Florescence Emission Research Articles

S-scheme3D/3D Bi0/BiOBr/P Doped g-C3 N4 with Oxygen Vacancies (Ov) for Photodegradation of Pharmaceuticals: In-situ H2O2 Production and Plasmon Induced Stability.

Complications accompanying photocatalyst stability and recombination of exciton charges in pollutants degradation has been addressed through the construction of heterojunctions, especially S-scheme heterojunction with strong and distinctive redox centres. Herein, an S-scheme BiOBr (BOR) and g-C3N4PO4 (CNPO) catalyst (BORCNPO) with oxygen vacancy (Ov) was synthesized for levofloxacin (LVX) and oxytetracycline (OTC) photodegradation under visible light. The 3D/3D BORCNPO catalyst possessed C-O-Br bridging bonds for efficient charge transfer during the fabrication of S-scheme heterojunction. In-situ H2O2 formation affirmed by potassium titanium (IV) oxalate spectrophotometric method improved the mineralization ability of BORCNPO7.5 catalyst. Bi0 surface plasmon resonance (SPR) enhanced formation and involvement of ⋅O2 - and the stability of the catalyst which increased reaction rate with increasing cycling experiments. XPS and radical trapping experiments supported the S-scheme charge transfer mechanism formation with high degradation rate of LVX which was 3 times higher than OTC degradation rate. Mineralization of pollutants and their intermediates were demonstrated with florescence excitation and emission matrix (FEEM) and quadruple time of flight high performance liquid chromatography (QTOF-HPLC). This work advances development of highly stable and efficient catalysts for photodegradation of pollutants through the formation of S-scheme heterostructure.

Biosynthesis of the phycocyanin β-subunit in Escherichia coli BL21 and its antioxidant activity and application in the preservation of fresh-cut apples

In this study, the biosynthesis of phycocyanin β-subunit (CpcB) in Escherichia coli BL21 was investigated, and its antioxidant activity and application in anti-browning of fresh-cut apples was explored. Four genes (cpcB, cpeS, hox1 and pcyA) involved in the biosynthesis of CpcB were cloned and transformed into E. coli BL21 by constructing recombinant plasmid pETDuet-5. The positive transformant was screened by ampicillin resistance. The analysis of SDS-PAGE and zinc fluorescence spectrum showed that CpcB was successfully expressed in E. coli BL21 with a molecular weight of 21 kDa. The purified CpcB had a maximum absorption peak at 615 nm, and its maximum florescence emission wavelength was 640 nm. It exhibited a stronger ability to scavenge four free radicals than Vc. The color change in fresh-cut apples was obviously delayed by the CpcB treatment. These results suggest that CpcB may be used as a potential anti-browning agent for food preservation.

Photophysical properties of novel tetra-3-substituted phthalocyanines of Zn(II), Cu(II) and Pd(II)

Newly metallo-phthalocyanines substituted MPc1 of zinc, copper, and palladium, bearing 3-((2,6-di(pyridin-3-yl)-phenoxy) substituent at [Formula: see text]-position (non-peripheral) were synthesized and characterized by common spectroscopic methods such as 1H-NMR, IR-FTR, MS, UV-Visible and florescence emission. Flowing several synthetic routes, the yield was increased in the series of metals: from CuPc1, PdPc1, to ZnPc1 and from ZnPc1, to ZnPc2, to ZnPc3, compared with their analogies in the literature. Afterwards, the effect of changing metals and substituents’ positions increased the Q-band value and florescence emission from PdPc1 to CuPc1 to ZnPc1 and from ZnPc2 ([Formula: see text]-position) to ZnPc3 (octa-position), to ZnPc1([Formula: see text]-position) and from cationic phthalocyanines ZnPc 2Me to ZnPc 3Me to ZnPc 1Me. The study of aggregation tendance in DMSO was examined in different concentrations to confirm that there was no aggregation appearance.

(Invited) Fluorescence and Sensing Applications of Graphene Oxides

First, the florescence emission mechanism of graphene oxide will be discussed. Second, fluorescence of graphene oxide can be tuned by tailoring functional groups. Third, graphene oxide-based sensors can be designed with graphene oxide either as an energy donor or as an energy acceptor. Fourth, graphene oxide-based sensors have been sued to detect heavy metal and biomarkers.

