Introduction Of Amino Group Research Articles

Functionalized chitosan electrospun nanofiber membranes for heavy-metal removal

In order to improve the removal ability of chitosan (CS) to heavy metal ions, in this study, rich amino-functionalized CS electrospun membranes have been prepared. During the efficient synthesis, poly (glycidyl methacrylate) (PGMA) and polyethylenimine (PEI) were sequentially grafted on the surface of CS electrospun membrane. The success of introduction of amino-group on the CS were confirmed by X-ray diffractometer (XRD), attenuated total reflection-fourier transform infrared (ATR-FTIR), and X-ray photoelectron spectroscopy (XPS). The ability of remove heavy metal ions (Cr(VI), Cu(II) and Co(II)) of the as-prepared membrane (CS-PGMA-PEI) was investigated. The adsorption equilibrium of the heavy metal ion solutions was rapidly established in 60 min. Adsorption kinetics analysis reveals that the adsorption process of CS-PGMA-PEI electrospun membrane was dominated by a Pseudo-second-order model. Its adsorption isotherm can be described by the Langmuir model. The maximum adsorption capacities calculated by Langmuir model were 138.96, 69.27 and 68.31 mg g −1 for Cr(VI), Cu(II) and Co(II), respectively. The adsorption ability of CS-PGMA-PEI electrospun membrane toward metal ions was found in an order of Cr(VI) > Cu(II) > Co(II). CS-PGMA-PEI membrane also exhibited a good reproducibility and stability. Our study may provide a way to synthesize membranes for water purification.

Surface chemical functionalization of starch nanocrystals modified by 3-aminopropyl triethoxysilane

A comparative experiment about the 3‑aminopropyl triethoxysilane (APTES) modification of waxy potato starch nanocrystals (WPSNCs) and waxy maize starch nanocrystals (WMSNCs) was employed in the present study. The purpose of surface chemical functionalization was to introduce functional groups and improve hydrophobicity of SNCs for the extensive application. The degree of substitution (DS) of both SNCs displayed the upward trend with the increase of applied APTES, while WPSNCs showed higher DS than that of WMSNCs in the same dosage of APTES. XRD revealed the un-changed crystalline structure and decreased relative crystallinity after the modifications. The structure of silylated SNCs surface was characterized by FT-IR and XPS, which confirmed the presence of functional amino groups. The introduction of amino groups resulted in a simultaneous enhancement of zeta potentials for both SNCs relatively. The modified SNCs could be uniformly dispersed both in water and ethanol phase revealing improved hydrophobicity through wettability experiments.

Rapid immunofluorescence assay for staphylococcal enterotoxin A using magnetic nanoparticles

SummaryA competitive immunoassay for staphylococcal enterotoxin A (SEA) detection in milk was developed, using immobilised antibody onto magnetic nanoparticles (MNPs). MNPs were prepared and then modified to introduce amino groups on them. The morphology and size of the obtained both unmodified and modified MNPs were characterized using TEM analyses. Monoclonal anti‐SEA antibody was immobilised onto the modified MNPs (MNP‐Ab). Staphylococcal enterotoxin A was conjugated with fluorescent dye ATTO620NHS. The characteristics of fluorescence conjugate were examined. The amount of MNP‐Ab and concentration of the fluorescent conjugate used for competitive immunoassay were optimized: 0.25 mg and 53 μg mL−1, respectively. The detection limit of developed immunoassay was determined – 0.23 ng mL−1 SEA in spiked milk samples. The immunoassay takes only 30 min, the magnetic separation is fast (<10 s) and the volume of the sample for analysis is very small (200 μL).

