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1.
Se Pu ; 39(9): 998-1005, 2021 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-34486839

RESUMO

In this work, a polymer precursor was first synthesized using p-terphenyl (TP) and terephthaloyl chloride (TC) as monomers. Then, cross-linking was realized by means of a Schiff base reaction with melamine (MA) as a modifier to obtain an amine-functionalized porous organic polymer TP-TC-MA. The synthesized polymers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and point of zero charge (pHpzc) measurements, as well as on the basis of nitrogen adsorption-desorption isotherms. Adsorption experiments were carried out to evaluate the adsorption properties of TP-TC-MA for methyl orange (MO), a typical anionic azo dye that has widespread industrial application. The amount of MO adsorbed on TP-TC-MA was evaluated by ultraviolet-visible (UV-Vis) spectroscopy at a wavelength of 463 nm. Microscopic analysis revealed that the as-synthesized polymer had an aggregated particle-shaped structure. XRD spectra confirmed that TP-TC-MA was an amorphous polymer, consistent with the results of high-resolution TEM experiments. The Brunauer-Emmett-Teller (BET) specific surface area and total pore volume of TP-TC-MA were determined as 708.5 m 2/g and 0.556 cm3/g, respectively. The measured pHpzc of TP-TC-MA was 4.0, probably because of the abundant nitrogen-containing groups provided by MA. The factors affecting adsorption, such as pH, adsorbent dosage, contact time, initial pollutant concentration, and ionic strength, were investigated. Because of the protonation of the N-atom in TP-TC-MA, the pH had a strong impact on the adsorption of MO. The removal efficiency could be maximized at the optimized pH of 3.0. The adsorption equilibrium isotherm, measured at 25 ℃ and a concentration of 50-500 mg/L, showed that the MO adsorption over TP-TC-MA followed the Langmuir isotherm, with a maximum adsorption capacity of 156.3 mg/g. The modeling of the experimental adsorption data was consistent with the pseudo-second-order kinetic model, which indicated fast adsorption and chemisorption as the dominant mechanism. With increasing ionic strength, the adsorption of MO slightly decreased, suggesting a partial antagonistic ion effect. Results of the selectivity study revealed that TP-TC-MA was more selective toward MO than methylene blue (MB), which indicated that electrostatic interactions played a significant role during the adsorption progress. Five adsorption-desorption cycles showed that TP-TC-MA could be regenerated without significant deterioration of its adsorption efficiency, indicating that it has good stability and reusability. The observed adsorption performance indicated that this MA-modified porous organic polymer offers prospects for further research and application in the treatment of dye-containing wastewaters.


Assuntos
Polímeros , Poluentes Químicos da Água , Adsorção , Compostos Azo , Concentração de Íons de Hidrogênio , Cinética , Porosidade , Espectroscopia de Infravermelho com Transformada de Fourier , Triazinas , Poluentes Químicos da Água/análise
2.
J Hazard Mater ; 416: 126251, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492994

RESUMO

Due to the nonbiodegradability and accumulation of mercury ion, even in extremely small amount, it will cause varying degrees of harm to environment and human health. Although researchers have developed many strategies to detect and monitor trace Hg2+, only a few provide sensitivities of less than 1.0 pM. Surface Enhanced Raman Spectroscopy (SERS) is a common method to detect mercury ion due to its high sensitivity, rapid detection and easy operation. In this work, we report a new SERS aptasensor based on dual recycling amplification for the detection of trace mercury ion, which combines SERS with nucleic acid signal amplification through functional aptamer and elaborately designed hairpin DNA. Under the optimal experimental conditions, this SERS aptasensor exhibits excellent selectivity and high sensitivity. A linear range (0.2-125 fM) and a low detection limit (0.11 fM) are obtained. By using specific aptamers, the strategy will provide a new idea for the trace detection of toxic contaminants in water environment.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Mercúrio , DNA , Ouro , Humanos , Limite de Detecção , Análise Espectral Raman , Água
3.
Chem Commun (Camb) ; 57(81): 10504-10507, 2021 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-34528033

RESUMO

Here, we propose a cancer cell membrane (CM) coated Au-Fe3O4 complex (AFTP@CM), loaded with tannic acid and phorbol 12-myristate 13-acetate for targeted drug delivery and enhanced chem/photo therapy.

