Brønsted-acid sites promoted degradation of phthalate esters over MnO2: Mineralization enhancement and aquatic toxicity assessment.

Advanced oxidation processes (AOPs) are important technologies for aqueous organics removal. Despite organic pollutants can be degraded via AOPs generally, high mineralization of them is hard to achieve. Herein, we synthesized a manganese oxide nanomaterial (H2-OMS-2) with abundant Brønsted-acid sites via ion-exchange of cryptomelane-type MnO2 (OMS-2), and tested its catalytic performance for the degradation of phthalate esters via peroxymonosulfate (PMS) activation. About 99% of dimethyl phthalate (DMP) at a concentration of 20 mg/L could be degraded within 90 min and 82% of it could be mineralized within 180 min over 0.6 g/L of catalyst and 1.8 g/L of PMS. The catalyst could activate PMS to generate SO4-˙ and ·OH as the dominant reactive oxygen species to reach complete degradation of DMP. Especially, the higher TOC removal rate was obtained due to the rich Brønsted-acid sites and surface oxygen vacancies on the catalyst. Kinetics and mechanism study showed that MnII/MnIII might work as the active sites during the catalytic process with a lower reaction energy barrier of 55.61 kJ/mol. Furthermore, the catalyst could be reused for many times through the regeneration of the catalytic ability. The degradation and TOC removal efficiencies were still above 98% and 65% after seven consecutive cycles, respectively. Finally, H2-OMS-2-catalyzed AOPs significantly reduced the organismal developmental toxicity of the DMP wastewater through the investigation of zebrafish model system. The present work, for the first time, provides an idea for promoting the oxidative degradation and mineralization efficiencies of aqueous organic pollutants by surface acid-modification on the catalysts.

Reductant free green synthesis of magnetically recyclable MnFe2O4@SiO2-Ag coreshell nanocatalyst for the direct reduction of organic dye pollutants.

The present paper describes in situ green immobilization of silver nanoparticles on MnFe2O4@SiO2 nanospheres using Epilobium parviflorum (EP) without using any other toxic chemicals and reducing or stabilizing agents. The morphology, composition, and magnetic properties of the resulting MnFe2O4@SiO2-Ag core-shell nanocatalyst were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). The catalytic performance of the synthesized MnFe2O4@SiO2-Ag was employed on the organic pollutants dyes such as rhodamine B (RhB) and methylene blue (MB). The results revealed significant reduction performances for the MB (116.28 s-1 g-1) and RhB (27.12 s-1 g-1) over the existing literature. Furthermore, the MnFe2O4@SiO2-Ag exhibited high stability for the completion of the reduction of RhB between the reaction times of 13.1 (first) and 19.8 min (final) with the 100% decolorization efficiency even after several cycles with an excellent magnetic separation. Overall, this work demonstrates a simple and practical green synthetic route for the preparation of magnetic recyclable core-shell nanocatalyst that can be a good candidate for the treatment of organic contaminants in wastewater adhering to green chemistry principles for the environmental pollution concerns.

A novel fluorescent probe based on isocoumarin for Hg2+ and Fe3+ ions and its application in live-cell imaging.

Synthesis of the 2-amino-4-phenyl-6- (isocoumarin-3-yl) -3-cyanopyridine (APICP) containing both isocoumarin and pyridine ring in its structure was carried out, and this compound was characterized by ATR-FTIR, 1H NMR, and 13C NMR spectral techniques. A fluorescence sensor determining Hg2+ and Fe3+ ions in DMSO/HEPES buffer solution (9/1 v/v, 5 µM, pH 7.0) was developed using the synthesized compound, and the detection limits of the sensor with exquisite selectivity were calculated as 8.12 nM and 5.51 nM for Hg2+ and Fe3+ ions, respectively. Jobs plot method was used to determine the stoichiometry of APICP-Hg2+/Fe3+ complexes as 2:1 and FT-IR and ESI-MS methods confirmed the results. Besides, cell growth inhibitory potentials of the sensor over HepG2 cells and in vivo fluorescent cell imaging experiments were conducted. Findings revealed the relatively low cytotoxic effects of the synthesized sensor (IC50: 0.541 ±â€¯0.039 mM), and it could be utilized as an intracellular imaging agent for the determination of Fe3+ and Hg2+ ions in biological systems.