Salts formation between ibuprofen and pyridine derivatives: Effect of amino group on supramolecular packing and proton transfer

Cocrystal-salt continuum study is important to pharmaceutical industry, for which the empirical ΔpKa rules are not always applicable and a deep understanding is still required. In this present study, multicomponent crystals of ibuprofen (IBU) were screened and investigated based on pyridine-containing systems. Amino group was introduced in pyridine ring to examine its effect on salt/cocrystal formation. 4 new salts of IBU with 4-aminopyridine (4AP), 2-amino-5-methylpyridine (2A5MP), 3-methyl-4-aminopyridine (3M4AP) and 2,6-diaminopyridine (26DAP) were synthesized and characterized by X-ray diffraction (XRD), differential Scanning Calorimetry (DSC), Thermo gravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FT-IR). The crystal packing diagrams of three salts (S-IBU•4AP, 1:1; S-IBU•2A5MP, 1:1; RS-IBU•26DAP, 1:1) and one salt hydrate (S-IBU•3M4AP•H2O, 2:2:3) showed that the introduced amino groups are not involved in the proton transfer but play an important role in the hydrogen bond network. The ortho and para-amino groups of coformers can form ring motif to stabilize the structures. Meanwhile, the amino groups were found to enhance the electronegativity of pyridine nitrogen, to which the proton is easier to be transferred. The Hirshfeld surfaces analysis of the four new salts revealed that the structures are mainly stabilized by O⋯H, H⋯H and C⋯H interactions.

An electrochemical immunobiosensor for ultrasensitive detection of Escherichia coli O157:H7 using CdS quantum dots-encapsulated metal-organic frameworks as signal-amplifying tags

We report here cadmium sulfide quantum dots (CdS QDs)-encapsulated metal-organic frameworks as signal-amplifying tags for ultrasensitive electrochemical detection of Escherichia coli O157:H7 (E. coli O157:H7). CdS QDs were encapsulated in zeolitic imidazolate framework-8 (ZIF-8) to form CdS@ZIF-8 muti-core-shell particles by in situ growth of ZIF-8 in the presence of CdS QDs. To specifically recognize E. coli O157:H7 cells, CdS@ZIF-8 particles were coated with polyethyleneimine to introduce amino groups on their surfaces, followed by surface modification of anti-E. coli O157:H7 antibody. A sandwich-type electrochemical immunobiosensor for the detection of E. coli O157:H7 was fabricated using CdS@ZIF-8 particles as signal tags. Cd(II) ions were released from CdS@ZIF-8 tags by HCl leaching, enabling the detection of E. coli O157:H7 by differential pulse voltammetry. Under the optimized conditions, the linear range of the biosensor is from 10 to 108 colony forming units (CFU) per mL for E. coli O157:H7 detection, with the detection limit of 3 CFU mL−1 (S/N = 3). The sensitivity of the biosensor for E. coli O157:H7 detection using CdS@ZIF-8 particles as signal tags is 16 times that of a biosensor using CdS QDs as signal tags, because the number of CdS QDs labeled to each bacterial cell increases greatly resulting from a great number of CdS QDs encapsulated in each CdS@ZIF-8 label. This method was successfully used to detect E. coli O157:H7 in milk samples.

Modification and Characterization of Nano-TiO2 for Efficient Fixation on Cotton Fibers

In this paper, a silane coupling agent, 3-aminopropyltriethoxysilane, was reacted with nano-TiO2 to introduce amino group onto it which was then reacted with trichlorotriazine to obtain a dichlorotriazine functionalized nano-TiO2 for the firm fixation of it on cotton fibers. The reaction process was monitored by the titration of primary and secondary amino groups, and the reaction conditions were optimized with orthogonal method accordingly. The dichlorotriazine functionalized nano-TiO2 was reacted with cotton fabric by the nucleophile substitution reaction to afford nano-TiO2 functionalized cotton fabric, the structure and surface morphology of the nano-TiO2 finished cotton fibers were studied by FT-TR and SEM. In addition, the fixation duration of the nano-TiO2 modified cotton was studied according to AATCC test method 61–2010. The results show that the washing fastness of the nano-TiO2 is excellent.