4.
Chem Commun (Camb) ; 57(80): 10343-10346, 2021 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-34528980

RESUMO

Herein, a rapid approach toward the size/morphology-controlled synthesis of [Cu(L-mal)(bipy)·2H2O] (CuLBH) was developed by adjusting the concentrations of 2-methylimidazole (2-MI) and copper ions. The chiral separation efficiency test indicated that the nano-diameter CuLBH exhibited better selective potential towards (±)-1-(1-naphthyl)ethanol (NE) by providing more fully exposed recognition sites. In order to further improve the selectivity for NE enantiomers and avoid the aggregation of MOF nanoparticles, the nanosized CuLBH-decorated carboxylated cellulose (CC) composite CC-CuLBH was designed by controlling the ratio of the solvent and Cu2+, which exhibited much higher enantioselectivity than those of pristine CC and even nano CuLBH.

5.
Nanotechnology ; 32(50)2021 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-34547735

RESUMO

Visible light-driven photoreduction of CO2and H2O to tunable syngas is an appealing strategy for both artificial carbon neutral and Fischer-Tropsch processes. However, the development of photocatalysts with high activity and selectivity remains challenging. For this case, we here design a hybrid catalyst, synthesized byin situdeposition of Ag crystals on GaN nanobelts, that delivers a tunable H2/CO ratio between 0.5 and 3 under visible light irradiation (λ > 400 nm). The obtained photocatalyst delivers a maximal turnover frequency value of 3.85 h-1and a corresponding yield rate of 2.12 mmol h-1g-1for CO production, while the photocatalytic activity keeps stable during five cycling tests. Additionally, syngas can be detected even atλ > 600 nm. Experiments and mechanistic studies reveal that the existence of Ag crystals not only extends the light absorption region but also promotes the charge transfer efficiency, and thereby leading to a photocatalytic improvement. Accordingly, the present work affords an opportunity for developing an efficient photo-driven system by using solar energy to alleviate CO2emissions.

6.
Chemosphere ; 286(Pt 3): 131759, 2021 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-34388433

RESUMO

Considering the complexity of traditional cobalt phosphide (Co2P) loaded biochar synthesis research on a simple and efficient synthesis method has practical significance. In this study, after phosphoric acid activation, Neosinocalamus affinis biochar (NAB) and nanoplate Co3O4 quickly formed a Co2P-NAB composite material with high Co2P crystallinity and was uniformly dispersed on the surface of NAB in a microwave reactor. Co2P-NAB has an excellent catalytic degradation effect in the activation of peroxymonosulfate (PMS) to degrade tetracycline (TC). The optimal TC degradation efficiency was achieved with the addition of 50 mg L-1 TC concentration, 0.2 g L-1 catalysts, 0.406 mM PMS and pH = 6.02. In addition, according to the pseudo-first-order reaction rate constant calculation, the composite of Co2P-NAB and PMS the synergy efficiency is 81.55 %. Compared with Co2P-NAB (10.83 %) and PMS (7.62 %) alone, the Co2P-NAB/PMS system has a significant promotion effect on the degradation of TC molecules. Additionally, the Co2P-NAB/PMS system had a TC mineralization rate of 68 % in 30 min. Furthermore, after a series of characterization, detection and analysis, and influencing factor experiments, we proposed a potential mechanism for the Co2P-NAB/PMS reaction system to degrade TC and found that singlet oxygen (1O2) plays an essential role in the non-radical degradation process. Finally, according to the liquid chromatography-mass spectrometry (LC-MS) detection of TC degradation intermediates, a possible degradation route was proposed. Therefore, this work uses microwave technology to present a novel and simple synthesis method for transition metal phosphides, which provides potential application value for the treatment of actual wastewater with heterogeneous catalysts.

