Amide Functional Groups Research Articles

Adenine-mediated amide-containing metal-organic framework toward one-step ethylene purification from a ternary mixture

Simultaneous removal of acetylene (C2H2) and ethane (C2H6) from a ternary gas mixture of acetylene/ethylene/ethane via a one-step process to achieve high purity of ethylene (C2H4) is challenging but highly desirable. Herein, an amide-containing adenine-mediated rod metal-organic framework (MOF) of 1 was solvothermally constructed by means of mixed-linker approach. Structural analysis illustrates that 1 displays 1D microporous channels and features open metal site-free concomitant with uncoordinated carboxylate oxygen atoms and amide functional groups decorated interior pore walls. Interestingly, both single-component gas adsorption and ideal adsorbed solution theory (IAST) prediction reveal that 1 is C2H2 and C2H6 selective, which were eventually confirmed by dynamic column breakthrough experiments through not only binary gas mixtures of C2H2/C2H4 and C2H6/C2H4, but also a ternary mixture of C2H2/C2H4/C2H6 to validate one-step ethylene purification.

Sustainable amidation through acceptorless dehydrogenative coupling by pincer-type catalysts: recent advances

Abstract The amide functional group is ubiquitous in living organisms, and is of particular importance in bioactive compounds and pharmaceuticals. Because of the prevalence and significance of the amide bond, considerable efforts have been invested throughout the years in developing new synthetic methodologies for its formation. Nevertheless, amide synthesis still largely relies on variants of the traditional condensation of carboxylic acids and amines, mediated by stoichiometric coupling reagents. This poses a sustainability challenge, since such reactions suffer from unfavorable atom and step economies, involve harmful chemicals and produce chemical waste. Hence, establishing sustainable approaches to amide synthesis is of great importance. Over the last two decades, we have developed homogeneous catalytic reactions for sustainable synthetic transformations, primarily based on transition metal complexes of pincer ligands. A considerable portion of these efforts has been devoted to acceptorless dehydrogenative coupling, including that of alcohols and amines through ruthenium-catalyzed reactions. These latter processes generate amides without resorting to coupling reagents and typically produce no waste, with their only byproduct being H2 gas, which is itself a valuable resource. In the present review, we chronicle our progress in this area of research since 2014. This includes the use of water and ammonia as amidation reagents, expanding the scope of amidation substrates and target amides, achieving milder reaction conditions, development of amidation-based liquid organic hydrogen carrier systems, and introduction of manganese-based catalysts.

Structural and Functional Characterization of Exopolysaccharide Produced by a Novel Isolate Bacillus sp. EPS003.

An exopolysaccharide (EPS)-producing soil bacterium was isolated and characterized using 16S rRNA as Bacillus sp. EPS003. EPS was precipitated using ethanol and % composition of total carbohydrate, and protein was determined. Monosaccharide composition was identified using thin layer chromatography (TLC), and it was found to be a levan. Fourier transform infrared (FTIR) spectrum revealed the peaks for carboxyl, hydroxyl, and amide functional groups. 1H nuclear magnetic resonance (NMR) spectrum further confirmed the presence of fructose monomer. Field emission scanning electron microscopic images (FE-SEM) revealed porous and amorphous characteristics of EPS which was further confirmed with broad peaks in X-ray diffraction (XRD) spectrum. Elemental composition was determined using energy-dispersive X-ray analysis (EDAX). Thermogravimetric analysis (TGA) of EPS resulted in a residual mass of 33.81% at 548°C indicating high thermal stability. In addition, solubility index and water-holding capacity of EPS were found to be 56% and 264%, respectively, making EPS suitable for various applications. Further, antioxidant potential of EPS was studied using hydroxyl and DPPH radical scavenging assays. In vitro cytotoxicity assessment using L929 cells and SK-MEL-3 cell lines clearly indicated that the EPS produced by the novel isolate Bacillus sp. EPS003 could serve as a potential anticancer agent.

Synthesis and Biological Evaluation of 3-Amidoquinuclidine Quaternary Ammonium Compounds as New Soft Antibacterial Agents.