286 - Pegylated manganese protoporphyrin self-assembles into nanoparticles in aqueous media and exerts potent catalase-mimic activity to protect oxidative cellular damages

Certain types of metalloporphyrin derivatives have been studied their therapeutic potentials against oxidative stress related diseases according to their catalase-mimic activities. Here we describe the synthesis, physicochemical properties, and catalase-like activity of polyethylene glycol (PEG) conjugated manganese protoporphyrin (PEG-MnPP). Carboxyl groups of protoporphyrin ring at C6 and C7 positions were first activated by ethyl chloroformate, followed by reacting with tert-butoxycarbonyl (Boc)-ethylenediamine. Boc moieties were then removed to introduce amino groups onto protoporphyrin structure. To the amino groups were conjugated with succinimidyl PEG having average molecular weight of 2000 to obtain pegylated protoporphyrin (PEG-PP). Manganese was chelated into protoporphyrin ring to synthesize PEG-MnPP by incubating PEG-PP and manganese acetate in methanol. PEG-MnPP was highly water-soluble; the saturated concentration of PEG-MnPP in water was determined to be approximately 3 mM. Dynamic light scattering and fluorescent spectrometry analyses revealed that PEG-MnPP self-assembled into nanoparticles with micelle-like structure consisting of hydrophobic MnPP core surrounded by hydrophilic PEG chains in aqueous media having apparent molecular size of 400 nm in a diameter. PEG-MnPP can effectively eliminate hydrogen peroxide from culture media and protected mammalian cultured cells from toxic insults induced by hydrogen peroxide exposure. Intravenous administration of PEG-MnPP reduced liver injury of mice treated with acetaminophen. These data warrant further study to explore therapeutic potential of PEG-MnPP as water-soluble metalloporphyrin-based catalase mimic to oxidative stress associated diseases.

Removal of Cr(VI) from Aqueous Solutions Using Amino-Functionalized Carbon Nanospheres Adsorbents.

Carbon nanospheres were prepared and functionalized with carboxyl acid groups (CNS-CA), then reacted with 3-aminopropyltriethoxysilane to introduce amino groups onto the surface (CNS-NH₂) by post-synthesis grafting. CNS-NH₂ was acidified in order to convert the amino groups (-NH₂) into ammonium moieties (<inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="01925-ilm01.gif"/>). Various techniques such as N₂ physisorption, X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, thermogravimetry, X-ray photoelectron spectroscopy, and transmission electron microscopy were used to characterize the nanospheres. The removal of chromium ions from aqueous solution using <inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="01925-ilm12.gif"/> was investigated. Factors influencing the uptake of Cr(VI) ions such as solution pH, adsorbent dose, and initial Cr(VI) ion concentration were investigated. Equilibrium adsorption data fitted the Langmuir model very well. The adsorption maximum capacity of Cr(VI) was found to be 52.38 mg/g. The reusability of <inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="01925-ilm23.gif"/> results indicated that it can be reused five times successfully without loss of adsorption capacity.

Amino‐functionalized material from a bio‐template for silver adsorption: process evaluation in batch and fixed bed

AbstractBACKGROUNDThe modification of an organic matrix as a bio‐template (grapefruit peel) using urea and melamine was carried out to introduce amino groups on its surface and favor Ag(I) adsorption in aqueous solution for metal recovery.RESULTSAdsorption capacity in batch mode was proportional to the nitrogen content within the adsorbents, the maximum being the one obtained with the adsorbent functionalized with urea, 72.33 mg g−1, which was tested as a fixed bed in a column to evaluate the metal adsorption in a continuous flow model. The adsorption capacity of the fixed bed was 15.14 mg g−1, and its use was proved over three adsorption–desorption cycles.CONCLUSIONAmino‐functionalized adsorbent achieved a high Ag+ uptake capacity; from the characterization it is proposed that the adsorption mechanism consists in the formation of the complex R‐NH2Ag+ and R‐COOAg. © 2018 Society of Chemical Industry

