Role Of Different Functional Groups Research Articles

Green synthesis and characterization of silver nanoparticles using fructose

The green synthesis of nanoparticles is an important branch and a relatively new emerging field in nanotechnology which is easy, environmentally friendly, cost effective, and economically efficient in comparison with the chemical and physical methods. In the present work, for the first time, green synthesis of silver nanoparticles (AgNPs) was carried out by using fructose solution as a reducing agent at room temperature. The silver nanoparticles were characterized by UV-Vis, FTIR, XRD, and TEM analysis. The UV-Vis spectral studies confirmed the surface plasmon resonance of the green synthesized silver nanoparticles. The role of different functional groups in formation of the AgNps was shown by FTIR. X-ray diffraction results confirmed the formation of the the AgNPs and TEM results indicated that the average particle size of the silver nanoparticles was 13.24±8.591 nm.

Cutaneous neurturin overexpression alters mechanical, thermal, and cold responsiveness in physiologically identified primary afferents.

Neurotrophic factors play an important role in the regulation of functional properties of sensory neurons under normal and pathological conditions. The GDNF family member neurturin is one such factor that has been linked to modulating responsiveness to peripheral stimuli. Neurturin binds to the GFRα2 receptor, a receptor found primarily in isolectin B4-expressing polymodal cutaneous nociceptors. Previous work has shown that knockout of GFRα2 alters heat, but not mechanical, responses in dissociated sensory neurons and reduces pain-related behaviors during the second phase of the formalin test. Research has also shown that overexpression of neurturin in basal keratinocytes increases behavioral responsiveness to mechanical stimulation and innocuous cooling of the skin without affecting noxious heat responses. Here we directly examined the impact of neurturin overexpression on cutaneous afferent function. We compared physiological responses of individual sensory neurons to mechanical and thermal stimulation of the skin, using an ex vivo skin-nerve-dorsal root ganglion-spinal cord preparation produced from neurturin-overexpressing (NRTN/OE) mice and wild-type littermate controls. We found that neurturin overexpression increases responsiveness to innocuous mechanical stimuli in A-fiber nociceptors, alters thermal responses in the polymodal subpopulation of C-fiber sensory neurons, and changes the relative numbers of mechanically sensitive but thermally insensitive C-fiber afferents. These results demonstrate the potential roles of different functional groups of sensory neurons in the behavioral changes observed in mice overexpressing cutaneous neurturin and highlight the importance of neurturin in regulating cutaneous afferent response properties.NEW & NOTEWORTHY GDNF family neurotrophic factors regulate the development and function of primary sensory neurons. Of these, neurturin has been shown to modulate mechanical and cooling sensitivity behaviorally. Here we show that overexpression of neurturin in basal keratinocytes regulates mechanical responsiveness in A-fiber primary sensory neurons while increasing the overall numbers of cold-sensing units. Results demonstrate a crucial role for cutaneous neurturin in modulating responsiveness to peripheral stimuli at the level of the primary afferent.

Adsorption of phenols from contaminated water through titania-silica mixed imidazolium based ionic liquid: Equilibrium, kinetic and thermodynamic modeling studies