7.
ACS Appl Mater Interfaces ; 13(33): 40070-40078, 2021 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-34387999

RESUMO

Aminothiols are closely related to chronic kidney disease, but little is known regarding levels of related aminothiols in the urine of immunoglobulin A vasculitis with nephritis (IgAVN) patients. Herein, a well-defined core-shell Zr-based metal-organic framework (Zr-MOF) composite SiO2@50Benz-Cys was constructed as a mercury ion affinity material via a solvent-assisted ligand exchange strategy for the selective extraction and enrichment of low-concentration aminothiols in IgAVN patient urine. SiO2@50Benz-Cys was competent to enrich the total glutathione (GSH) and total homocysteine (Hcy) in virtue of the excellent affinity after chelation with mercury ions. The extraction efficiencies were closely related to the pH, dithiothreitol amount, and the dose of functional Zr-MOF. Coupled with HPLC-MS/MS in optimized conditions, GSH and Hcy were determined with low detection limits of 0.5 and 1 nmol L-1, respectively. The recoveries of GSH and Hcy for the urine sample at three spiked levels were in the range of 85.3-105% and 79.5-103%, which showed good precision and accuracy. Benefiting from the matrix interference elimination in the process of extraction, the simultaneous detection of aminothiols in the urine of the healthy group and immunoglobulin A vasculitis (IgAV) and IgAVN patients was successfully carried out, suggesting that the Zr-MOF and the robust method together provided a potential application in the analysis of urinary biomolecules. The analysis of variance (ANOVA) showed that the levels of GSH and Hcy had significant differences between the patients and the control. This work is very valuable as it provides a better understanding of concentration alterations of GSH and Hcy in urine involved with IgAVN for clinical research.


Assuntos
Glutationa/urina , Homocisteína/urina , Estruturas Metalorgânicas/química , Nefrite/diagnóstico , Zircônio/química , Técnicas Biossensoriais , Cromatografia Líquida de Alta Pressão , Humanos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Dióxido de Silício , Coloração e Rotulagem/métodos , Compostos de Sulfidrila/química , Espectrometria de Massas em Tandem
8.
Anal Chim Acta ; 1176: 338772, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34399894

RESUMO

The extraction performance of solid-phase microextraction (SPME) fiber is significantly influenced by coating materials and fabricating process. It is urgently needed for fabricating robust SPME fiber with facile preparation methods. Herein, a novel polyimide (PI) @ covalent organic framework (COF) synthesized by 1,3,5-Tris (4-aminophenyl) benzene (TPB) and 2,5-dimethoxyterephthalaldehyde (DMTP) fiber, named PI@TPB-DMTP fiber, was successfully fabricated with facile method at room temperature. Firstly, a COF crystals TPB-DMTP was in situ grown on stainless steel fiber, where the COF crystals was synthesized by the Schiff-base reaction between TPB and DMTP. Subsequently, the COF coating was covered with an ultrathin layer of PI through a simple dip-coating method to improve the fiber stability. By coupled PI@TPB-DMTP SPME fiber with gas chromatography-negative chemical ion-mass spectrometry (GC-NCI-MS), a sensitive analytical method was established for the determination of ultratrace polybrominated diphenyl ethers (PBDEs) in water sample. To achieve the best efficiency and sensitivity for the analysis of PBDEs, six potential influencing factors in extraction step and desorption step were optimized. Under optimized conditions, the established method showed high enhancement factors of 1470-3555, wide linear range of 0.05-100 ng L-1, low detection limits of 0.0083-0.0190 ng L-1, good repeatability for intra-day in the range of 3.71%-7.62% and inter-day in the range of 5.12%-8.81%, good reproducibility in the range of 6.83%-9.21%. The satisfactory recovery was ranged from 79.2% to 117.3% in determining real water samples. The excellent experimental performance was mainly attributed to the large specific surface area of TPB-DMTP, as well as the high permeability of porous PI film. The results demonstrated that the COF-based fiber showed great potential for analysis of PBDEs in complex environmental samples.


