cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.14304038
title: Gold Nanoparticle/Tetrapyridylporphyrin Hybrid Material: Spectroscopic and Electrocatalytic Properties and Sensor Application

description: An electrocatalytic active hybrid material prepared by successive stepwise coordinative deposition of 20 nm diameter gold nanoparticles (AuNP) with 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphine (TPyP) on fluorine-doped tin oxide (FTO) substrates previously modified with 3-mercaptopropylsilane is described. Their interaction and assembly were studied by UV-Vis spectroscopy and surface enhanced Raman spectroscopy to understand the kinetics as well as the conformation on the porphyrin macrocycle on the electrode surface as a function of its concentration. The hybrid nanomaterial was a build-up in reproducible successive deposition steps as confirmed by the linear rise of the absorption bands assigned to AuNP and TPyP as a function of the number of AuNP/porphyrin hybrid deposition steps, as supported by scanning electron microscopy (SEM) images. Electrodes modified with the hybrid nanomaterials were prepared and characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), as well as their electrocatalytic properties for the oxidation of nitrite and sulfite investigated. FTO electrodes modified with the AuNP/TPyP hybrid showed remarkable electrocatalytic activity as confirmed by reproducible and sensitive amperometric responses for sensing nitrite and sulfite in comparison to the bare electrode while reducing overpotentials respectively to 0.8 and 0.4 V and improving the dynamic range (linear response allowing quantification in the 50 to 500 µmol L-1 range) for detection of analytes.
DOI: 10.6084/m9.figshare.14304036
title: Design, Synthesis, and Application of Colored Cobalt Pigments (Pink, Blue, Green)

description: The combination of white or colorless oxides (MgO, Al2O3, ZnO) with colorant ions (Co2+) generates colored pigments (pink, blue, green). The color is caused by the insertion of the colorant ion in the respective crystal lattices (periclase, alumina, wurtzite), as verified by X-ray diffraction. Absorption spectra in the visible region show analogous triplet behavior of the absorption bands for the doped alumina and wurtzite samples but a difference in tetrahedral distortion, which generates blue and green pigments. In contrast, cobalt-doped periclase has color-related parameters related to the pink color. Crystallite and particle sizes show nanometric dimensions in the range of 20-60 nm (magnesium), 20-180 nm (aluminum), and 40-220 nm (zinc). The color is related to the shape (crystalline phase), size, and presence of chromophore ions with absorption in the visible region. Colorimetric studies (CIE L*a*b*) show variations between colors as a function of the polysaccharide that is used (starch or pectin) as fuel. The color variation is subtle in some cases but is significantly noticeable in other cases. Commercial colorless ink dispersion (10% m/m) shows excellent compatibility with the maintenance of hues and a slight increase in color saturation (C*).
DOI: 10.6084/m9.figshare.14304033
title: Performance of Water Oxidation by 3D Printed Electrodes Modified by Prussian Blue Analogues

description: The water oxidation is the limiting step in the water-splitting process. Given this scenario, the development of new catalysts is essential in this field. The emergent demand is the use of Earth-abundant elements and catalysts with high performance under mild conditions. Because of this, catalysts such as Prussian Blue analogues (PBA) have been receiving a lot of attention in recent years. In addition, working under neutral conditions allows us to take advantage of the modification of conductive polymeric 3D printed electrodes (3DPE) with Prussian Blue. Thus, we described in this work the development of the polymeric 3D printed electrodes modified by cobalt-Prussian Blue and their performance in the water oxidation process. The 3D printed electrodes modified with Co3[Co(CN)6]2 (Co-Co PBA) have a Tafel slope of 343 mV dec−1 while those modified with Co3[Fe(CN)6]2 (Co-Fe PBA) have a Tafel slope of 378 mV dec−1. This means that both catalysts have the same mechanism for the water oxidation process. On the other hand, the overpotential of Co-Co PBA in 3DPE is lower than the value observed by Co-Fe PBA in 3DPE suggesting the best electrocatalytic activity for Co-Co PBA catalyst.
DOI: 10.6084/m9.figshare.14304032
title: Synthesis, Characterization, Spectroelectrochemical, Photophysical and HSA-Binding Properties of Novel and Versatile meso-Tetra(4-pyridylvinylphenyl)porphyrins Coordinated to Ruthenium(II)-Polypyridyl Derivatives