Aqueous CdTe colloidal quantum dots for bio-imaging of Artemia sp

Aqueous Cadmium Telluride (CdTe) colloidal quantum dots was synthesized using 3-mercaptoproponic acid (3-MPA) as a capping agent. CdTe QDs with band gap of 2.26 eV exhibit absorption edge and florescence emission at 502 nm and 569 nm respectively. The shoulder peak appearance in florescence emission owing to state filling effect. The cubic zinc-blend crystal structure of CdTe QDs are confirmed from XRD pattern with crystallite size ~2.12 nm. The morphological analysis carried out through HRTEM show spherical shaped particles with the average particles size of 3-MPA capped CdTe QDs is 3.3 nm. The elemental compositional and capping effect of the 3-MPA caped CdTe QDs are characterized via EDS, FTIR spectrum and Raman analysis. The bioimaging of Artemia sp using CdTe QDs is accomplished by way of dipping the Artemia animal into greenish-yellow colored (λemission 569) CdTe QDs aqueous solution. The fluorescent images showed clear morphology features of dead juvenile Artemia without affecting their internal and external structure. The linking of CdTe QDs to calcium localized in different cytoplasmic compartments of juvenile Artemia sp through MPA ligand lead to obtain the bright images. This study confirm that water soluble colloidal CdTe QDs well suitable for external morphological observation in a lower invertebrate like Artemia, Daphnia and Jellyfishes.

Amyloid-like Prep1 peptides exhibit reversible blue-green-red fluorescence in vitro and in living cells.

PREP1-based peptides form amyloid-like aggregates endowed with an intrinsic blue-green-red fluorescence with an unusual sharp maximum at 520 nm upon excitation with visible light under physiological conditions. The peptide PREP1[117-132], whose sequence does not contain aromatic residues, presents a pH-dependent and reversible fluorescence, in line with its structural transition from β-sheet rich aggregates to α-helix structures. These findings further demonstrate that the non-canonical fluorescence exhibited by amyloids is an articulated phenomenon.

Application of fluorescence spectroscopy coupled with PLSR for the estimation of quercetin in four medicinal plants

Abstract Quercetin, a member of a large family of polyphenolic compounds, has received remarkable attention due to its overwhelming presence in nutritional supplements. It is believed to have protective effects against several degenerative diseases by preventing lipid peroxidation. In the current study, the estimation of quercetin in methanol extracts of four medicinal plants including Amaranthus cruentus, Berberis calliobotrys, Solanum muricatum and Ribes himalense was made by our developed fluorescence spectroscopic method coupled with PLSR. The results obtained indicated that methanol extract of R. himalense exhibited higher quercetin content (3.83 ± 0.01%) followed by B. calliobotrys (1.91 ± 0.01%), A. eruentus (1.83 ± 0.02%) and S. muricatum (0.87 ± 0.05%). These results were also cross validated with UV–visible spectroscopy and found to be in close proximity to florescence emission method.

Development of inexpensive biosorbents from de-oiled mustard cake for effective removal of As(V) and Pb(II) ions from their aqueous solutions

This study aimed to develop inexpensive biosorbents from an agriculture waste material (mustard cake) for the effective removal of As(V) and Pb(II) ions from their aqueous solutions. The derived biosorbents were characterized by SEM, FT-IR, pXRD, zeta potential, surface area, pore size distribution and florescence emission spectroscopy (FES).The impact of the dose, adsorbate concentration, pH, time and temperature variation onto the biosorption were performed in batch type study. Various models were modeled; however, Langmuir model was found best representative in both the cases. Adsorption process of both As(V) and Pb(II) follows pseudo-second order kinetics with (R2=0.99). Intra-particle diffusion study implies that the thickness of the boundary layer effect is more in the case of Si-PAMC than C-PAMC. The biosorption mechanism is governed by complex interplay of inter ionic forces and complex formation ability of the metal ions in aqueous solution at a particular pH value. The FES study reveals the hydrophobic interactions. The desorption study revealed that the peak desorption from Si-PAMC was found as 53.73% for As(V) in 0.1M HCl and 62.52% for Pb(II) in 0.05M HCl solution whereas for C-PAMC it is found as 75.37% for As(V) and 80.35% for Pb(II) in 0.1M HCl solution of each metal ions, respectively. The comparative biosorption reveals that Si-PAMC has better biosorption than C-PAMC which is primarily attributed to the presence of mesoporous silica. The present study concludes that the mustard cake seems to have potential for effective removal of metal ions from industrial waste streams.

