Linear Polyethyleneimine-Based and Metal Organic Frameworks (DUT-67) Composite Hydrogels as Efficient Sorbents for the Removal of Methyl Orange, Copper Ions, and Penicillin V.

This research explores the integration of DUT-67 metal organic frameworks into polyethyleneimine-based hydrogels to assemble a composite system with enough mechanical strength, pore structure and chemical affinity to work as a sorbent for water remediation. By varying the solvent-to-modulator ratio in a water-based synthesis path, the particle size of DUT-67 was successfully modulated from 1 µm to 200 nm. Once DUT-67 particles were integrated into the polymeric hydrogel, the composite hydrogel exhibited enhanced mechanical properties after the incorporation of the MOF filler. XPS, NMR, TGA, FTIR, and FT Raman studies confirmed the presence and interaction of the DUT-67 particles with the polymeric chains within the hydrogel network. Adsorption studies of methyl orange, copper(II) ions, and penicillin V on the composite hydrogel revealed a rapid adsorption kinetics and monolayer adsorption according to the Langmuir's model. The composite hydrogel demonstrated higher adsorption capacities, as compared to the pristine hydrogel, showcasing a synergistic effect, with maximum adsorption capacities of 473 ± 21 mg L-1, 86 ± 6 mg L-1, and 127 ± 4 mg L-1, for methyl orange, copper(II) ions, and penicillin V, respectively. This study highlights the potential of MOF-based composite hydrogels as efficient adsorbents for environmental pollutants and pharmaceuticals.

Shared Hydrogen Atom Location and Chemical Composition in Picolinic Acid and Pyridoxal Hydrochloride Derivatives Determined by X-ray Crystallography.

Three new single-crystal structures were isolated for picolinic acid (2), the trifluoroacetate salt of picolinic acid (1), and pyridoxal hydrochloride (3). These compounds displayed unconventional crystallographic features that must be considered when structural refinements are carried out. Thus, the generated Fourier differences map obtained with the diffraction data collected at 100 K was crucial to visualize electron densities, which were balanced by either one hydrogen atom or a hydrogen atom with an occupancy factor of 1/2 located between either two carboxylate moieties, two phenolic oxygen atoms, or two pyridinic nitrogen atoms. Moreover, NMR studies were conducted to analyze the bulk chemical composition of single crystals of 2-pyridinecarboxylic acid obtained from the gem-diol/hemiacetal forms and the polymerization products after the treatment of 2-pyridinecarboxaldehyde with TFA:H2O (1) or a diluted Cu(NO3)2 solution (2). The quantitative yield of the pyridoxal hydrochloride crystalline material (3) obtained from a diluted CuCl2 solution was exhaustively characterized by solid-state NMR methods. These methods allowed the resolution of the signals corresponding to the protons of the hydroxyl moiety of the intramolecular hemiacetal group and the phenolic hydrogen. Theoretical calculations using DFT methods were done to complement the atomic location of the hydrogen atoms obtained from the X-ray analysis.

Solid-State Characterization of Acetylpyridine Copper Complexes for the Activation of H2 O2 in Advanced Oxidation Processes.

This work describes the synthesis of 4-(4-AcPy) and 3-acetylpyridine (3-AcPy) copper soluble complexes for the activation of hydrogen peroxide and the concomitant generation of reactive oxygen species (ROS). Given the paramagnetic effects of copper ions in the Nuclear Magnetic Resonance (NMR) lines, we aimed at demonstrating that the combination of high-resolution 2D solid-state NMR experiments, Electron Paramagnetic Resonance (EPR), single-crystal X-ray crystallography and Density Functional Theory (DFT) calculations allows a detailed study of the chemical structure of the ligands and the surrounding metal ions. The copper complexes synthesized with CuCl2 were useful for the activation of H2 O2 during which the only ROS was the hydroxyl one, as demonstrated by EPR experiments. A removal of methyl orange (MO) azo-dye higher than 85 % was achieved in 200 minutes, combining 1.7 mM of copper complexes with 60 mM of H2 O2 and 40 µM of MO.

S, N-doped carbon dots-based cisplatin delivery system in adenocarcinoma cells: Spectroscopical and computational approach.