ABSTRACTThe present study describes the synthesis and characterization of titania-silica mixed imidazolium based ionic liquid (Ti-Si-IL) as well as evaluation of its adsorption behavior towards the 2,4-dinitrophenol (2,4-DNP) and 2,4,6-trichlorophenol (2,4,6-TCP). Synthesized Ti-Si-IL adsorbent was characterized by Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), BET surface area Brunauer-Emmett-Teller (BET), thermogravimetric analysis (TGA) and elemental analysis (CHN). The adsorption of 2,4-DNP and 2,4,6-TCP on Ti-Si-IL was investigated systematically by evaluating the effects of adsorbent dosage, initial pH, contact time and temperature. Satisfactory adsorption 95% and 65% for 2,4-DNP and 2,4,6-TCP was observed at pH 4 and 6, respectively. The kinetic results for 2,4-DNP and 2,4,6-TCP on Ti-Si-IL indicated that the kinetic data follows pseudo-second-order model (R2 = 0.9985 and 0.9750, respectively). Adsorption isotherms were fitted well by the Langmuir model for 2,4-DNP (qm = 44.64 mg g−1 at 318 K) and Freundlich model for 2,4,6-TCP (KF = 0.63 mg g−1 at 318 K). The +ΔH° and -ΔG° values demonstrated that the adsorption of 2,4-DNP was endothermic and spontaneous in nature. While the -ΔH° and +ΔG° values for 2,4,6-TCP adsorption demonstrated exothermic and comparatively nonspontaneous. During the removal process, the role of different functional groups, cyclic structure was monitored and found that the ionic property as well as π-π interactions of host molecules played important role in the extent of adsorption.

Plasma Catalytic Synthesis of Ammonia Using Functionalized-Carbon Coatings in an Atmospheric-Pressure Non-equilibrium Discharge

We investigate the synthesis of ammonia in a non-equilibrium atmospheric-pressure plasma using functionalized-nanodiamond and diamond-like-carbon coatings on α-Al2O3 spheres as catalysts. Oxygenated nanodiamonds were found to increase the production yield of ammonia, while hydrogenated nanodiamonds decreased the yield. Neither type of nanodiamond affected the plasma properties significantly. Using diffuse-reflectance FT-IR and XPS, the role of different functional groups on the catalyst surface was investigated. Evidence is presented that the carbonyl group is associated with an efficient surface adsorption and desorption of hydrogen in ammonia synthesis on the surface of the nanodiamonds, and an increased production of ammonia. Conformal diamond-like-carbon coatings, deposited by plasma-enhanced chemical vapour deposition, led to a plasma with a higher electron density, and increased the production of ammonia.

Insight into the Mechanism of Decontamination and Disinfection at the Functionalized Carbon Nanotube–Polymer Interfaces

The role of different functional groups and the nature of the functional group on multiwalled carbon nanotube (MWCNT) surface were thoroughly studied for silver nanoparticles (AgNPs) loading and on the mechanism of decontamination and disinfection. The surfactant free method for grafting of AgNPs on MWCNT surface followed by vacuum annealing was adapted to enhance the interfacial interactions of nanomaterials with bacteria. The best performing functionalized MWCNT was selected for the fabrication of functional composite membrane for further insight into the interfacial interaction of polymer–nanomaterials. It has been shown that at an optimized weight percentage loading of functionalized MWCNTs, nanotube scaffolds were generated inside the pores of polysulfone membrane to sieve out toxic metal ions and bacteria by physical and chemical elimination without compromising the flux rate of filtration. The structure property relationship of the nanocomposite membrane has been thoroughly evaluated by the morphological, surface area, and contact angle measurement studies. The modified surface of MWCNTs by Ag nanoparticles and polar functional groups placed on the pores of the membrane was thus further exposed for interfacial interaction with the decontaminated and disinfected water, which in turn enhances the efficiency of filtration.

Synthesis, characterization and biocompatibility of silver nanoparticles synthesized from Nigella sativa leaf extract in comparison with chemical silver nanoparticles