description: The free-base meso-tetra(4-pyridylvinylphenyl)porphyrin (1a) and its zinc(II) complex were synthesized and then functionalized with [Ru(bpy)2Cl]+ units (2a and 2b) via conventional methods and evaluated in terms of photophysical, electrochemical and biological aspects. All porphyrins present moderate singlet oxygen production and fluorescence quantum yield, and did not show any aggregation process. The photo-oxidation ability of those porphyrins decreased in the order 2b &gt; 1a &gt; 2a. The electrochemical behavior of 2a and 2b modified electrodes was evaluated by electroanalytical methods. Also the 2b electrode showed a smaller charge transfer resistance (36.70 Ω) when compared to 2a electrode (45.17 Ω). In addition, even after 30 consecutive injections of nitrite solution (1.0 × 10−4 mol L−1) using the flow injection analysis (FIA) system, the modified 2b electrode showed an relative standard deviation (RSD, n = 30) of 1.36% exhibiting a great potential as amperometric sensor for nitrite. Moreover, the biological evaluation towards human serum albumin (HSA) indicated spontaneous, weak and ground-state association in the IB subdomain (site III) and possibily a second site, changing the conventional interaction mode of porphyrins with biomolecules as consequence of the longer arms (porphyrin ring substituents at meso-positions) ending with a ruthenium polypyridyl complex, that may enhance the photodynamic therapy (PDT) efficiency of photogenerated reactive oxygen species (ROS) species.
DOI: 10.26300/15yf-tx16
title: MATLAB script to enhance, segment and vectorize 3D OCT microangiograms
DOI: 10.6084/m9.figshare.14304027
title: Effect of Push-Pull Ruthenium Complex Adsorption Conformation on the Performance of Dye Sensitized Solar Cells

description: A new series of tris-(bipyridyl)ruthenium-like complexes based on the 4-tripheylamine-2,2’:6’,2’’-terpyridine (TPA) push-pull ligand was prepared by incorporation of 4-carboxypyridine (cpy), 4,4’-dicarboxi-2,2’-bipyridine (dcbpy) and 4-carboxyterpyridine ligands (ctpy) ligands, in order to adsorb them on TiO2 in different anchoring conformations. The electron photoinjection and electron recombination processes of the respective dye-sensitized solar cells were greatly influenced by the molecular structure, which defined the surface concentration and surface charge on TiO2, such that the photoconversion efficiency was 10 times larger for [Ru(py)(dcbpy)(TPAtpy)] than for the [Ru(cpy)(bpy)(TPAtpy)](PF6) dye. Molecules anchoring in a more upright position and by a larger number of sites were shown to enhance the electron injection into TiO2 conduction band (CB) improving the short-circuit current (JSC), open circuit voltage (Voc) and the overall photoconversion efficiency. However, a positive net charge in the dye increased the back electron-transfer reactions and induced a decrease in both Voc and conversion efficiency.
DOI: 10.6084/m9.figshare.14304026
title: Preparation of Fluorescent Carbon-Based Dots from Waste Tire Pyrolysis

description: The pyrolysis of waste tire has been proposed as an alternative route to its recycling producing residual oils that can be used as fuels. In this work, a physicochemical process to obtain carbon-based dots (CBD) from carbon black (CBL) derivatives of tires is described. For this, the CBL was treated with different acids to produce CBL1 and CBL2 particles suspension. The pH of the suspension was adjusted to 5.6 to precipitate remaining impurities. Afterwards, the supernatant was ultra-centrifuged and the yellow pale solid, the purified CBD obtained by roto evaporation, was characterized by ultraviolet-visible spectrophotometer (UV-Vis), photoluminescence (PL) at 320-380 nm, high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared microscopy (mFTIR), and X-ray photoelectron spectroscopy (XPS). This material showed the typical excitation wavelength dependent emission and a PL quantum yield of 19.29% and was constituted by a well-defined spherical shaped and single sheets of “graphene quantum dots” with undefined shape, with potential applications in optoelectronic and fluorescence imaging devices.
DOI: 10.6084/m9.figshare.14304024
title: Improvements in Methyl-Bambus[6]uril Synthesis Yield

description: Bambus[n]uril synthesis may be challenging, and it is frequently achieved with low purity and low yields. We have studied the effect of different anions on the synthesis of bambus[6]uril, especially in terms of yield, exploring template effects driven by anions in the reaction medium. The influence of the anions is evident on such syntheses and ClO4− particularly led to unprecedented synthesis yields. Computational calculations have also been used to elucidate the influence of anions on cyclization process.
DOI: 10.6084/m9.figshare.14304023
title: Intercalation of Apocarotenoids from Annatto (Bixa orellana L.) into Layered Double Hydroxides