Poly(amidoamine) dendrimer-coated magnetic nanoparticles for the fast purification and selective enrichment of glycopeptides and glycans.

Glycosylated proteins modulate various important functions of organisms. To reveal the functions of glycoproteins, in-depth characterization studies are necessary. Although mass spectrometry is a very efficient tool for glycoproteomic and glycomic studies, efficient sample preparation methods are required prior to analyses. In the study, poly(amidoamine) dendrimer-coated magnetic nanoparticles were presented for the specific enrichment and fast purification of glycopeptides and glycans. The enrichment and purification performance of the developed method was evaluated both at the glycopeptide, and the glycan level using several standard glycoprotein digests and released glycan samples. The poly(amidoamine) dendrimer-coated magnetic nanoparticles not only showed selective affinity (Immunoglobulin G/Bovine Serum Albumin, 1/10 by weight) to glycopeptides and released glycans but also good sensitivity (0.4 ng/µL for Immunoglobulin G) for glycoproteomic and glycomic applications. Thirty-five glycopeptides of Immunoglobulin G were detected after enrichment with poly(amidoamine) dendrimer-coated magnetic nanoparticles. In addition, 55 18 O tagged deamidated glycopeptides belonging to human plasma glycoproteome were confirmed. Finally, fifty 2-aminobenzoic acid, and 30 procainamide-labelled human plasma N-glycans released from human plasma glycoproteins were determined after purifications. The results indicate that the proposed enrichment and purification method using poly(amidoamine) dendrimer-coated magnetic nanoparticles could be simply adjusted to sample preparation methods.

Evaluation of Jeffamine® Core PAMAM Dendrimers for Simultaneous Removal of Divalent Heavy Metal Ions from Aqueous Solutions by Polymer Assisted Ultrafiltration.

Different generations (G3-G4) of amine-terminated Jeffamine® T-403 core poly(amidoamine) PAMAM dendrimers (JCPDs) were used as new macromolecular heavy metal chelating agent templates in polymer assisted ultrafiltration (PAUF) for the investigation of their removal ability for some of the divalent metal ions: Cu, Co, Ni, Cd, and Zn from aqueous solutions under competitive conditions. The effects of pH and generation size of JCPDs were also investigated. Extent of binding (EOB) data can be appropriately expressed by a tetradentate coordination for JCPDs at pH 9 where the maximum removal of metal ions was observed. At pH 9.0, the affinity of both generations towards heavy metal ions was also observed in the decreasing order of Zn(II) > Co(II) > Ni(II) > Cu(II) > Cd(II). Results revealed that the highest total binding capacity was observed for G3-NH2 (262.79 ± 1.62 mg/g) as a little bit higher than that of G4-NH2 (257.27 ± 2.57 mg/g). EOB studies also proved the active contribution of amide groups to metal binding ability of PAMAMs. Both generations were selective towards Cu(II) ions at lower pH 5 and pH 7. From these results, it was concluded that studied JCPDs have the desired technical properties to be used for the removal of toxic metals from wastewaters.

Synthesis of surface-modified TREN-cored PAMAM dendrimers and their effects on the solubility of sulfamethoxazole (SMZ) as an analog antibiotic drug.

Sulfamethoxazole (SMZ) is a sulfonamide and used widely in the treatment of bacteriostatic and urinary tract infections with trimethoprim as an antibiotic. The problem with SMZ is its poor water solubility, therefore, low bioavailability in clinical applications. In this study, we synthesized new-generation Tris(2-aminoethyl)amine (TREN)-cored amine (NH2), Tris(hydroxymethyl)aminomethane (TRIS), and carboxyl (COOH) terminated different generations T2-T4 poly(amidoamine) PAMAM dendrimers. Synthesized PAMAMs were characterized by 1H NMR, 13C NMR, ATR-FTIR, spectroscopic titrations, and evaluated as potential solubility enhancers and drug carriers of sulfonamides by taking SMZ as a model drug. The effect of concentration, generation, and surface groups of PAMAMs on the solubility of SMZ was also investigated. Results showed that the solubility of SMZ improved significantly with an increasing generation size (T2-T4) and PAMAM dendrimer concentration (0-2 mM). The role of PAMAMs in the solubility enhancement of SMZ was in the order of T4.NH2 > T4.COOH > T3.NH2 > T4.TRIS > T2.NH2 > T3.COOH > T3.TRIS > T2.COOH > T2.TRIS, and in the ranges of 5- to 45-fold with maximum SMZ loading 7 to 61 mole/mole per PAMAM dendrimer molecule. In vitro release studies demonstrated that SMZ-PAMAM dendrimer complexes at the end of 2-h drug release (16-26%) was considerable slower than pure SMZ (38.8%).