Introduction of amino groups into polyphosphazene framework supported on CNT and coated Fe3O4 nanoparticles for enhanced selective U(VI) adsorption

A CNT-modified composite (namely, NH2-PZS/CNT/Fe3O4) was prepared and used for the removal of U(VI) from aqueous solution. The composite was synthesized using Fe3O4 nanoparticles with polyphosphazene-based polymer coating on CNTs. Experiments were carried out to investigate the influence of pH, concentration, contact time and temperature on the U(VI) removal process. The maximum adsorption capacity was calculated as 250 mg/g by considering Langmuir isotherm model and the adsorption process was also explained with pseudo-second-order kinetics. Adsorption tests in the presence of competing ions exhibited high selectivity for U(VI). The thermodynamic parameters indicate that the process was spontaneous and endothermic. The interaction mechanism of U(VI) with NH2-PZS/CNT/Fe3O4 was systematically clarified by using X-ray photoelectron spectroscopy (XPS) and Fourier transformation infrared (FTIR). Overall, the prepared NH2-PZS/CNT/Fe3O4 composite, which displayed important advantages such as re-usability, high adsorption capacity and selectivity, is a good adsorbent candidate for the removal of U(VI) from wastewater.

Synthesis of Novel Chitin Derivatives Bearing Amino Groups and Evaluation of Their Antifungal Activity.

Chemical modification is one of the most effective methods to improve the biological activity of chitin. In the current study, we modified C3-OH and C6-OH of chitin (CT) and successfully synthesized 6-amino-chitin (NCT) and 3,6-diamino-chitin (DNCT) through a series of chemical reactions. The structure of NCT and DNCT were characterized by elemental analyses, FT-IR, 13C NMR, XRD, and SEM. The inhibitory effects of CT, NCT, and DNCT against six kinds of phytopathogen (F. oxysporum f. sp. cucumerium, B. cinerea, C. lagenarium, P. asparagi, F. oxysporum f. niveum, and G. zeae) were evaluated using disk diffusion method in vitro. Meanwhile, carbendazim and amphotericin B were used as positive controls. Results revealed that 6-amino-chitin (NCT) and 3,6-diamino-chitin (DNCT) showed improved antifungal properties compared with pristine chitin. Moreover, DNCT exhibited the better antifungal property than NCT. Especially, while the inhibition zone diameters of NCT are ranged from 11.2 to 16.3 mm, DNCT are about 11.4–20.4 mm. These data demonstrated that the introduction of amino group into chitin derivatives could be key to increasing the antifungal activity of such compounds, and the greater the number of amino groups in the chitin derivatives, the better their antifungal activity was.

Chemically Grafted Aminated Carbon Nanotubes and l-Lysine in Ultramodified Conditions for Carbon Dioxide Storage.

The study reported CO2 storage properties of single-walled carbon nanotubes (CNTs) modified by introducing amino groups onto CNT surfaces via a chemical process. Two different approaches were used to produce amino-functionalized nanotubes by adding lithium amide and l-lysine amino acid. Lithium amide was introduced on CNT surfaces, and then, it was further modified by adding amino-moiety (l-lysine amino acid) to obtain multiamino sites on the CNT surface for CO2 storage. The aminated CNT were followed by CO2 adsorption experiments, and amino group interactions with CO2 have helped CNT to achieve higher adsorption capacity. The successful modification of CNTs showed ameliorated CO2 storage capacity as compared to pristine CNT. The modified CNT possessed free amine groups on the surface, which led to an enhanced CO2 adsorption capacity. The modified CNT samples were analyzed by X-ray photoelectron spectroscopy, infrared spectroscopy, and X-ray diffraction techniques.