description: Synthetic conditions were evaluated to intercalate norbixin into layered double hydroxides (LDH). Norbixin was isolated from a hydrosoluble commercial annatto extract. LDH samples comprising M2+/Al3+ (M = Mg, Zn) were synthesized by coprecipitation and characterized by X-ray diffraction, thermal analysis coupled to mass spectrometry, vibrational spectroscopies, and solid-state 13C nuclear magnetic resonance. Radical scavenging activity of LDH hybrids was monitored by electron paramagnetic resonance towards the stable radical DPPH (1,1-diphenyl-2-picrylhydrazyl). LDH hosts presented more than 50 wt.% of norbixin and d-spacing (003) values of about 2.5 or 3.0 nm depending of the cation LDH composition. Vibrational spectra assignment (supported by density functional theory calculations) confirmed the chemical integrity of norbixin after intercalation into LDH. The inorganic layers were found to enhance the thermal stability of norbixin upon intercalation. The free radical scavenging capacity of norbixin was retained when immobilized into LDH. Considering that zinc and magnesium-LDH matrices are biocompatible and that norbixin presents biological activity, the hybrid materials appear as promising systems for biomedical assessment.
DOI: 10.6084/m9.figshare.14304021
title: Determination of Bisphenol A in Paper Products by Synchronous Fluorescence Spectoscopy and Estimation of Daily Exposure

description: In this study, a simple and fast procedure was developed and validated for the determination of bisphenol A (BPA) in paper products using synchronous fluorescence spectroscopy. The method was used for the determination of BPA in thirteen types of paper products, including thermal receipt papers, lottery tickets, bus tickets, business cards, mailing envelopes, flyers, napkins, printing paper, food contact paper, kitchen rolls, toilet paper, newspapers, and magazines. BPA was found in 98% of thermal receipt papers (n = 341) at concentrations ranging from below the limit of quantification (LOQ) to 27.7 mg g−1 with a geometric mean of 14.6 mg g−1 and a median of 17.7 mg g−1. The detection rate for other paper products was 96%, with BPA concentrations ranging from below the LOQ to 379 µg g−1 and a median of 17.3 µg g−1. The estimated daily intake for the adjusted bodyweight of BPA (calculated at median concentrations) through dermal absorption from handling papers was 14.5 and 1070 ng day−1 for the general population and occupationally-exposed individuals, respectively. The proposed analytical method is simple, fast, and cost-effective for the determination of BPA in paper samples. Moreover, an estimated daily exposure of Brazilians to BPA through dermal absorption from handling different types of papers is shown.
DOI: 10.6084/m9.figshare.14304018
title: Hybrid Hydrogels Based on Polyethylene Glycol Bioconjugated with Silylated-Amyloidogenic Peptides

description: Hybrid-peptide hydrogel arrangements are a promising alternative to obtaining biocompatible structures at the nanoscopic scale. In this work, a new class of hybrid hydrogels was obtained through the sol-gel process based on the reaction between an amyloid-like octapeptide sequence [RF]4 (where R = arginine and F = phenylalanine) covalently bonded with glycine-linked alkoxysilanes, and hybrid silylated polyethylene glycol (PEG). 1H nuclear magnetic resonance (NMR), liquid chromatography-mass spectrometry (LC-MS), and Fourier transform infrared spectroscopy (FTIR) analyses were used, resulting in synthesized precursor/intermediate molecules. The structure of hybrid hydrogel fibers was studied by atomic force microscopy (AFM) and small-angle X-ray scattering (SAXS), where the existence of two regions in the Guinier plot was observed, one being predominantly formed by polymer while the other one by peptide chains. The rheological measurements showed that viscoelastic parameters depend on both the amount of silane peptide in the hydrogel matrix and increased temperature. Also, the FTIR spectra indicated the coexistence of antiparallel and parallel β-sheet structure patterns into amyloid fibril hydrogels, which can be modulated by peptide-silane coupling in each formulation. The analyzed hydrogels showed thixotropic and shear-thinning rheology at physiological pH, leaving open the opportunity to topical drug delivery system applications in the future.
DOI: 10.6084/m9.figshare.14304015
title: Exploring Polypyrrole as Extraction Phase for Disposable Pipette Extraction Method for Multiclass Organic Micro-Pollutant Determination in River and Tap Water Using Gas Chromatography-Mass Spectrometry