New Approach of Synthesizing Mineral Product from Industrial Waste

A new approach of using industrial waste to produce synthetic mineral product was studied in this paper. A synthetic mineral product which is precipitated calcium carbonate (PCC) was synthesized by using ionic sucrose solution method, whereby sucrose solution acts as promoter to increase the production of the PCC. Carbide lime, a waste from acetylene gas industry was used as starting material and first dissolved in the sucrose solution. The concentrations of the sucrose solution were varied from 5to 15 °Brix. The effect of the sucrose solution concentration was studied by using multiple characterization methods such as X-ray diffraction (XRD), X-Ray Florescence (XRF) and field emission scanning electron microscope (FESEM). The XRD and XRF results had proven that the synthesized PCC was calcium carbonate with > 98% purity. The morphologies of the PCC were observed by FESEM in which cubical shape was formed at 5 to 12 °Brix and grain shape at 13 to 15 °Brix. The distribution of the PCC particles was observed to be homogenous. The yield of the PCC increased as the Brix values increased.

Selective Determination of Trinitrotoluene Based on Energy Transfer between Carbon Dots and Gold Nanoparticles.

A fluorescence resonance energy transfer (FRET) system between carbon dots (C-dots) and amine-capped gold nanoparticles (AuNPs) was developed for the selective determination of 2,4,6-trinitrotoluene (TNT). C-dots have an intrinsic florescence emission depending on their exciting wavelength. In the presence of AuNPs, C-dots adsorb on the Au surfaces, and NPs treat as energy acceptor, which can receive light emitted by C-dots, leading to decrease the fluorescence intensity of C-dots. Furthermore, it is observed that nitroaromatic compounds, especially TNT, could restore this fluorescence due to selective interaction with AuNPs via amine groups, and so releasing the C-dots. Based on this effect, a sensitive and selective fluorescence turn-on probe was designed for the determination of TNT. Some important factors including AuNPs and C-dot concentrations and media pH, which would affect the efficiency of the probe, were optimized. Under the optimum experimental conditions, good linear relationships in the range of 7 - 250 nmol L(-1) TNT with the detection limit of 2.2 nmol L(-1) were obtained. The proposed method was satisfactorily applied to the determination of TNT in the environmental water samples. Compared with previous reports, the developed method has relatively high sensitivity, short analysis time, low cost and ease of operation.

Biphotonic holographic grating recordings for different polarization configurations in spirooxazine-doped polymers.

Spirooxazine-doped polymers exhibit a fast photochromism response and high polarization sensitivity after irradiation in the short-wavelength range. Based on such properties, holographic grating recordings accompanying a linearly polarized blue-violet beam (405nm) in a photochromic film were performed by two coherent green beams (532nm) for s-s, p-p, s-p left-to-right circular polarization and right-to-right circular polarization. Under the biphotonic action of 405 and 532nm, the temporal evolution of the diffraction efficiency was strongly dependent on the polarization configuration of the recording beams. It was found that the blue-violet irradiation plays a dual role in holographic recordings: generation of merocyanine aggregation and induction of anisotropy. The experimental results were precisely fitted with a phenomenological model, assuming the simultaneous formation of one absorption grating induced by the 532nm light and two coupling phase gratings generated from the refractive index changes by recording and auxiliary beams. The existence of absorption and phase gratings was proved by observing the florescence emission of holographic gratings and testing the dependence of the diffraction efficiency on the reading beam polarization state, respectively. The results provided a good deal of insight into the photochromic behavior of spirooxazine in polymers and created a new range of applications in the field of high-density optical storage.