Assuntos
Estruturas Metalorgânicas , Poluentes Químicos da Água , Éteres Difenil Halogenados/análise , Reprodutibilidade dos Testes , Microextração em Fase Sólida , Temperatura , Poluentes Químicos da Água/análise
9.
Anal Chim Acta ; 1176: 338769, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34399896

RESUMO

A novel magnetic borate-modified MXene composite was prepared by in situ growth of Fe3O4 particles onto the surface of phenylboronic acid modified Ti3C2Tx nanosheets. The magnetic composite possesses highly selective recognition properties to catecholamines, and high adsorption capacity (up to 319.6 µmol g-1) for dopamine. Besides, the adsorption of urinary catecholamines can be accomplished within 2.0 min. The excellent adsorption performance can be assigned to its unique 2D layered structures, which helps to shorten the diffusion path and facilitate molecular transport. In addition, the multilayer adsorption and the synergetic interactions of borate affinity, van der Waals forces, hydrogen bonding and π-π stacking also contribute to the adsorption. By coupling the magnetic boronate affinity composites with high-performance liquid chromatography-fluorescence detection, a sensitive method for the determination of catecholamines in urine samples was proposed. The validation results revealed it can offer good linearities (correlation coefficients higher than 99%). The method detection limits were 0.06, 0.16, 0.03 and 0.14 ng mL-1 for norepinephrine, epinephrine, dopamine and isoprenaline, respectively, and relative recoveries for these catecholamines were in the range of 98.56-108.1%, 92.56-110.0%, 98.79-112.3% and 88.14-97.81%, respectively. The proposed method was successfully applied to analyze the catecholamines in the urine samples from 15 healthy volunteers and 16 patients with Alzheimer's disease. The results indicated that the magnetic borate-modified Mxene composite possesses superior extraction performance, and can be used as an outstanding candidate for the extraction of catecholamines in pre-clinical or clinical studies.


Assuntos
Boratos , Catecolaminas , Adsorção , Cromatografia Líquida de Alta Pressão , Humanos , Fenômenos Magnéticos , Magnetismo , Extração em Fase Sólida
10.
ACS Sens ; 6(7): 2691-2699, 2021 07 23.
Artigo em Inglês | MEDLINE | ID: mdl-34237940

RESUMO

i-Motifs are DNA secondary structures present in cytosine-rich sequences. These structures are formed in regulatory regions of the human genome and play key regulatory roles. The investigation of sequences capable of forming i-motif structures at the single-molecule level is highly important. In this study, we used α-hemolysin nanopores to systematically study a series of DNA sequences at the nanometer scale by providing structure-dependent signature current signals to gain in-sights into the i-motif DNA sequence and structural stability. Increasing the length of the cytosine tract in a range of 3-10 nucleobases resulted in a longer translocation time through the pore, indicating improved stability. Changing the loop sequence and length in the sequences did not affect the formation of the i-motif structure but changed its stability. Importantly, the application of all-atom molecular dynamics simulations revealed the structural morphology of all sequences. Based on these results, we postulated a folding rule for i-motif formation, suggesting that thousands of cytosine-rich sequences in the human genome might fold into i-motif structures. Many of these were found in locations where structure formation is likely to play regulatory roles. These findings provide insights into the application of nanopores as a powerful tool for discovering potential i-motif-forming sequences and lay a foundation for future studies exploring the biological roles of i-motifs.