Despite the development potential in the field of nanotechnology, there is a concern about possible effects of nanoparticles on the environment and human health. In this study, silver nanoparticles (AgNPs) were synthesized by ‘green’ and ‘chemical’ methods. In the wet-chemistry method, sodium borohydrate, sodium citrate and silver nitrate were used as raw materials. Leaf extract of Nigella sativa was used as reducing as well as capping agent to reduce silver nitrate in the green synthesis method. In addition, toxic responses of both synthesized AgNPs were monitored on bone-building stem cells of mice as well as seed germination and seedling growth of six different plants (Lolium, wheat, bean and common vetch, lettuce and canola). In both synthesis methods, the colorless reaction mixtures turned brown and UV–visible spectra confirmed the presence of silver nanoparticles. Scanning electron microscope (SEM) observations revealed the predominance of silver nanosized crystallites and fourier transform infra-red spectroscopy (FTIR) indicated the role of different functional groups in the synthetic process. MTT assay showed cell viability of bone-building stem cells of mice was further in the green AgNPs synthesized using black cumin extract than chemical AgNPs. IC50 (inhibitory concentrations) values for seed germination, root and shoot length for 6 plants in green AgNPs exposures were higher than the chemical AgNPs. These results suggest that cytotoxicity and phytotoxicity of the green synthesized AgNPs were significantly less than wet-chemistry synthesized ones. This study indicated an economical, simple and efficient ecofriendly technique using leaves of N. sativa for synthesis of AgNPs and confirmed that green AgNPs are safer than chemically-synthesized AgNPs.

Biogenic silver nanoparticles: efficient and effective antifungal agents

Biogenic synthesis of silver nanoparticles (AgNPs) by exploiting various plant materials is an emerging field and considered green nanotechnology as it involves simple, cost effective and ecofriendly procedure. In the present study AgNPs were successfully synthesized using aqueous callus extract of Gymnema sylvestre. The aqueous callus extract treated with 1nM silver nitrate solution resulted in the formation of AgNPs and the surface plasmon resonance (SPR) of the formed AgNPs showed a peak at 437 nm in the UV Visible spectrum. The synthesized AgNPs were characterized using Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), and X-ray diffraction spectroscopy (XRD). FTIR spectra showed the peaks at 3333, 2928, 2361, 1600, 1357 and 1028 cm−1 which revealed the role of different functional groups possibly involved in the synthesis and stabilization of AgNPs. TEM micrograph clearly revealed the size of the AgNPs to be in the range of 3–30 nm with spherical shape and poly-dispersed nature; it is further confirmed by Particle size analysis that the stability of AgNPs is due its high negative Zeta potential (−36.1 mV). XRD pattern revealed the crystal nature of the AgNPs by showing the braggs peaks corresponding to (111), (200), (220) and (311) planes of face-centered cubic crystal phase of silver. Selected area electron diffraction pattern showed diffraction rings and confirmed the crystalline nature of synthesized AgNPs. The synthesized AgNPs exhibited effective antifungal activity against Candida albicans, Candida nonalbicans and Candida tropicalis.

Synthesis of silver nanoparticles using seed exudates of Sinapis arvensis as a novel bioresource, and evaluation of their antifungal activity

In general, silver nanoparticles (AgNPs) are particles of silver with a size less than 100 nm. In recent years, synthesis of nanoparticles using plant extract has gained much interest in nanobiotechnology. In this concern, this study investigates green synthesis of AgNPs from silver nitrate using Sinapis arvensis as a novel bioresource of cost-effective nonhazardous reducing and stabilizing compounds. A stock solution of silver nitrate (0.1 M) was prepared. Different concentrations of silver nitrate (1, 2.5, 4, and 5 mM) were prepared from the above solution, then added to 5 mL of S. arvensis seed exudates. The mixtures were kept in 25°C. The synthesis of AgNPs was confirmed by the change in mixtures color from light yellow to brown. The antifungal activity of synthesized AgNPs was investigated in vitro. The resulting AgNPs were characterized by UV-vis spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR). Formation of the AgNPs was confirmed by the change in mixture color from light yellow to brown and maximum absorption at 412 nm due to surface plasmon resonance of AgNPs. The role of different functional groups in the formation of AgNPs was shown by FTIR. X-ray diffraction was shown that the AgNPs formed in our experiments were in the form of nanocrystal, and TEM analysis showed spherical particles with an average size of 14 nm. Our measurements indicated that S. arvensis seed exudates can mediate facile and eco-friendly biosynthesis of colloidal-spherical AgNPs with a size range of 1 to 35 nm. The synthesized AgNPs showed significance antifungal activity against Neofusicoccum parvum cultures. The AgNPs were synthesized using a biological source. This synthesis method is nontoxic, eco-friendly, and a low-cost technology for the large-scale production. The AgNPs can be used as a new generation of antifungal agents.