EVA film doped with β-diketones macromolecular lanthanide complexes: Preparation, characterization and application

In this study, the β-diketones groups functionalized polymer D-HEA-C was first synthesized by chemically attaching D-HEA to the side chains of polycaprolactone and then coordinated with Eu(III) to form β-diketones macromolecular complexes. 1H NMR, FT-IR, GPC, ICP-AES, ultraviolet absorption and florescence emission were used to characterize the polymeric rare earth complex materials composed of D-HEA-C and Eu3+ ion. The synthesized β-diketones macromolecular complexes were doped into EVA film to test the energy conversion efficiency. TGA, Transmittance, UV absorption spectra, florescence emission and SEM were used to study the properties of the doped EVA film. The macromolecular complexes could not only limit the coordination of small molecules to effectively avoid the fluorescence quenching, but also enhance the fluorescence intensity of the complex. Moreover, the β-diketones macromolecular complexes have good compatibility with the EVA matrix, and could increase the photovoltaic conversion efficiency and service life of EVA film. Therefore, the β-diketones macromolecular complexes could act as efficient light conversion molecular devices, and have a broad prospect in the solar packaging film.

Three dimensional electro catalytic oxidation of aniline by boron doped mesoporous activated carbon

In this report, boron doped mesoporous activated carbon (B-MAC) was synthesized by direct hydrothermal route. The prepared B-MAC was characterized for HR-TEM, wide-angle XRD, SEM, XPS, FTIR and N2 sorption analyses. The results suggested that the B-MAC is mesoporous in structure and amorphous in nature, with surface area of 3.036m2g−1. The B-MAC was chosen as a catalyst for the electrochemical oxidation of synthetic aniline solution. For the oxidations process, graphite rod was chosen as anode; SS 316 was chosen as cathode in the electrochemical catalytic oxidation process. The electro chemical oxidation of aqueous aniline solution was confirmed through UV–visible spectroscopy, Florescence emission spectrum and cyclic voltammetry analyses. The results revealed that, the removal efficiency of COD and aniline by B-MAC was found to be 76–80% and 80–85%, respectively, in electro catalytic oxidation. MAC fluidized electro catalytic oxidation system removed COD by 40–45% and aniline by 50–62%, respectively. Thus, the B-MAC catalyst was found to be viable for the electrochemical treatment of aniline containing waste water.

Synthesis of Benzoic Acid Derivative-Bonded Polystyrene Ligand and Photoluminescence Properties of Its Complex with Eu(Ⅲ) Ion

The nucleophilic substitution reaction between the chloromethyl group of chloromethylated polystyrene(CMPS) and phenolic hydroxyl group of 3-nitro-4-hydroxy benzoic acid(NHBA) was conducted,and the nitro-benzoic acid(NBA) ligand was bonded on the side chains of polystyrene(PS) to yield nitro benzoic acid functionalization polystyrene PS-NBA.In this work,the nucleophilic substitution reaction between CMPS and NHBA was systematically investigated to optimize the reaction conditions.The coordination reaction between PS-NBA and Eu3 +ion was carried out to give polymer-rare earth complex,PS-(NBA) 3-Eu(Ⅲ).The chemical structure of PS-NBA was characterized by FTIR and1H NMR spectra and the florescence emission of PS-(NBA) 3-Eu(Ⅲ) was preliminarily examined.The results show that the nitro substitute group in benzene ring can reduce the rate of the substitution reaction.The stronger polarity solvents and higher reaction temperature(70 ℃) favor the substitution reaction.The ligand NBA on the side chain of the functionalized polymer PS-NBA can strongly sensitize the fluorescence-emission of Eu3 +ion,and its sensibilization is much stronger than that of benzoic acid(BA) ligand.The polymer-rare earth complex PS-(NBA) 3-Eu(Ⅲ) possesses much stronger fluorescence emission intensity than PS-(BA) 3-Eu(Ⅲ).

Glucose and fluoxetine induce fine structural change in human serum albumin.

Human serum albumin has been used as a model protein for protein folding and ligand binding studies over many decades. Due to its long life period and high concentration in plasma, HSA is highly sensitive to glycation. It is reported that 175 mg/dL glucose concentration is a threshold of kidney activity for the beginning of excretion of glucose. pH denaturation of HSA in absence and presence of different concentrations of glucose is studied and based on the Pace two-state model, the findings are analyzed. In addition, florescence emission data of albumin range in the period of 300-500 nm was depicted. The amounts of free energy change and [D]1/2 parameters of unfolding in correspond to florescence date indicate that glucose induces fine structural change in human serum albumin. Results showed that 175 mg/dL glucose concentration is a critical point for albumin structural and functional alteration.