Assuntos
Nanoporos , Sequência de Bases , Citosina , DNA/genética , Humanos , Simulação de Dinâmica Molecular
11.
Chemistry ; 27(53): 13418-13425, 2021 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-34263950

RESUMO

To fulfill the demand of precision and personalized medicine, single-atom catalysts (SACs) have emerged as a frontier in biomedical fields due to enzyme-mimic catalysis. Herein, we present a biocompatible and versatile nanoagent consisting of single-atom iron-containing nanoparticles (SAF NPs), DOX and A549 cell membrane (CM). The designed porous iron-based SACs originally served as a drug-carrying nanoplatform to release DOX selectively in a tumor microenvironment (TME) for chemotherapy (CT) due to their high loading capacity (155 %) for DOX; this signifies that SACs are promising candidates for universal cargo delivery. Besides, the designed single-atom nanoagent can perform like peroxidase, which effectively triggers an in situ tumor-specific Fenton reaction to generate abundant toxic hydroxyl radicals (⋅OH) selectively in the acidic TME for chemodynamic therapy (CDT). With the combination of CDT and CT, the constructed SAF NPs@DOX@CM nanoagent demonstrates better in vivo therapeutic performance than single-pathway therapy. In the meantime, after modification with CM, SAF NPs@DOX@CM can achieve homologous binding to target tumor tissues and avoid early clearance. This study presents a type of multifunctional SACs for enhanced cancer treatment via the capacity of a drug carrier combined with the enzymatic therapies of single-atom catalytic sites.


Assuntos
Nanopartículas , Neoplasias , Catálise , Linhagem Celular Tumoral , Humanos , Peróxido de Hidrogênio , Radical Hidroxila , Microambiente Tumoral
12.
Adv Mater ; 33(33): e2007650, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34197001

RESUMO

The electrochemical method of combining N2 and H2 O to produce ammonia (i.e., the electrochemical nitrogen reduction reaction [E-NRR]) continues to draw attention as it is both environmentally friendly and well suited for a progressively distributed farm economy. Despite the multitude of recent works on the E-NRR, further progress in this field faces a bottleneck. On the one hand, despite the extensive exploration and trial-and-error evaluation of E-NRR catalysts, no study has stood out to become the stage protagonist. On the other hand, the current level of ammonia production (microgram-scale) is an almost insurmountable obstacle for its qualitative and quantitative determination, hindering the discrimination between true activity and contamination. Herein i) the popular theory and mechanism of the NRR are introduced; ii) a comprehensive summary of the recent progress in the field of the E-NRR and related catalysts is provided; iii) the operational procedures of the E-NRR are addressed, including the acquisition of key metrics, the challenges faced, and the most suitable solutions; iv) the guiding principles and standardized recommendations for the E-NRR are emphasized and future research directions and prospects are provided.

13.
J Sep Sci ; 44(18): 3398-3406, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34265181

RESUMO

In this study, a new Ti3 C2 Tx -coated fiber was synthesized and utilized as coatings for solid-phase microextraction of seven polychlorinated biphenyls. The as-produced multilayered Ti3 C2 Tx MXene was characterized by X-ray diffractometer, thermos-gravimetric analysis, scanning electron microscopy, and energy dispersive spectroscopy. It is noteworthy that the Ti3 C2 Tx showed some attractive features including unique 2D layered structures, large surface area, good hydrophilicity, and rich active recognition sites, endowing it has a high affinity towards the target polychlorinated biphenyls. Subsequently, the affecting parameters on the extraction efficiency of polychlorinated biphenyls were optimized. Under the optimal conditions, a novel method for the analysis of polychlorinated biphenyls in water samples was proposed. The Ti3 C2 Tx -coated fiber-based solid-phase microextraction method showed good linearity (r2  > 0.9928), high enrichment factors (268-442), low limits of detection (0.06-0.15 ng/L), and satisfactory repeatability (RSDs < 7.5%) for the polychlorinated biphenyls. The excellent method recoveries were in the range of 90.0-98.4, 92.0-98.2, and 92.0-98.0% for river water, lake water, and tap water samples, respectively. These results suggested that the proposed Ti3 C2 Tx -coated fiber-based method represents a promising alternative for the analysis of polychlorinated biphenyls.