One step synthesis of Bi@Bi2O3@carboxylate-rich carbon spheres with enhanced photocatalytic performance

Bi@Bi2O3@carboxylate-rich carbon core-shell nanosturctures (Bi@Bi2O3@CRCSs) have been synthesized via a one-step method. The core–shell nanosturctures of the as-prepared samples were confirmed by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and Raman spectroscopy. The formation of Bi@Bi2O3@CRCSs core–shell nanosturctures should attribute to the synergetic roles of different functional groups of sodium gluconate. Bi@Bi2O3@CRCSs exhibits significant enhanced photocatalytic activity under visible light irradiation (λ>420nm) and shows an O2-dependent feature. According to trapping experiments of radicals and holes, hydroxyl radicals were not the main active oxidative species in the photocatalytic degradation of MB, but O2− are the main active oxidative species.

Acidic dye wastewater treatment onto a marine macroalga, Nizamuddina zanardini (Phylum: Ochrophyta)

Biosorption of Acid Black 1 (AB1) onto brown macroalgae, Nizamuddina zanardinii, was investigated. The effects of different parameters including pH, biomass loading, dye concentration, temperature, and salinity on the biosorption capacity were studies. The result at equilibrium was successfully described by the Freundlich model, and the estimated biosorption capacity was 29.79mg/g. The kinetic of biosorption at different agitation speeds (70–180rpm) and particle sizes (56–500μm) were evaluated by pseudo-second-order, pseudo-first-order, and intraparticle diffusion kinetic models. The results showed that the pseudo-second-order model could be used as a successful model for the biosorption kinetics. Thermodynamics of sorption was investigated at different temperatures from 283 to 313K. The negative values of Gibbs free energy, ΔG0, and positive value of enthalpy, ΔH0, confirm the possibility of the biosorption process and the spontaneous nature of the biosorption. A decrease in particle size of N. zanardinii biomass increased AB1 biosorption capacity. Furthermore, addition of NaCl (0–40g/L) resulted in minor improvement in the dye biosorption. Role of different functional groups on the surface of biomass for biosorption of AB1 was investigated using FTIR.

Spectroscopic study on water diffusion in poly(lactic acid) film

The diffusion of water in biocompatible semicrystalline poly(lactic acid) (PLA) is investigated using time-resolved ATR-FTIR. There are three different states of water molecules diffusing into the film. Using a 2D correlation analysis, the diffusion process and the role of different functional groups on diffusion is obtained. First, the moderately strongly bound water forms a hydrogen bond with –CO. Then, the water diffuses into free volume (microvoids) and strong hydrogen bonds are formed between two –CO groups and water. The conformations of semicrystalline PLA change during the diffusion process and recover after re-drying. In addition, water first interacts with amorphous segments and then interacts with crystalline segments.

Insights into conformational and packing features in a series of aryl substituted ethyl-6-methyl-4-phenyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylates

The supramolecular structures of eight aryl protected ethyl-6-methyl-4-phenyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylates have been analyzed to determine the role of different functional groups on the molecular geometry, conformational characteristics and the packing of these molecules in the crystal lattice. Out of these the parafluoro substituted compound on the aryl ring exhibits conformational polymorphism, due to the different conformation of the ester moiety. This behaviour has been characterized using both powder and single-crystal X-ray diffraction, optical microscopy and differential scanning calorimetry performed on both these polymorphs. The compounds pack via the cooperative interplay of strong N–H⋯OC intermolecular dimers and chains forming a sheet like structure. In addition, weak C–H⋯OC and C–H⋯π interactions impart additional stability to the crystal packing.