Amino-Modified Fe-Terephthalate Metal–Organic Framework as an Efficient Catalyst for the Selective Oxidation of H2S

Classical amino-functionalized Fe-terephthalate metal-organic framework NH2-MIL-53(Fe) and its parent framework MIL-53(Fe) were prepared via simple hydrothermal methods. The catalytic performaces of these two Fe-MOFs were explored for the selective oxidation of H2S. The physicochemical properties of the fresh and used Fe-MOFs catalysts were investigated by XRD, BET, SEM, FT-IR, CO2-TPD, and XPS techniques. It was found that the introduction of amino groups reduces the activation energies for H2S oxidation and endows this catalyst surface with moderate basic sites. As a result, the NH2-MIL-53(Fe) catalyst displays high H2S conversion and near 100% S selectivity in the temperature range of 130-160 °C, outperforming commercial Fe2O3 and activated carbon. Moreover, a plausible reaction route for H2S selective oxidation over NH2-MIL-53(Fe) is proposed. This work opens up the possibility of utilizing MOFs as efficient catalyst for desulfuration reactions.

Effects of different silanization followed via the sol-gel growing of silica nanoparticles onto carbon fiber on interfacial strength of silicone resin composites

Effects of different silanization followed via the sol-gel growing of silica nanoparticles (SiO2) onto carbon fibers (CFs) on interfacial strength of silicone resin composites were investigated systematically. CFs were grafted with 3-aminopropyltriethoxysilane (APS) at different conditions to introduce amino groups (CF-NH2) or ethoxy groups (CF-Siloxane) for improving interfacial interaction between CFs and SiO2. Experimental results indicated that SiO2 was grown onto different functionalized CFs successfully, which enhanced the wettability owing to the increases of fiber polarity and surface roughness. Interlaminar shear strength (ILSS) and interfacial shear strength (IFSS) of SiO2 modified CFs composites enhanced significantly, especially for CF-Siloxane grafted with SiO2 (CF-Siloxane-SiO2), increasing 46.79% in ILSS and 39.61% in IFSS. Additionally, the introduced SiOC bonds increased hydrothermal aging resistance of the resulting composites greatly.

Gold‐Catalyzed C−H Imidation of Polycyclic Aromatic Hydrocarbons

AbstractAmino group is one of the most ubiquitous functional groups, and therefore the direct introduction of amino groups into arenes has gained much attention. Methods for installing amino groups into organic molecules are highly sought after. Herein, a direct C−H imidation under gold(I) chloride catalysis has been developed with N‐fluorobenzenesulfonimide as the imine source. The choice of ligand plays an important role where 2,2′‐biquinoline was found to be most efficient. Various polycyclic aromatic hydrocarbons were directly imidated under the newly established protocol.

Interfacial Synergy of PtPd Nanoparticles Dispersed on Amine-Modified ZrSBA-15 in Catalytic Dehydrogenation of Ammonia Borane and Reduction of p-Nitrophenol

In this work, a series of amine-modified ZrSBA-15-supported PtPd bimetallic catalysts with different Pt/Pd ratios were prepared and characterized by a variety of means. Introducing amino groups on the surface of ZrSBA-15 is beneficial for achieving high dispersion of PtPd nanoparticles (NPs) and can effectively prevent the overgrowth of PtPd NPs during the preparation process. The resulting hybrid catalysts exhibit very high catalytic activity and stability for H2 generation from aqueous ammonia borane (AB) and can also efficiently catalyze the reduction of p-nitrophenol to p-aminophenol using AB as the hydrogen source. Among them, the catalyst with the Pt/Pd ratio of 85/15 shows the highest activity for AB dehydrogenation under ambient condition, whereas the catalyst with the Pt/Pd ratio of 50/50 exhibits the highest efficiency for the reduction of p-nitrophenol with AB. These results suggest that highly efficient interface active sites could be constructed by optimizing the composition of bimetallic PtP...