Quaternary ammonium compounds (QACs) are among the most effective antimicrobial agents that have been used for more than a century. However, due to the growing trend of bacterial resistance and high toxicity of QACs, research in this field remains a pressing matter. Recent studies of the structure-activity relationship suggest that the introduction of the amide functional group into QAC structures results in soft variants that retain their antimicrobial properties while opening the possibility of fine-tuned activity regulation. Here, we report the synthesis and structure-function study of three structurally distinct series of naturally derived soft QACs. The obtained 3-amidoquinuclidine QACs showed a broad range of antibacterial activities related to the hydrophobic-hydrophilic balance of the QAC structures. All three series yielded candidates with minimal inhibitory concentrations (MIC) in the single-digit μM range. Time-resolved growth analysis revealed subtle differences in the antibacterial activity of the selected candidates. The versatile MIC values were recorded in different nutrient media, suggesting that the media composition may have a dramatic impact on the antibacterial potential. The new QACs were found to have excellent potential to suppress bacterial biofilm formation while exhibiting low ability to induce bacterial resistance. In addition, the selected candidates were found to be less toxic than commercially available QACs and proved to be potential substrates for protease degradation. These data suggest that 3-amidoquinuclidine QACs could be considered as novel antimicrobial agents that pose a low threat to ecosystems and human health.

Novel montmorillonite nanosheets-based hydrogel beads with high adsorption performance and structural strength for removal of dyes and heavy metals

A series of high-performance montmorillonite nanosheets (MMTNS)-based hydrogel beads (HG-Bs) are prepared with different amounts of MMTNS, acrylic acid, acrylamide, sodium alginate and polyvinyl alcohol. MMTNS can significantly enhance the adsorption performance and structural strength, showing porous structure, good reusability, and high adsorption capacity of 564.97 mg/g for methylene blue. Moreover, FTIR, EDS and XPS measurements indicate that methylene blue is adsorbed by HG-Bs mainly through the adsorption between methylene blue and carboxyl, amide functional groups in HG-Bs, and the cation exchange. HG-Bs also has good adsorption capacity of 130.3 mg/g for Cu2+ and 155.7 mg/g for Cd2+.

Elucidating antibacterial activity of heteroleptic triarylbismuthanes and synthesis of amide derivatives through activated ester intermediate

Novel heteroleptic triarylbismuthane amides of Ar12Ar2Bi formula where Ar2 contains an amide functional group were tested for antimicrobial activity against various bacterial isolates: S. aureus, methicillin-resistant S. aureus (MRSA), S. pyogenes, E. faecalis and E. coli. The amides were prepared from synthetic intermediate B featuring an N-hydroxysuccinimide ester. The strategy behind B represents a departure from the more common approach of preparing triarylbismuthanes by direct arylation, thus avoiding the risk of dismutation when forming carbon-bismuth bond. Dismutation is essentially a scrambling process, a complication that yields a statistical distribution of heteroleptic and homoleptic products. The amides were prepared in modest to excellent yields (34–95%) and characterized by NMR and mass spectrometry. For antimicrobial testing in this study, additional heteroleptic triarylbismuthanes were included. Although no activity was evident for Gram-negative organisms, several triarylbismuthanes demonstrated significant antimicrobial activity against Gram-positive bacteria, including MRSA, while showing acceptable cytotoxicity profiles in mammalian cells. Presented data suggests that this class of compounds may possess acceptable characteristics to develop antimicrobial therapeutics in the future.

Exceptional preservation of organic matter and iron-organic colloidal mineralization in hydrothermal black smoker-type sulfide mineralization from the Paleoarchean seafloor