description: The use of a polypyrrole (PPy) is described as an efficient extraction phase for disposable pipette extraction (DPX), in a fast and ruggedized analytical method for simultaneous determination of 18 organic micro-pollutants in water using gas chromatography-mass spectrometry (GC-MS). The DPX-blank pipettes were filled with PPy, a material produced through the chemical polymerization of PPy using iron(III) chloride hexahydrate. The optimized conditions were 5 extraction cycles with 600 µL of sample, adjusted to pH 9, and desorption with 150 µL of ethyl acetate using 7 cycles with the same aliquot. The calibration curves resulted in determination coefficient (R2) higher than 0.9963, the limit of detection (LOD) ranged from 0.4 to 1.5 µg L−1, and the limit of quantification (LOQ) were from 1.4 to 5.0 µg L−1. Excellent results were obtained for repeatability (2.3 to 15%, for 5 µg L−1) and intermediate precision, varying the day of analyses (3.9 to 15.5%) and the pipette tip (3.4 to 22.4%). The analyte recovery ranged from 75.4 to 115.0% for river water, and from 74.9 to 116.2% for tap water, in three different levels of concentration. The DPX-GC-MS method with PPy was successfully applied to determine the 18 analytes in river and tap water from the cities of Joinville and Florianópolis, Santa Catarina, Brazil.
DOI: 10.6084/m9.figshare.14304012
title: Pueraria lobata Root Constituents as Xanthine Oxidase Inhibitors and Protective Agents against Oxidative Stress Induced in GES-1 Cells

description: Ultrafiltration coupled with liquid chromatography-mass spectrometry (LC-MS) was established to screen xanthine oxidase (XO) inhibitors from Pueraria lobata root extract. Four compounds were screened out and identified as puerarin, daidzin, daidzein and genistein with half-maximal inhibitory concentration (IC50) values of 30.8, 5.31, 14.5 and 3.02 µg mL−1 on XO, respectively. The interactions between these compounds and XO were investigated by fluorescence spectroscopic method. The hydrogen peroxide induced oxidative stress model of human normal gastric epithelial cell lines (GES-1) was used to investigate the protections on injured cell. As a result, four XO inhibitors exhibited protective effects without cytotoxicity. With the increased concentrations of four inhibitors, cell viability was higher with decreased mortality rate, the decrease of superoxide dismutase activity, leakage of lactate dehydrogenase and increase of intracellular superoxide anion production induced by hydrogen peroxide were restrained. It showed that these four XO inhibitors could effectively enhance cell viability and protect injury of GES-1 cells from oxidative stress.
DOI: 10.6084/m9.figshare.14304010
title: A Simple Approach to Analyze Sugar Nectar Composition in Flowers Using Capillary Electrophoresis and Enzymatic Assays

description: Despite the obvious importance of nectar, the composition of this solution remains surprisingly understudied to most of the flowers. Here we describe a simple, low-cost, and reliable methodology to analyze the three main sugars present in 210 nectar samples of Christmas Bellflowers using capillary electrophoresis (CE) and enzymatic assays. CE separation (-16 kV) was made using an electrolyte containing 36 mM NaOH pH 12, 15 mM sorbic acid, 0.5 mM hexadecyl trimethylammonium bromide (CTAB), and indirect UV detection. 72.9% of analyzed nectar samples were sucrose dominant; 13.3% sucrose rich only and 13.8% were fructose rich. The concentrations of fructose and glucose present in most of the samples were very similar, while the amount of sucrose varied considerably. The average amounts of fructose, glucose, sucrose and total sugar were 0.22, 0.21, 0.34 and 0.8 M, respectively. The nectar sample shows a pH average of 5. α-Glucosidase activity was observed in 65% of the samples with an average activity of 0.013 µU µL-1 providing a possible explanation for the similar concentrations of fructose and glucose in the samples. Under our knowledge, this is the first article that shows the analysis of sugars in nectar flowers using CE.
DOI: 10.6084/m9.figshare.14304008
title: Virtual Screening of Secondary Metabolites of the Family Velloziaceae J. Agardh with Potential Antimicrobial Activity