Preparation of Aryl Carboxylic Acid-functionalized Polystyrene and Preliminary Exploration of Florescence Emission of Formed Polymer-Rare Earth(Tb(Ⅲ)) Complexes

Polystyrene(PS) was modified with 4-(chloromethyl) benzoic acid(CMBA) via Friedel-Crafts alkylation reaction,where benzoic acid(BA) ligand was bonded on the side chains of PS,yielding the functional macromolecule BAPS.The chemical structure of BAPS was characterized by FTIR,1H NMR and UV absorption spectra.The coordination reaction between BAPS and Eu3+ ion as well as the coordination reaction between BAPS and Tb3+ ion were carried out,resulting in the polymer/rare-earth complexes,BAPS-Tb(Ⅲ).The florescence emission of BAPS-Tb(Ⅲ) was preliminarily examined.In this work,the effects of the main factors on the Friedel-Crafts alkylation action between CMBA and PS were examined,the reaction mechanism was investigated,and the reaction conditions were optimized.The experimental results show that the Friedel-Crafts alkylation reaction between CMBA and PS can proceed successfully,and the suitable reaction conditions are as follows: a temperature of 70 ℃,with N,N-dimethylacetylamide(DMAC) as solvent,and SnCl4 as Lewis catalyst.The polymer/rare-earth complex BAPS-Tb(Ⅲ),possesses the fluorescence-emission spectrum of Tb3+ ion.More significantly,the macromolecular ligand BAPS can strongly sensitize the fluorescence-emission of Tb3+ ion.

Preparation of aromatic carboxylic acid-functionalized polysulfone and preliminary exploration of florescence emission character of formed polymer-rare earth complexes

Polysulfone (PSF) was modified via a polymer reaction, Friedel–Crafts alkylation of PSF with 4-(chloromethyl) benzoic acid (CMBA) as reaction reagent, and benzoic acid (BA) ligand was bonded onto the side chains of PSF, resulting in the aromatic carboxylic acid-functionalized PSF, BAPSF. The chemical structure of BAPSF was characterized by FTIR, 1H NMR and UV/vis absorption spectrum. BAPSF was allowed to coordinate to Eu(III) and Tb(III) ions, respectively, and two luminescent polymer-rare earth complexes, BAPSF-Eu(III) and BAPSF-Tb(III) were prepared. The fluorescence emission character of the two complexes was preliminarily explored. The functionalization modification process of PSF and the reaction mechanism were emphatically investigated. The experimental results show that the Friedel–Crafts alkylation reaction between PSF and CMBA can be carried out smoothly. The two polymer-rare earth complexes, BAPSF-Eu(III) and BAPSF-Tb(III), exhibit the characteristic fluorescence emissions of Eu3+ and Tb3+ ions, respectively. More importantly, BAPSF can powerfully sensitize the fluorescence emissions of Eu3+ and Tb3+ ions, and the effective energy transfer indeed take places from the macromolecular ligand BAPSF to the coordinated Re3+ and Tb3+ ions.

Protegrin-1 Inhibits Dengue NS2B-NS3 Serine Protease and Viral Replication in MK2 Cells

Dengue diseases have an economic as well as social burden worldwide. In this study, the antiviral activity of protegrin-1 (PG-1, RGGRLCYCRRRFCVCVGR) peptide towards dengue NS2B-NS3pro and viral replication in Rhesus monkey kidney (MK2) cells was investigated. The peptide PG-1 was synthesized by solid-phase peptide synthesis, and disulphide bonds formation followed by peptide purification was confirmed by LC-MS and RPHPLC. Dengue NS2B-NS3pro was produced as a single-chain recombinant protein in E. coli. The NS2B-NS3pro assay was carried out by measuring the florescence emission of catalyzed substrate. Real-time PCR was used to evaluate the inhibition potential of PG-1 towards dengue serotype-2 (DENV-2) replication in MK2 cells. The results showed that PG-1 inhibited dengue NS2B-NS3pro at IC50 of 11.7 μM. The graded concentrations of PG-1 at nontoxic range were able to reduce viral replication significantly (P < 0.001) at 24, 48, and 72 hrs after viral infection. However, the percentage of inhibition was significantly (P < 0.01) higher at 24 hrs compared to 48 and 72 hrs. These data show promising therapeutic potential of PG-1 against dengue infection, hence it warrants further analysis and improvement of the peptide features as a prospective starting point for consideration in designing attractive dengue virus inhibitors.