The effect of PAMAM dendrimer concentration, generation size and surface functional group on the aqueous solubility of candesartan cilexetil.

This article investigates the aqueous solubility of the poorly soluble drug candesartan cilexetil (CC) in the presence of poly(amidoamine) (PAMAM) dendrimers. The effect of variables such as concentration, generation size (G2-G4), and surface groups (NH2, COOH and TRIS) of PAMAMs on the aqueous solubility of CC was studied. A two-factor factorial (3 × 3) ANOVA design was used to study the effect of generation size and surface functional group of the PAMAMs. The results showed that the aqueous solubility of CC in the presence of carboxyl and TRIS-terminated PAMAMs was higher than those of amine-terminated PAMAMs, and the effect of surface functional group of the PAMAMs on the aqueous solubility of CC was dependent on the generation size (p < 0.05). The sequence of the observed solubility fold enhancement due to PAMAMs was G4.COOH (8378)>G3.COOH (3456)>G4.TRIS (2362)>G2.COOH (1013)>G3.TRIS (749)>G2.TRIS (293)>G4.NH2 (91)>G3.NH2 (50)>G2.NH2 (37). The CC-PAMAM dendrimer inclusion complexes were characterized by UV-Vis, attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and differential thermal analysis (DTA) techniques. Regarding the results of these techniques, improvement in the solubility of CC is expected primarily through the intermolecular hydrogen bonding between the drug and internal tertiary and surface functional groups of the studied PAMAMs.

Preparation of Cu Nanocomposites from EDA, DETA, and Jeffamine Cored PAMAM Dendrimers with TRIS and Carboxyl Surface Functional Groups.

This study presents the synthesis and UV-Vis characterization of Cu nanocomposites from ethylenediamine (EDA) (E), diethylenetriamine (DETA) (D), and Jeffamine® T-403 (P) cored PAMAM dendrimers (PAMAMs) with TRIS and carboxyl surface functional groups. Cu-PAMAM dendrimer encapsulated nanoparticles (Cu-DENs) were characterized by UV-Vis spectroscopy. Disappearance of the 680 nm d-d transition and 270-300 nm ligand to metal charge transfer (LMCT) peaks and the formation of monotically increasing exponential band were used as the evidence of the successful synthesis of Cu-DENs in addition to immediate color change of dendrimer-metal mixture solutions from blue to golden brown by reduction. Synthesized Cu-DENs could be facilitated as novel alternatives to the existing nanomaterials used in a wide range of applications involving bio and chemical sensors, catalysis, hydrogenations, oxidations, semiconductors, noble metals, magnetic dendrimer nanocomposites, environmental cleanup and many others.

Cytotoxicity and in vitro characterization studies of synthesized Jeffamine-cored PAMAM dendrimers.

The objective of this study is to make comprehensive cytotoxicity evaluation and in vitro characterization of Jeffamine-cored polyamidoamine (PAMAM) dendrimers on L929 cell lines for oral drug delivery purposes. Ester-, amine- and carboxylic acid-terminated PAMAMs were investigated for their cytotoxicity on L929 cells at different generations and concentrations. Cationic surface charge caused highest cytotoxicity on L929 cells, while ester-terminated PAMAMs showed generation- and concentration-dependent toxicity. Anionic dendrimers were determined as the lowest cytotoxic group, and highest generation number presented lowest cellular toxicity. Encapsulation studies were performed with anionic PAMAMs at 2.5, 3.5 and 4.5 generations and different concentrations. Increasing generation number provides greater loaded naproxen amounts and larger particle size. Moreover, formulations provide controlled release at simulated terminal ileum conditions. Consequently, Jeffamine-cored carboxylic acid-terminated PAMAMs can be a promising option for oral drug delivery of poorly water-soluble drugs.