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Fluorescence Imaging for Ultrafiltration of Individual Nanoparticles from a Colloidal Solution in Track Membranes
摘要： We have used ? uorescence nanoscopy for direct imaging of adsorption of individual colloidal quantum dots of diameter ~10 nm (spherical core/shell CdSeS/ZnS semiconductor nanocrystals, functionalized by organic oleic acid ligands) in nanopores of a nuclear ? lter (a polypropylene track membrane with pores of diameter ~500 nm). We have shown that when a colloidal toluene solution passes through the pores of the membrane, the nanoparticles are completely retained at a depth of 10 μm.
关键词： nanopore,single-photon source,CdSe,membrane,nanoscopy,entangled-photon source,quantum dot,colloidal solution,microscopy,nanoparticles,ultra? ltration,oleic acid,nuclear ? lter,luminescence,polymer
更新于2025-09-23 15:21:21
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Validation of spectrophotometric determination of chlorogenic acid in fermentation broth and fruits
摘要： A fast and accurate ultraviolet-visible (UV-vis) spectrophotometric method was established to determine the presence of chlorogenic acid (CGA) according to potassium ferricyanide-Fe (III) detection system. The reaction temperature and pH level greatly influenced the CGA absorption spectrum. Maximum UV-vis absorption wavelength occurred at 790 nm under the optimum conditions (at 25 ℃ and pH 7.0). The results of UV-vis were further assessed by comparing the results with those of high-performance liquid chromatography (HPLC). The proposed method showed a wide linear sensing range of 10.0-800.0 μg mL-1 (R2 = 0.9996) and a high degree of precision (%R.S.D. < 1.50) and recovery (%R.S.D. > 3.39). Results of CGA and HPLC methods correlated well with each other. The proposed accurate, rapid, sensitive, low-cost, and high-throughput method was successfully used to quantify CGA in fermentation broth and fruits (Mango). Therefore, it may be applied for measuring CGA in biological samples.
关键词： Ultraviolet-visible spectrum,Chlorogenic acid,biological samples,high-throughput,HPLC
更新于2025-09-23 15:21:21
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Isostructural series of [{Al(H2O)6}{Ln(pda)3}].10H2O: Synthesis, Structure and Photoluminescence
摘要： A new series of six isostructural molecular solids of the composition [{Al(H2O)6}{Ln(pda)3}].10H2O where Ln = Sm, Eu, Gd, Tb, Dy and Yb have been synthesized and structurally characterised. All the solids are built of three major building blocks: the lanthanide dipicolinate anion, {Ln(pda)3}3-, the counter cation, {Al(H2O)6}3+ and a hexameric water cluster in chair form. The cations and the anions supramolecularly aggregate forming a 2D H-bonded sheet; the sheets are further stabilised through hexameric water clusters in chair form and water molecules. The crystals containing Sm, Eu, Tb and Dy showed characteristic emission of lanthanide ions.
关键词： 2,Lanthanide,6-dipicolinic acid,Photoluminescence.
更新于2025-09-23 15:21:21
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Detection and monitoring of in vitro formation of salicylic acid from aspirin using fluorescence spectroscopic technique and DFT calculations
摘要： Acetylsalicylic acid commonly termed as aspirin (AS) is a well known antipyretic and anti-inflammatory drug which can also be used to reduce death risks due to heart attack. In addition to this, it also exhibits some adverse effect such as gastrointestinal, tinnitus, Reye’s syndrome. The side effects of AS such as gastrointestinal ulcer, tinnitus and Reye’s syndrome are caused due to conversion of AS into its active metabolite salicylic acid (SAL). Conversion of AS into SAL has been investigated generally at basic pH. Since the pH of Gastrointestinal tract is on average neutral ranging from 6.5-7.4. Therefore in the present research work, in vitro conversion of AS to SAL was detected at neutral pH in both aqueous medium and human blood serum samples by time series fluorescence measurements and DFT study. The SAL obtained from AS at neutral pH was observed to be stable for ~ 6 and ~ 4 days in aqueous medium and blood serum, respectively. The mechanism of conversion of AS into SAL was investigated using the transition state theory employing density functional theory (DFT). On the basis of DFT calculation the in vitro formation of SAL from AS at neutral pH was found to involve two intermediate transition states.