S and N-doped carbon dots (S-CDs and N-CDs) and their cisplatin (cis-Pt) derivatives. (S-CDs@cis-Pt and N-CDs@cis-Pt) were tested on two ovarian cancer cell lines: A2780 and A2780 cells resistant to cis-Pt (A2780R). Several spectroscopic techniques were employed to check S-CDs@cis-Pt and N-CDs@cis-Pt: solid- and solution-state nuclear magnetic resonance, matrix-assisted laser desorption, ionization time-of-flight mass spectrometry, and X-ray photoelectron spectroscopy. In addition, synchrotron-based Fourier Transformed Infrared spectro-microscopy was used to evaluate the biochemical changes in cells after treatment with cis-Pt, S-CDs, N-CDs, or S-CDs@cis-Pt and N-CDs@cis-Pt, respectively. Computational chemistry was applied to establish the model for the most stable bond between S-CDs and N-CDs and cis-Pt. The results revealed the successful modification of S-CDs and N-CDs with cis-Pt and the formation of a stable composite system that can be used for drug delivery to cancer cells and likewise to overcome acquired cis-Pt resistance. Nanoparticle treatment of A2780 and A2780R cells led to the changes in their structure of lipids, proteins, and nucleic acids depending on the treatment. The results showed the S-CDs@cis-Pt and N-CDs@cis-Pt might be used in the combination with cis-Pt to treat the adenocarcinoma, thus having a potential to be further developed as drug delivery systems.

Paramagnetic solid-state NMR assignment and novel chemical conversion of the aldehyde group to dihydrogen ortho ester and hemiacetal moieties in copper(ii)- and cobalt(ii)-pyridinecarboxaldehyde complexes.

The complex chemical functionalization of aldehyde moieties in Cu(ii)- and Co(ii)-pyridinecarboxaldehyde complexes was studied. X-ray studies demonstrated that the aldehyde group (RCHO) of the four pyridine molecules is converted to dihydrogen ortho ester (RC(OCH3)(OH)2) and hemiacetal (RCH(OH)(OCH3)) moieties in both 4-pyridinecarboxaldehyde copper and cobalt complexes. In contrast, the aldehyde group is retained when the 3-pyridinecarboxaldehyde ligand is complexed with cobalt. In the different copper complexes, similar paramagnetic 1H resonance lines were obtained in the solid state; however, the connectivity with the carbon structure and the 1H vicinities were done with 2D 1H-13C HETCOR, 1H-1H SQ/DQ and proton spin diffusion (PSD) experiments. The strong paramagnetic effect exerted by the cobalt center prevented the observation of 13C NMR signals and chemical information could only be obtained from X-ray experiments. 2D PSD experiments in the solid state were useful for the proton assignments in both Cu(ii) complexes. The combination of X-ray crystallography experiments with DFT calculations together with the experimental results obtained from EPR and solid-state NMR allowed the assignment of NMR signals in pyridinecarboxaldehyde ligands coordinated with copper ions. In cases where the crystallographic information was not available, as in the case of the 3-pyridinecarboxaldehyde Cu(ii) complex, the combination of these techniques allowed not only the assignment of NMR signals but also the study of the functionalization of the substituent group.

Targeted anti-inflammatory peptide delivery in injured endothelial cells using dermatan sulfate/chitosan nanomaterials.

This work describes a novel delivery system for targeting egg-derived anti-inflammatory tripeptide Ile-Arg-Trp (IRW) to endothelial cells. The nanomedicine is synthesized by a simple and reproducible ionotropic gelification method that results in the efficient loading of the positively charged IRW within the dermatan sulfate/ chitosan matrix, as demonstrated by ss-NMR spectroscopy. The incorporation of IRW results in a stable nanoparticle dispersion with a single size population of 442 ±â€¯43 nm. Fluorescence microscopy studies demonstrate the capacity of the nanomaterial to distinguish between a quiescent and an injured endothelium through the interaction of dermatan sulfate with the CD44 receptor. Remarkably, no additional surface functionalization is required as dermatan sulfate mediates their internalization and the intracellular release of this natural anti-inflammatory tripeptide to modulate endothelial inflammatory response. This simple, scalable, and versatile nanotechnology platform opens new opportunities to apply in the therapy of vascular disease.

Insights into the formation of N doped 3D-graphene quantum dots. Spectroscopic and computational approach.

In this work, we utilize a top-down approach to synthesize nitrogen doped graphene quantum dots from a 3D-graphene precursor via an eco-friendly hydrothermal method. The nanoparticles obtained showed a 2-3 nm diameter and well dispersion behavior in aqueous media. The reaction mechanism of insertion of nitrogen from polyvinylpolypyrrolidone onto the 3D-graphene structure, via an esterification reaction, was studied by the density functional theory, in addition, the kinetic and thermodynamic magnitudes of the reaction was analyzed with the help of Eyring's transition state theory and statistical thermodynamics. After analysis by ss-NMR and XPS spectroscopies, the functional groups involved in this process were characterized, and N was found mainly as amide/amine groups. Fluorescence emission, which exhibited a red shift (552 nm) and an emission maximum at 512 nm when excited at 480 nm, demonstrated a low stoke shift (Δλ = 32 nm), explained by the proposed structural model.

Interaction of Carbohydrate Coated Cerium-Oxide Nanoparticles with Wheat and Pea: Stress Induction Potential and Effect on Development.