14.
J Chromatogr A ; 1651: 462296, 2021 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-34144400

RESUMO

A 34-membered tetraazahexaphenylmacrocycle (N4Ph6) with a rigid π-conjugated moiety was chemically bonded to silica gel with 3-chloropropyltrimethoxysilane as the coupling agent to prepare a novel SiO2@N4Ph6 stationary phase. Several common organic analytes, including alkylbenzenes, polycyclic aromatic hydrocarbons, anilines, phenols, phthalates, and folic acid, were selected as probes to investigate its chromatographic performance. The as-developed SiO2@N4Ph6 stationary phase showed superiority retention and high selectivity for probe molecules through multiple interactions, including hydrophobic, π-π, hydrogen-bonding, and steric interactions. Density functional theory calculation results using folic acid as model solute provided an intuitive and a quantitative description of the multiple retention mechanisms.


Assuntos
Compostos Aza/química , Compostos Macrocíclicos/química , Teoria da Densidade Funcional , Interações Hidrofóbicas e Hidrofílicas , Fenóis/análise , Hidrocarbonetos Policíclicos Aromáticos/análise , Padrões de Referência , Reprodutibilidade dos Testes , Dióxido de Silício/química , Espectroscopia de Infravermelho com Transformada de Fourier , Eletricidade Estática , Termodinâmica
15.
Artigo em Inglês | MEDLINE | ID: mdl-34157958

RESUMO

A solid-phase extraction (SPE) method was established for fipronil and its metabolite residues (fipronil desulfinyl, fipronil sulphone and fipronil sulphide) in eggs with a covalent triazine framework (CTF) porous material as the adsorbent followed by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) detection. Multiple probes and quantum chemistry theory calculations were conducted to describe the versatile adsorption property directly and quantifiably. The conjugated structure of CTF and N-containing triazine generated π-π interactions and hydrogen bonds between the CTF and the targets, which led to high extraction efficiency and recoveries. The solid-phase extraction parameters, including amount of the adsorbent, type of eluent, amount of eluent and loading rate were investigated. Under the optimal experimental conditions, the recoveries of the analytes were between 85.5% and 103.2%, and the RSD (n = 5) was between 1.8% and 3.6%. The LODs and LOQs were 0.13-0.2 ng g-1 and 0.5-0.8 ng g-1, respectively. The sorbent can effectively reduce the interference of the matrix and meet the detection requirements of fipronil and its metabolites in eggs. These results imply that the CTF as adsorbents have great potential in the analysis of trace targets in samples with complex matrices.

16.
Int J Biol Macromol ; 182: 1759-1768, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-34048839

RESUMO

In this study, zirconium (IV)-impregnated magnetic chitosan graphene oxide (Zr-MCGO) was synthesized for removing fluoride from aqueous solution in batch mode. Characterization approaches (pHpzc, FTIR, SEM, XRD, VSM, Raman, BET, and XPS) proved the successful incorporation of Zr into the adsorbent. Zr-MCGO exhibited a relatively favorable and stable capacity of defluoridation at lower pH with a wide range of pH from 4.0 to 8.0, while there was slightly negative effect of ionic strength on adsorption. In addition, Elovich kinetic model and Koble-Corrigan isotherm model could describe the uptake of fluoride well. The adsorption capacity was 8.84 mg/g at 313 K and Zr-MCGO was easily separated from mixtures using external magnet. Based on the experiments and XPS, electrostatic force, ligand exchange, and Lewis acid-base interaction might be potential adsorption mechanisms. Pseudo-second-order model was more compatible with the desorption process by 0.01 mol/L NaHCO3 solution. Therefore, Zr-MCGO was a promising candidate for defluoridation on wastewater pollution remediation.