Fossil organic matter (OM) in Paleoarchean rocks is an invaluable tracer of ancient life, yet it is often contentious due to low preservation potentials of its original organic molecular characteristics under generally high metamorphic grades. This study reports on exceptionally preserved OM within black smoker-type sulfide mineralizations from the 3.24 billion-years-old Sulphur Springs volcanic-hosted massive sulfide deposit, East Pilbara Terrane, northwestern Australia. Fine scale mineralogical and organic molecular variations – documented by SEM and TEM techniques, Raman and FTIR Spectroscopy, as well as ToF-SIMS analysis – trace the formation of millimetre-scale pyritic hydrothermal orifices. Overmature OM (≳200–250 °C) enriched in aromatic hydrocarbons occurs within earliest formed colloform-banded pyrite that could have precipitated at high temperature upon mixing of hot hydrothermal fluids with cold seawater. In contrast, mature OM (within the catagenesis window; ∼100–150 °C) with lower proportions of aromatic hydrocarbons occasionally occurs alongside pyrite within barite near the inner paleofluid conduits of the hydrothermal orifices. A deposition of this OM generation from cooler fluids enriched in sulfate during waning hydrothermal activity is corroborated by its association with original mineralogy, particularly the occurrence of isolated nanoinclusions of OM within hydrothermal barite away from grain boundaries or fissures and cracks, which renders impossible an origin from post-depositional hydrocarbon migration. When compared to the overmature OM within colloform-banded pyrite, the better-preserved inner OM not only contains less abundant, smaller, and less ordered aromatic hydrocarbons, but also higher amounts of aliphatic molecules with longer chain lengths and higher proportions of carbonyl and amide functional groups. Although the latter characteristics are consistent with contributions by microbial biomass, abiotic origins are equally plausible because hydrothermal processes can produce OM with similar organic molecular attributes. Irrespective of these uncertainties on the ultimate sourcing of OM, common intergrowths of the cooler OM with nanoscopic iron oxides – hematite and lesser magnetite – hint at its hydrothermal deposition from colloidal particles that have been stabilized by iron-organic complexation. Further research is required to ascertain the significance of this process for the hydrothermal cycling and release of organic carbons and bound iron into the Paleoarchean oceans. Collectively, our results show that ancient marine hydrothermal systems can preserve OM with differing degrees of thermal degradation, which allows for insights into its sourcing, cycling, and deposition.

Synthesis and Anti-Leishmanial Properties of Quinolones Derived from Zanthosimuline.

Quinoline derivatives and especially quinolones are considered as privileged structures in medicinal chemistry and are often associated with various biological properties. We recently isolated a series of original monoterpenyl quinolones from the bark of Codiaeum peltatum. As this extract was found to have a significant inhibitory activity against a Leishmania species, we decided to study the anti-leishmanial potential of this type of compound. Leishmaniasis is a serious health problem affecting more than 12 million people in the world. Available drugs cause harmful side effects and resistance for some of them. With the aim of finding anti-leishmanial compounds, we developed a synthetic strategy to access natural quinolones and analogues derived from zanthosimuline. We showed the versatility of this natural compound toward cyclization conditions, leading to various polycyclic quinolone-derived structures. The natural and synthetic compounds were evaluated against amastigote forms of Leishmania infantum. The results obtained confirmed the interest of this family of natural compounds but also revealed promising activities for some intermediates deriving from zanthosimuline. Following the same synthetic strategy, we then prepared 14 new analogues. In this work, we identified two promising molecules with good activities against intramacrophage L. infantum amastigotes without any cytotoxicity. We also showed that slight changes in amide functional groups affect drastically their anti-parasitic activity.

Distinct Hydrogen Bonding Dynamics Underlies the Microheterogeneity in DMF-Water Mixtures.

The hydrogen bonding interaction between the amide functional group and water is fundamental to understanding the liquid-liquid heterogeneity in biological systems. Herein, the structure and dynamics of the N,N-dimethylformamide (DMF)-water mixtures have been investigated by linear and nonlinear IR spectroscopies, using the hydroxyl stretch and extrinsic probe of thiocyanate as local vibrational reporters. According to vibrational relaxation dynamics measurements, the orientational dynamics of water is not directly tied to those of DMF molecules. Wobbling-in-a-cone analysis demonstrates that the water molecules have varying degrees of angular restriction depending on their composition due to the formation of specific water-DMF networks. Because of the preferential solvation by DMF molecules, the rotational dynamics of the extrinsic probe is slowed significantly, and its rotational time constants are correlated to the change of solution viscosity. The unique structural dynamics observed in the DMF-water mixtures is expected to provide important insights into the underlying mechanism of microscopic heterogeneity in binary mixtures.

Maleic and Methacrylic Homopolymers with Pendant Dibutylamine or Dibutylamine Oxide Groups as Kinetic Hydrate Inhibitors.