关键词： Fluorescence,Rate Constant,Transition State,Salicylic acid,Aspirin
更新于2025-09-23 15:21:21
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Non-oxidation reduction strategy for highly selective detection of ascorbic acid with dual-ratio fluorescence and colorimetric signals
摘要： Ascorbic acid (AA), one of the most important vitamins, acts a critical role in various physiological reactions and is involved in many diseases. Thus, the development of highly selectivity methods for detecting AA level with the presence of different reducing substances is of great significance in complicated serum matrix. In this paper, a non-oxidation reduction regulation (NRR) strategy was designed to construct a novel dual-ratio fluorescence and colorimetric dual-readout assay for highly selective detection of AA. The strategy involves three processes: Ag+ oxidated o-phenylenediamine (OPD) to 2,3-diaminophenazine (OPDox), AA inhibited the generation of OPDox and the AA was oxidized to dehydroascorbic acid (DHAA). The specific performance of DHAA NRR, due to the condensation reaction between dicarbonyl group of DHAA and diamine group of OPD, that is confirmed by ESI-MS and 1H NMR spectra analysis, can remarkably enhance the selectivity of AA detection. Additionally, the proposed method based on NRR strategy not only provides a sensing platform for probing AA but also shows promising outlook in biomedical studies.
关键词： O-phenylenediamine,Non-oxidation reduction regulation,Ascorbic acid,Dual-ratio,Dual-readout
更新于2025-09-23 15:21:21
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Selective and Sensitive Sensing of Hydrogen Peroxide by a Boronic Acid Functionalized Metal–Organic Framework and Its Application in Live-Cell Imaging
摘要： A new boronic acid functionalized Zr(IV) metal?organic framework having the capability of sensing H2O2 in live cells is reported. The Zr-MOF bears a UiO-66 structure and contains 2-boronobenzene-1,4-dicarboxylic acid (BDC-B(OH)2) as a framework linker. The activated Zr-UiO-66-B(OH)2 compound (called 1′) is highly selective for the ?uorogenic detection of H2O2 in HEPES bu?er at pH 7.4, even in the presence of interfering ROS (ROS = reactive oxygen species) and other biologically relevant analytes. The ?uorescent probe was found to display extraordinary sensitivity for H2O2 (detection limit 0.015 μM) in HEPES bu?er, which represents a lower value in comparison to those of the MOF probes documented so far for sensing H2O2 using other analytical methods. Taking advantage of its high selectivity and sensitivity for H2O2 in HEPES bu?er, the probe was successfully employed for the imaging of intracellular H2O2. Imaging studies with MDAMB-231 cells revealed the emergence of bright blue ?uorescence after loading with probe 1′ and subsequent treatment with H2O2 solution.
关键词： Zr(IV) metal?organic framework,boronic acid,live-cell imaging,fluorescent probe,H2O2 sensing
更新于2025-09-23 15:21:21
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Design, Synthesis and Photophysical Analysis of New Unsymmetrical Carbazole-Based Dyes for Dye-Sensitized Solar Cells
摘要： The molecular design, synthesis, and characterization of di-anchoring carbazole-based dyes (Car-Cy, Car-Amin, and Car-Mal) with A-π-D-π-A-π-A structure as materials for dye-sensitized solar cells applications (DSSCs) are reported. The electron-rich carbazole moiety in the structure of synthesized dyes is connected with acceptor/ or anchoring groups (cyanoacetic acid, 4-aminobenzoic acid, and malonic acid) and π-spacers (vinylene and cynovinyl thiophene). Electronic characteristics and molecular geometry of the sensitizers were optimized using Density Functional Theory (DFT), and the influence of dye structure on their photovoltaic performances was studied. Among the synthesized dyes in this research, Car-Amin dye presents a better photovoltaic performance as a sensitizer in the constructed device, with a power conversion efficiency (PCE) of 2.27%, JSC of 5.95 mAcm?2, VOC of 0.54 V and FF of 71%. The enhanced performance of this dye could be related to the powerful electron-withdrawing characteristic of the 4-aminobenzoic acid as an acceptor group in the dye structure. Consequently, the impact of various acceptor groups on the constructed DSSC devices was examined, and the results indicated that the improvement of DSSC performance is due to the presence of 4-aminobenzoic acid as acceptor on the carbazole-based dyes.