Biosorption of mercury and lead by dried Aspergillus niger Tiegh. isolated from estuarine sediments

The sorption of Hg and Pb from mono‐metal and bi‐metal solution under different concentrations (20ppm–80ppm) was studied using dried Aspergillus niger biomass. The biosorption of Hg and Pb from the mono‐metal solution was found to be much better than from the bi‐metal solution. The maximum sorption of heavy metals was observed at pH 5–6 and at temperature 25°C–26°C. Biosorption of heavy metals from mono‐metal and bi‐metal solutions followed the Langmuir and Freundlich isotherm. The role of different functional groups like amine, hydroxyl, carboxyl and the phosphate group was confirmed by FTIR. The adsorption of metal ions on the biomass surface and the possible ion exchange mechanism was confirmed using SEM‐EDAX studies. A. niger can be used as a good biosorption agent for removing Hg and Pb from aqueous solution when present individually or in combination.

Banana peel extract mediated novel route for the synthesis of silver nanoparticles

Bio-inspired silver nanoparticles were synthesized with the aid of a novel, non-toxic, eco-friendly biological material namely, banana peel extract (BPE). Boiled, crushed, acetone precipitated, air-dried peel powder was used for reducing silver nitrate. Silver nanoparticles were formed when the reaction conditions were altered with respect to pH, BPE content, concentration of silver nitrate and incubation temperature. The colorless reaction mixtures turned brown and displayed UV–visible spectra characteristic of silver nanoparticles. Scanning electron microscope (SEM) observations revealed the predominance of silver nanosized crystallites after short incubation periods. When the reaction mixtures were incubated for 15 days, some micro-aggregates were also observed. Energy dispersive spectrometer (EDS) studies and X-ray diffraction analysis confirmed the presence of silver nanoparticles. Fourier transform infra-red spectroscopy (FTIR) indicated the role of different functional groups (carboxyl, amine and hydroxyl) in the synthetic process. These silver nanoparticles displayed antimicrobial activity against fungal as well as bacterial cultures.

Design, synthesis, and urease inhibition studies of a series of 4-amino-5-aryl-3H-1,2,4-triazole-3-thiones

A series of 4-amino-5-aryl-3H-1,2,4-triazole-3-thiones was synthesized by reaction of aryl hydrazides with CS2 and hydrazine hydrate. The synthesized compounds were characterized by spectroanalytical techniques, and their urease inhibition activity was evaluated using jack bean urease. All but one of the synthesized compounds were active, and two of them were found to be more potent than the standard, with 50% inhibition concentration (IC 50) values of 17.5 ± 0.52 and 4.3 ± 0.169 μM, respectively (standard IC 50 = 21.0 ± 0.11 μM). Tentative statements regarding the role of different functional groups in binding to the enzyme active site are also presented.

Characteristics and mechanisms of Cu(II) biosorption by disintegrated aerobic granules

Disintegrated aerobic granules (DAG) as an effective biosorbent had great potential to remove Cu(II) from aqueous solution. The effects of solution pH value, contact time, initial Cu(II) concentration on the biosorption were investigated. Kinetic studies indicate that pseudo-second-order model with correlation coefficients of 0.9999 best fits the Cu(II) biosorption process. Investigation of the biosorption mechanisms shows that Cu(II) biosorption is associated with a significant release of Ca(II). The adsorption capacity of extracted extracellular polymeric substances (EPS) was 2.34 times as much as that of pristine DAG, indicating the significant role of EPS in adsorption. In order to determine the role of different functional groups, DAG was chemically modified to block specific functional groups and was then used in the adsorption of Cu(II). The anionic carboxyl group, was identified as the key binding site for the cationic Cu(II). Results reveal that ion exchange is the most important biosorption mechanism but other mechanisms to some extent like electrostatic interaction, involving in functional groups, also play a part.