Kinetic hydrate inhibitors (KHIs) are applied in oil and gas fields to prevent gas hydrate formation, most often in cold subsea flow lines. The main component in industrial KHI formulations is a water-soluble polymer with many amphiphilic groups of which the hydrophilic part is most commonly the amide functional group. In the last decade, we have investigated polyamine oxides as alternatives to polyamides due to the strong hydrogen bonding of the amine oxide group. Here, we report the KHI performance of maleic and methacrylic homopolymers with dialkylamine and dialkylamine oxide pendant groups. Performance screening experiments were conducted under high pressure with a Structure II-forming natural gas mixture in steel rocking cells using the slow (1 °C/h) constant cooling test method. Polymers with dibutylamine groups gave much better KHI performance than polymers with dimethylamine or diethylamine groups. Polyamines formed from polymaleic anhydride reacted with 3-(dibutylamino)-1-propylamine (DBAPA) or 2-(dibutylamino)-ethanol (DBAE) gave good water solubility and good KHI performance, probably due to self-ionization between the dibutylamino and carboxylic acid groups. The lack of self-ionization for the methacryl homopolymers of DBAPA and DBAE explains why these polymers are not water-soluble. Oxidation of the maleic or methacryl polyamines to polyamine oxides gave water-soluble polymers with good compatibility with brines (0.5-7.0 wt % NaCl), but only the DBAPA-based polyamine oxides gave improved KHI performance compared to the polyamines. Poly(3-(dibutylamino oxide)-1-propyl methacrylamide) gave a similar performance to commercial N-vinyl pyrrolidone:N-vinyl caprolactam 1:1 copolymer and without a cloud point in deionized water up to +95 °C.

A 2D mesoporous hydrazone covalent organic framework for selective detection and ultrafast recovery of Au(III) from electronic waste

Developing a material that can simultaneously detect and recover Au(III) is economically desirable. Herein, we constructed a two-dimensional mesoporous fluorescent covalent organic framework named TY-Hz COF by integrating 1,3,6,8-tetra(4-formylphenyl)pyrene (TY) and terephthalic dihydrazide (Hz) into a π-conjugated framework for simultaneous detection and recovery of Au(III). The TY-Hz COF suspension can rapidly (10 s) and sensitively response to Au(III) with electron transfer-induced fluorescence quenching and visual color change from bright yellow to dark green, and the limit of detection is as low as 17 nM. Moreover, TY-Hz COF can capture more than 92 % Au(III) in the solution with extremely fast kinetics (within 2 min) and excellent selectivity with a maximum adsorption capacity of 1008.30 mg g−1. It is worth mentioning that TY-Hz is the first type of COF that achieves Au(III) detection, adsorption and chemical reduction simultaneously. Mechanistic studies reveal that the detection and adsorption behaviors can be attributed to the synergistic effect of reduction, coordination interaction between neutral amide functional groups and Au(III), and hydrogen bonding between protonated amides and AuCl4-. These results suggest that TY-Hz COF shows great potential for Au(III) detection and recovery in electronic waste (e-waste).

Ion rejection performances of functionalized porous graphene nanomembranes for wastewater purification: A molecular dynamics simulation study

Performances of small- and large-pore, porous graphene nanomembranes (PGNMs) (pristine and functionalized by amide, sulfonic acid, thiourea, and carbamate functional groups) for purification of heavy metal ions and nitrate-contaminated wastewater were determined using molecular dynamics (MD) simulation. At the operational conditions of the simulated membrane (150 and 0.1 MPa pressure on the left and right piston sides at 300 K), higher water flow rates were obtained in the functionalized PGNMs possessing large pores, as opposed to the non-functionalized and small-pore ones. Amide-functionalized PGNM provided the highest flow rate (380 and 330 molecules/ns for large and small pores, respectively). Cu2+ and As3+ ions were rejected at a level of 100% in the small-pore PGNMs, while the rejection level of the NO3- ions was about 95%. For large-pore PGNMs, As3+ ions were rejected at a level of 100%, while a few Cu2+ and NO3- ions could pass through the pores with no discernible dependence on the graphene surface chemistry. A radial distribution function (RDF) analysis revealed two hydration radii for all ions interacting with the surrounding water clusters. Overall, graphene surface chemistry modification did not significantly affect the ion rejection performance.

Role of a novel cationic gemini surfactant (CGS) on a one-step sol-gel process and photocatalytic properties of TiO2 powders.