: Reports about the influence of cerium-oxide nanoparticles (nCeO2) on plants are contradictory due to their positive and negative effects on plants. Surface modification may affect the interaction of nCeO2 with the environment, and hence its availability to plants. In this study, the uncoated and glucose-, levan-, and pullulan-coated nCeO2 were synthesized and characterized. The aim was to determine whether nontoxic carbohydrates alter the effect of nCeO2 on the seed germination, plant growth, and metabolism of wheat and pea. We applied 200 mgL-1 of nCeO2 on plants during germination (Ger treatment) or three week-growth (Gro treatment) in hydroponics. The plant response to nCeO2 was studied by measuring changes in Ce concentration, total antioxidative activity (TAA), total phenolic content (TPC), and phenolic profile. Our results generally revealed higher Ce concentration in plants after the treatment with coated nanoparticles compared to uncoated ones. Considering all obtained results, Ger treatment had a stronger impact on the later stages of plant development than Gro treatment. The Ger treatment had a stronger impact on TPC and plant elongation, whereas Gro treatment affected more TAA and phenolic profile. Among nanoparticles, levan-coated nCeO2 had the strongest and positive impact on tested plants. Wheat showed higher sensitivity to all treatments.

Kinetic and equilibrium adsorption of two post-harvest fungicides onto copper-exchanged montmorillonite: synergic and antagonistic effects of both fungicides' presence.

The simultaneous adsorption of both imazalil (IMZ) and thiabendazole (TBZ) fungicides in a Cu2+-exchanged Mt was studied in this work. Kinetic studies were used to determine the rate law which describes the adsorption of individual fungicides onto the adsorbent. Adsorption isotherm of individual and combined fungicides was done to evaluate synergic or antagonistic effects. The Mt-Cu material considerably improved TBZ and/or IMZ adsorption from aqueous suspensions with respect to raw Mt, leading to removal efficiencies higher than 99% after 10 min of contact time for TBZ and IMZ Ci = 15 and 40 mg/L, respectively, when a solid dosage = 1 g/L was used. The adsorption sites involved were determined by a combination of X-ray diffraction (XRD) determinations and electron paramagnetic resonance (EPR), indicating that fungicides were bonded to Cu2+ cations, while the rate limiting step was the formation of coordination bonds. The adsorption mechanism proposed is that of ligand exchange between water and fungicide molecules in the metal coordination sphere. The single-crystal structure for the IMZ-Cu2+ complex indicated that four molecules were bounded to the copper centers, while two molecules of TBZ are bounded to copper explaining the higher IMZ uptake capacity for the Mt-Cu material. Graphical abstract.

Sulfanilic acid-modified chitosan mini-spheres and their application for lysozyme purification from egg white.

A cation exchange matrix with zwitterionic and multimodal properties was synthesized by a simple reaction sequence coupling sulfanilic acid to a chitosan based support. The novel chromatographic matrix was physico-chemically characterized by ss-NMR and ζ potential, and its chromatographic performance was evaluated for lysozyme purification from diluted egg white. The maximum adsorption capacity, calculated according to Langmuir adsorption isotherm, was 50.07 ± 1.47 mg g-1 while the dissociation constant was 0.074 ± 0.012 mg mL-1 . The process for lysozyme purification from egg white was optimized, with 81.9% yield and a purity degree of 86.5%, according to RP-HPLC analysis. This work shows novel possible applications of chitosan based materials. The simple synthesis reactions combined with the simple mode of use of the chitosan matrix represents a novel method to purify proteins from raw starting materials. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 34:387-396, 2018.

Dermatan sulfate/chitosan polyelectrolyte complex with potential application in the treatment and diagnosis of vascular disease.

Cardiovascular disease is the largest single cause of morbid-mortality in the world. However, there is still no pharmaceutical treatment that directly targets the blood vessel wall instead of just controlling the risk factors. Here, we produced polyelectrolyte complexes (PECs) by a simple and reproducible polyelectrolyte complexation method between low molecular mass dermatan sulfate (polyanionic polysaccharide) and chitosan (polycationic polysaccharide), and evaluated the cellular uptake by vascular endothelial cells. The composition and the composition homogeneity of PECs were confirmed by (13)C-CP-MAS spectroscopy and by polyacrylamide gel electrophoresis, respectively. The hydrodynamic radius, determined by dynamic light scattering, was 729±11nm. PECs were not cytotoxic for a murine heart endothelium-derived cell line. Fluorescent confocal microscopy showed the specific uptake of fluorescently-labeled PECs by endothelial cells when they were cultured alone or in the presence of macrophages. Overall, these findings confirmed the potential of these PECs for targeting different agents to the vessel wall in the prevention, diagnosis, and therapy of vascular disease.