Assuntos
Quitosana/química , Fluoretos/isolamento & purificação , Grafite/química , Fenômenos Magnéticos , Água/química , Zircônio/química , Adsorção , Ânions , Concentração de Íons de Hidrogênio , Cinética , Modelos Teóricos , Salinidade , Soluções , Temperatura , Fatores de Tempo
18.
Org Biomol Chem ; 19(20): 4492-4496, 2021 May 26.
Artigo em Inglês | MEDLINE | ID: mdl-33960992

RESUMO

A nickel-catalyzed asymmetric Suzuki-Miyaura cross-coupling of racemic 3-bromo-phthalides and arylboronic acids was realized for the synthesis of diverse chiral 3-aryl-phthalides in moderate to excellent reaction yields. The reaction proceeded in a stereoconvergent manner and high enantioselectivities were observed for most examined examples. A number of functional groups like aldehyde, ester and bromide were well tolerated. Heteroaromatic boronic acids were also competent coupling partners in this reaction.

19.
Talanta ; 231: 122336, 2021 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-33965016

RESUMO

Investigation into monosaccharides is critical for studies of oligosaccharides structure and function in biological processes. However, monosaccharides quantification is still challenge due to their isomeric structure and high hydrophilic properties. Besides, it was difficult to obtain isotopic internal standards (IS) of each monosaccharide in complex matrixes. Herein, we developed a novel strategy for the qualification and quantification of monosaccharides in urine using two structure analogs 1-(4-methylphenyl)-3-methyl-5-pyrazolone (MPMP) and1-phenyl-3-methyl-5-pyrazolone (PMP) as non-isotopically paired labeling (NIPL) reagents by liquid chromatograph-tandem mass spectrometry (LC-MS/MS). The derivatized monosaccharides by NIPL method not only had sufficient retention time differences on reversed-phase column, but also exhibited predominant product ion pairs (m/z 189 & m/z 175) in the multiple reaction monitoring (MRM) mode. In this method, PMP labeled standards were adopted as one-to-one internal standards (ISs). 12 urinary monosaccharides were successfully determined and the linear ranges expanded five orders of magnitude with limit of quantification (LOQ) varied from 0.09 ng mL-1 to 0.36 ng mL-1 as well as the accuracy higher than 98.15% and the relative standard derivation (RSD) lower than 7.92%. With assistance of multivariate analysis, the targeted monosaccharide biomarkers were firstly obtained for the diagnosis of bladder cancer. By the inexpensive NIPL reagents-MPMP/PMP, the developed strategy possessed the specific advantages of low cost, simple operation, high sensitivity and high accuracy for the qualification and quantitation of monosaccharides. As expected, this method will provide an alternative application potential for targeted metabolomics analysis.


Assuntos
Monossacarídeos , Espectrometria de Massas em Tandem , Cromatografia Líquida de Alta Pressão , Cromatografia Líquida , Oligossacarídeos
20.
Micromachines (Basel) ; 12(3)2021 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-33801056

RESUMO

Based on the graphene floating gate, a tunable terahertz metamaterial absorber is proposed. Compared with the traditional graphene-dielectric-metal absorber, our absorber has the property of being non-volatile and capacity for anti-interference. Using the finite element method, the paper investigates the absorption spectra, the electric field energy distribution, the tunability and the physical mechanism. In addition, we also analyse the influence of geometry, polarization and incident angles on the absorption. Simulation results show that the bandwidth of the absorption above 90% can reach up to 2.597 THz at the center frequency of 3.970 THz, and the maximum absorption can be tuned continuously from 14.405% to 99.864% by controlling the Fermi level from 0 eV to 0.8 eV. Meanwhile, the proposed absorber has the advantages of polarization insensitivity and a wide angle, and has potential applications in imaging, sensing and photoelectric detection.

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