English

Silver nanoparticles (Ag NPs) have been synthesized by a facile green method, in which the nanoparticles are yielded in just a few minutes with long-term stability. Silver ions are reduced by means of Abrus precatorius leaf extract (LE), which acts as both reductant and stabilizer concurrently for Ag NPs preparation. The bio-reduced Ag NPs were appropriately characterized. The colorless reaction mixture turned yellow and displayed UV–Vis spectra with surface plasmon resonance at 420 nm typical for Ag NPs. The crystalline nature of NPs was evidenced by both XRD and SAED patterns. The results demonstrate the formation of crystalline Ag NPs with fcc structure having an average crystallite size of 12 nm from XRD profile. Obtained Ag NPs exhibited photoluminescence with Ex of 370 nm. Fourier infrared spectroscopy (FTIR) indicated the role of different functional groups in the Ag NPs formation. Antimicrobial activity was carried out against different test pathogens, in which more inhibitory activity was showed towards Pseudomonas spp. and Penicillium spp. with respect to antibacterial and antifungal properties.

Adsorption of rhodamine B on Rhizopus oryzae: Role of functional groups and cell wall components

The role of different functional groups (i.e. amino, carboxyl, hydroxyl as well as phosphate) and cell wall components (such as chitin, chitosan, glucan and phosphomannan) of Rhizopus oryzae on adsorption of rhodamine B is described. The functional groups were chemically modified to determine their contribution in the present adsorption process. Fourier transformed infrared spectroscopic (FTIR) study was used to characterize the modification of the functional groups due to chemical treatments. Carboxyl and amino groups were identified as most important moieties involved in the binding process. Different cell wall components were also isolated from the cell wall to explore their role involved in the binding process. Phosphomannan fraction adsorbed higher amounts of rhodamine B compared to the other cell wall components. Fluorescence microscopic images also supported the differential adsorption capacity of the various cell wall components.

Role of a tRNA Base Modification and Its Precursors in Frameshifting in Eukaryotes

Little is known about the role of specific base modifications of transfer RNAs. Wyosine bases are tRNA(Phe)-specific modifications that are distinguished by differentiated, lateral side chains and base methylations appended to the core ring structure of a universally conserved G37, adjacent to the anticodon of Phe tRNAs. Based on previous data, we hypothesized that this modification was needed for -1 frameshifting. Using a reporter system incorporating a SCV-LA yeast virus slippery site for detecting -1 frameshifts in vivo, yeast strains were created that enabled chemical-genetic dissection of the role of different functional groups of wyebutosine that are added in a three-step post-transcriptional set of reactions. With this system, hypomodification increased Phe-specific frameshifting, with incremental changes in frameshift efficiency after specific intermediates in the progression of wyebutosine synthesis. These data combined with investigations of wild-type and hypomodified tRNA binding to ribosomes suggest that frameshift efficiency is kinetically and not thermodynamically controlled. The progressive nature of frameshift efficiency with the stage of modification is consistent with a stepwise evolution and tuning of frameshift potential. The stepwise tuning of frameshift efficiency could explain why tRNA(Phe) in some eukaryotes is not fully modified but, rather, hypomodified to capture a specific frameshift potential.

Structural and active site modification studies implicate Glu, Trp and Arg in the activity of xylanase from alkalophilic Bacillus sp. (NCL 87-6-10)

Structural studies and residue modification using group specific reagents were used to ascertain the role of different functional groups in xylanase from alkalophilic Bacillus sp. (NCL 87-6-10). Treatment with N-bromosuccinimide resulted in fast enzyme inactivation. Reaction with Woodward's reagent K resulted in initial fast followed by slower inactivation. In both cases enzyme was protected against inactivation by the substrate, xylan. The reaction of the enzyme with phenylglyoxal has revealed one essential arginine residue at the active site. The three-dimensional structural analysis of the xylanase at 2.8 Å resolution also implicates involvement of Trp, and Arg residues and carboxylate groups in the binding of substrate and in the catalysis of xylanase.