description: The objective of this work was to carry out a bibliographic survey of secondary metabolites isolated from the Velloziaceae family, creating a bank of compounds. After the bank was created, four prediction models for potentially active compounds against pathogenic microorganisms (Candida albicans, Escherichia coli, Pseudomonas aeruginosa and Salmonella sp.) were obtained trying to identify which metabolites would be more active against the strains. Four sets of compounds with known activity for microorganisms were selected for the construction of predictive models from the CHEMBL database. Another bank with 163 unique molecules isolated from the Velloziaceae family was built. The Volsurf+ v.1.0.7 software obtained the molecular descriptors and Knime 3.5 generated the in silico model. The performances of the internal and external tests were also analyzed. The study contributed through the virtual screening of a bank of metabolites to select several compounds with potential antimicrobial activity, highlighting the biflavonoid amentoflavone which showed potential activity against the four strains.
DOI: 10.6084/m9.figshare.14304006
title: One-Step Isolation of Monoterpene Indole Alkaloids from Psychotria leiocarpa Leaves and Their Antiviral Activity on Dengue Virus Type-2

description: The leaf MeOH extract of Psychotria leiocarpa (Rubiaceae) showed in vitro non-cytotoxic and anti-dengue virus serotype 2 (DENV2) activity in human hepatocarcinoma cell lineage (HepG2). A one-step and cost-effective reversed-phase solid-phase extraction method based on high-performance liquid chromatography (HPLC) parameters allowed the isolation, directly from this bioactive extract, of the monoterpene indole alkaloids: N-glucopyranosyl vincosamide (1), vincosamide (2) and strictosidinic acid (3). The chemical structures were characterized based on 1D and 2D nuclear magnetic resonance (NMR), UV and high-resolution mass spectra (HRMS). The methodology has also allowed yielding a polyphenolic-rich fraction that was analyzed by high-performance liquid chromatography coupled to diode array detection and electrospray ionization tandem mass spectrometry (HPLC-DAD-ESI-MS/MS) revealing two flavonol triglycosides (4, 5) and three caffeoylquinic acid isomers (6-8). Compound 3 is reported for the first time in P. leiocarpa and all the phenolic compounds (4-8) are described for the first time in the genus Psychotria. Compounds 1-3 showed to be non-cytotoxic and anti-dengue active towards DENV2, highlighting vincosamide (2).
DOI: 10.6084/m9.figshare.14304005
title: Isolation, Absolute Configuration and Cytotoxic Activities of Alkaloids from Hippeastrum goianum (Ravenna) Meerow (Amaryllidaceae)

description: The phytochemical study of Hippeastrum goianum led to the identification of 13 compounds by means of gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR). Compounds 7-demethoxy-9-O-methylhostasine (1) and 7-deoxi-trans-dihydronarciclasine (2) had their absolute configurations determined by vibrational circular dichroism (VCD). This is the first time that compound 1 is described in the Amaryllidaceae family. The cytotoxicity of all isolated compounds was tested against colorectal carcinoma (HCT 116), breast carcinoma (MCF-7), and non-tumor human retinal pigment epithelium (RPE) cell lines. The half-maximum inhibitory concentration (IC50) of compound 2 against each cell line was equivalent to the positive control (doxorubicin), indicating a considerable cytotoxic activity.
DOI: 10.6084/m9.figshare.14304002
title: Synthesis and Characterization of Hybrid Polymer Based on Functionalized Silica as Efficient Adsorbent for Heavy Metal Ions from Aqueous Solution

description: An organic-inorganic hybrid material based on a silica matrix and functionalized with imidazole group was successfully synthesized by the sol-gel process. The characterization techniques enabled the confirmation of the proposed structure as well as the effectiveness of the imidazole ring functionality in the structure of the material. It is insoluble in water and showed an anion exchange capacity of 2.944 mmol g-1, an excellent capacity for the adsorption of metal ions according to the literature. Thus, the metal halides CuCl2, CdCl2 and NiCl2 were adsorbed by the modified silsesquioxane from aqueous solutions. The adsorption isotherms results showed the availability of 3-n-propylimidazolium silsesquioxane chloride (SiImi+Cl-) as an efficient adsorbent material in the adsorption of metal ions, exhibiting a higher affinity for the Cu2+ ions at pH 4, with a maximum adsorption capacity of 2.80 mmol g-1. The Langmuir, Freundlich and Sips models were applied to the adsorption isotherms, both the pH and the nature of the ion were observed to be factors that influence the adjustment of the isotherms to the proposed models.