关键词： 4-aminobenzoic acid,Malonic acid,Dye-sensitized solar cell (DSSC),Carbazole,Cyanoacetic acid
更新于2025-09-23 15:21:01
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Synthesis of eight isostructural 2D lanthanide coordination polymers assembled by rigid furan-2,5-dicarboxylic acid and flexible adipic acid as linkers and exploration of luminescent Eu/Tb polymers as efficient and sensitive sensors for nitroaromatic compounds
摘要： Detection of hazardous chemicals is crucial for a healthy and safe environment as well as for the well-being of humans. A confluence of chemistry and engineering continues to improve the sensitivity and selectivity for several classes of harmful chemicals with the promise of cheap and portable sensing. Herein, following the function-oriented research strategy, eight novel lanthanide coordination polymers (Ln-CPs) have been successfully assembled with the framework composition [Ln(2,5-FDC)0.5(Adip)(H2O)2] (Ln = Nd (1), Sm (2), Eu (3), Gd (4), Tb (5), Dy (6), Ho (7), Er (8), 2,5-FDC2? = furan-2,5-dicarboxylate, Adip2? = Adipate) under solvothermal synthesis conditions. The structural analysis indicates that all the eight CPs have the same structural features. All compounds crystallize in the orthorhombic crystal system (space group Pnma) with point symbol {33·44·53} and consist of 2D cem topological type. The linkers 2,5-FDC2? and Adip2? exhibit μ2-κ4,Z1:Z1:Z1:Z1 and μ3-κ5,Z2:Z1:Z1:Z1 coordination modes respectively. The as-synthesized polymers were characterized by powder X-ray crystallography, infrared spectroscopy, thermogravimetric analysis, and photoluminescence studies. CP-3 and CP-5 are promising luminescent lanthanide coordination polymers (Ln-CPs) and function as efficient sensors for the detection of nitroaromatic compounds at the ppm level in mix N,N′-dimethyl formamide-aqueous medium via the luminescence quenching mechanism.
关键词： furan-2,5-dicarboxylic acid,lanthanide coordination polymers,adipic acid,luminescent sensors,nitroaromatic compounds
更新于2025-09-23 15:21:01
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Design, Synthesis and Application of Imidazole-Based Organic Dyes in Dye Sensitized Solar Cells
摘要： Metal-free D–D–p–A type dyes (i.e., Car-Cy, Car-Rh, Dpa-Cy, and Dpa-Rh) were designed and synthesized for dye-sensitized solar cells (DSSCs). In the structure of the sensitized dyes, an imidazole ring is connected to a carbazole or diphenylamine moiety as a donor while cyanoacetic acid or rhodanine-3-acetic acid was introduced as an acceptor/anchor. The molecular structures of D–D–p–A type dyes were characterized using IR, NMR and MS spectral data. The optical, electrochemical, theoretical, light harvesting property, HOMO/LUMO levels, redox behavior, and photovoltaic properties of the synthesized dyes were evaluated. Among the fabricated photovoltaic devices based on the prepared dye, Dpa-Cy dye containing diphenylamine as a donor and cyanoacetic acid as an acceptor exhibited a high-power conversion efficiency of 1.70% with a short-circuit current density (JSC) of 4.48 mA cm?2, an open-circuit photovoltage (VOC) of 0.53 V and a fill factor of 72% under AM1.5 illumination (85 mW cm?2) in comparison with other dyes. Plane-wave calculations indicate that the dye binds reasonably strongly to the TiO2 surface, and the generated DOS picture shows an overlap of the molecular orbitals of the dye and the TiO2 bands. We conclude that the dyes have a promising role as sensitizers in DSSCs.
关键词： rhodanine-3-acetic acid,cyanoacetic acid,carbazole,DSSCs,diphenylamine
更新于2025-09-23 15:21:01
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Monitoring of Microwave-Assisted Acid-Catalyzed Transesterification for Biodiesel Production Using FT-NIR Spectroscopy with Continuous-Flow Cell
摘要： The homogeneous microwave-assisted sulfuric acid-catalyzed transesterification of soybean oil, waste Brazil nut oil, sunflower oil and chicken fat for ethylic and methylic biodiesel production is described herein. The experiments were carried out in pilot-scale multimode reactors. The effects of the alcohol to oil molar ratio, catalyst concentration and irradiation time on the conversion to biodiesel were investigated. The transesterification reactions were performed at relatively small alcohol to oil molar ratios (9:1, 8:1 and 6:1) affording near 100% of conversion in reaction times of 60 to 120 min. Partial least squares (PLS) regression analysis using FT-NIR spectroscopy was performed to monitor the progress of the acid-catalyzed methanolysis of soybean oil. The NIR spectra were collected during the transesterification reaction with a spectrophotometric continuous-flow cell. 1H NMR spectroscopy was employed to determine the conversion percentage and used as a reference to build the PLS calibration model employing NIR spectroscopy data.
关键词： vegetable oils,sulfuric acid,FT-NIR spectroscopy,Animal fat,homogeneous acid catalysis,microwave-induced transesterification
更新于2025-09-23 15:21:01