method was successfully applied for the determination of these four TCs in milk, egg, chicken muscle, and kidney samples.