Anti-aging behavior of amino-containing co-condensed nanosilica in polyethylene

Physical loss of stabilizers by migration and extraction accelerates the degradation of polymer materials. In this work, amino-containing nanosilica with anti-aging properties was prepared simply by the co-condensation of tetraethoxysilane and N-(2-aminoethyl)-3-aminoproply-trimethoxysilane (AEAPS). AEAPS was used to introduce amino groups into silica nanoparticles and to act as a catalyst in this process. The co-condensed nanosilica (CCS) showed agglomerate structure similar to the typical fumed nanosilica (FS). The amino groups were distributed both on the surface and inside the nanoparticles. HDPE/CCS and HDPE/FS composites were prepared by melt blending. Thermogravimetric analysis and oxidative induction time showed that CCS has effectively improved the thermo-oxidative stability of HDPE. In the long-term accelerated thermo-oxidative aging and UV aging tests, HDPE/CCS composite showed superior stability to neat HDPE and HDPE/FS composite. The results of infrared spectroscopy and electron paramagnetic resonance suggested that the HDPE/CCS composite manifested a special degradation mechanism involving the nucleophilic addition of amino groups to carbonyl species as well as the oxidation of amino groups on CCS by peroxides. The amino groups on CCS consumed carbonyl species and peroxides, and generated hydroxylamines and nitroxide radicals which were able to eliminate free radicals, thus restrained the degradation of HDPE.

Synthesis of Novel Amino Lactose and Evaluation of Its Antioxidant Property

In order to improve the bioactivity of lactose, a novel lactose derivative is designed and synthesized by introducing an amino group to the C‐6 of lactose. The in vitro antioxidant activities of synthesized lactose derivatives are assessed. It shows better scavenging activity against hydrogen peroxide (IC50 &lt; 0.1 mg mL−1), hydroxyl radicals (IC50 0.55 mg mL−1), and DPPH radicals (IC50 0.37 mg mL−1) than lactose. Based on this data, it is reasonable to propose that the introduction of amino group through chemical modification is significant to enhance the free antioxidant activity of lactose. This derivatization strategy might provide an effective tool to broaden utilization of lactose.

FURAN RING TRANSFORMATION AS KEY STAGE IN THE SYNTHESIS OF 5 H ,12 H -BENZO[4,5]IMIDAZO[1,2- a ]PYRROLO[1,2- d ]PYRAZINES

We report the first synthesis of new condensed benzimidazole derivatives – 5H,12H-benzo[4,5]imidazo[1,2-a]pyrrolo[1,2-d]pyrazines, based on furan ring transformation in 1-[(5-alkylfuran-2-yl)methyl]- 2-(chloromethyl)benzimidazoles. Two routes are presented for the formation of pyrrolopyrazine system, with different order of steps for the introduction of amino group and opening of the furan ring.

Planar Is Better: Monodisperse Three-Layered MoS2 Quantum Dots as Fluorescent Reporters for 2,4,6-Trinitrotoluene Sensing in Environmental Water and Luggage Cases.

In this study, we present a simple but effective fluorescent system for highly sensitive and versatile sensing of 2,4,6-trinitrotoluene (TNT) using few layered planar MoS2 quantum dots (QDs) as reporters. Excitation-independent emitting MoS2 QDs were first fabricated by using the proposed ultrasonic-hydrothermal-based top-down method assisted by carbon-free hydroxylamine hydrochloride. The obtained pristine MoS2 QDs were then modified with cysteine for introducing amino groups as TNT binding sites. The as-prepared MoS2 QDs possess a planar structure, which can more adequately interact with flat aromatic TNT molecules due to π-π attraction and decreased steric effects, compared with traditional spherical/quasi-spherical QDs. As a result, they exhibit extremely high sensitivity for TNT sensing (1 nM and 2 ng for solution and substrate assay, respectively). The common ions containing in environmental water samples do not interfere with the sensing. Furthermore, the QDs-decorated test paper shows an instantaneous (within 1 min) response to trace amounts of deposited TNT, and the fluorescence quenching can even be well-visualized by the naked eye. Because of favorable analytical performances, the proposed MoS2 QDs-based TNT sensing system has potential applications in both environmental water monitoring and security screening.