Structure and Florescence Emission Properties of a Polymer-Rare Earth Complex Composed of Aryl Carboxylic Acid-Functionalized Polysulfone and Tb(III)

通过大分子反应将苯甲酸（BA）键合在聚砜（PSF）侧链,制得芳羧酸功能化的聚砜（PSFBA）.以PSFBA为大分子配基,以邻菲啰啉（Phen）为小分子配体,与Tb（Ⅲ）配位,分别制备了二元配合物PSFBA-Tb（Ⅲ）与三元配合物PSFBA-Tb（Ⅲ）-Phen,采用傅里叶变换红外（FTIR）光谱和紫外（UV）吸收光谱对配合物进行了表征,深入研究了配合物（溶液与薄膜）的荧光发射性能及热稳定性与结构的关系.研究结果表明,以PSFBA为大分子配基所形成的高分子-稀土配合物,均能发射出很强的Tb（Ⅲ）特征荧光,即键合在PSFBA侧链的配基BA能有效地敏化Tb（Ⅲ）的荧光发射.二元配合物PSFBA-Tb（Ⅲ）的表观饱和配位数为10,即当二元配合物具有PSF-（BA）5-Tb（Ⅲ）的结构时,BA对Tb（Ⅲ）的配位表观上达到饱和,此时二元配合物具有最强的荧光发射.按n（Phen）：n（Tb（Ⅲ））=1的比例将Phen加入二元配合物PSF-（BA）5-Tb（Ⅲ）溶液中进行补充配位,所制备的三元配合物PSF-（BA）5-Tb（Ⅲ）-（Phen）1与惯用比例的三元配合物PSF-（BA）1-Tb（Ⅲ）-（Phen）3或PSF-（BA）1-Tb（Ⅲ）-（Phen）2相比,不仅荧光发射强度高,而且热稳定性能好,是一种高性能的场致发光材料.

Structural and biochemical study on the inhibitory activity of derivatives of 5-nitro-furan-2-carboxylic acid for RNase H function of HIV-1 reverse transcriptase

Rapid emergence of drug-resistant variants is one of the most serious problems in chemotherapy for HIV-1 infectious diseases. Inhibitors acting on a target not addressed by approved drugs are of great importance to suppress drug-resistant viruses. HIV-1 reverse transcriptase has two enzymatic functions, DNA polymerase and RNase H activities. The RNase H activity is an attractive target for a new class of antiviral drugs. On the basis of the hit chemicals found in our previous screening with 20,000 small molecular-weight compounds, we synthesized derivatives of 5-nitro-furan-2-carboxylic acid. Inhibition of RNase H enzymatic activity was measured in a biochemical assay with real-time monitoring of florescence emission from the digested RNA substrate. Several derivatives showed higher inhibitory activities that those of the hit chemicals. Modulation of the 5-nitro-furan-2-carboxylic moiety resulted in a drastic decrease in inhibitory potency. In contrast, many derivatives with modulation of other parts retained inhibitory activities to varying degrees. These findings suggest the binding mode of active derivatives, in which three oxygen atoms aligned in a straight form at the nitro-furan moiety are coordinated to two divalent metal ions located at RNase H reaction site. Hence, the nitro-furan-carboxylic moiety is one of the critical scaffolds for RNase H inhibition. Of note, the RNase H inhibitory potency of a derivative was improved by 18-fold compared with that of the original hit compound, and no significant cytotoxicity was observed for most of the derivatives showing inhibitory activity. Since there is still much room for modification of the compounds at the part opposite the nitro-furan moiety, further chemical conversion will lead to improvement of compound potency and specificity.