TiO2 nanoparticles were prepared using a sol-gel process in combination with a novel cationic gemini surfactant (CGS) with amide functional groups at low temperatures. Titanium (IV) isopropoxide (TIP) and CGS were used as the starting materials and as effective agents, respectively, to orient the nanoparticles during the sol-gel synthesis. To reveal both the structural and morphological properties of the nanopowders prepared in this work, they were characterized using X-ray diffraction (XRD) analysis, scanning electron microscope (SEM), and Brunauer-Emmett-Teller (BET) surface area apparatus. The pore volume and pore size were calculated using the Barrett-Joyner-Halenda (BJH) model on the desorption branch. The experimental results show that the surface area and average crystallite size of the obtained TiO2 nanopowders vary between 160-203 m2/g and 27-49 nm, respectively. It was observed that the N2 adsorption-desorption isotherms for almost all samples of TiO2-X% CGS (X: mass of CGS) show the typical Type I with a hysteresis loop of H4. The photocatalytic activities of the CGS-modified nanocomposites are evaluated not only by the photocatalytic degradation of methyl orange (MO) but also by the reduction of Cr(VI) as model pollutants in the presence of visible light.

Naphthodipyrrolopyrrole-based Aza-BODIPY dye for N-type organic field-effect transistors

To date, n-type semiconductor designs are less investigated than their p-type counterparts, due to the fact that the charge transport mobility and the stability of the n-type materials are generally lower than those of the p-type ones. Well-defined n-type semiconductors often require low lowest unoccupied molecular orbital (LUMO) levels that facilitate the electron injection from the electrode into the semiconductors. Therefore, it is of significance to explore novel chromophores with strong electron-deficient properties, yet it is still challenging. Herein, a naphthodipyrrolopyrrole-based dimeric aza-boron dipyrromethene (Aza-BODIPY) dye (NDP-AB) is designed and synthesized. The optical studies indicate that NDP-AB presents a blue spectral shift (111 nm) in solution phase compared to the thin film state, while exhibiting a photoluminescence emission quenching. The NDP-AB semiconductor demonstrates strong acceptor properties with a low LUMO energy level of only −4.25 eV, owing to the multi-fluorine atoms, unsaturated nitrogen atoms, as well as the amide functional groups. Moreover, the large conjugation system, highly planar core, along with the large transition dipole on the line that links 2-position with 6-position of the BODIPY core, result in NDP-AB with a strong H-aggregation. As a consequence, the NDP-AB-based semiconductors show a good n-type behavior with an average electron mobility of 0.16 cm2 V−1 s−1. Our work, proposes a strong electron-deficient chromophore that is a promising candidate as building block of organic field-effect transistors. Our design strategy paves the way for the identification of more n-type semiconductor materials with high-performance.

Electronic effect-dependent intramolecular non-covalent interactions on the activity of 4,4-dimethylimidazolidin-2-one pharmacophore-based androgen receptor antagonists.

Because androgen receptor (AR) signalling is important for the development and progression of prostate cancer (PC), AR antagonists are utilized in clinical practices to treat PC and are referred to as androgen deprivation therapy (ADT). However, continued administration of AR antagonists often results in the development of resistance, known as castration-resistant prostate cancer (CRPC). Despite castration, it has been demonstrated that AR signalling continues to be fundamental to tumour growth. In this regard, a series of readily synthesizable 4,4-dimethylimidazolidine-2-one pharmacophore-based AR antagonists (FAR01-FAR11) were designed and synthesized. Androgen-dependent LNCaP PC cell line was used to test the AR-antagonist activity of these compounds in vitro and compared with the U.S. Food and Drug Administration (FDA) approved second-generation enzalutamide. In our previous work, rigid thiohydantoin pharmacophore in enzalutamide is replaced by the flexible 4,4-dimethylimidazolidin-2-one. In order to improve the flexibility further, one methylene group is introduced between the pharmacophore and one of the aromatic ring. Despite the fact that the amide functional group is a crucial characteristic for building AR antagonists, this class of molecules lacks one. FAR06 has the exact same activity as enzalutamide (IC50 : 0.782 μM) with an IC50 value of 0.801 μM among the series of compounds.

A double network conductive gel with robust mechanical properties based on polymerizable deep eutectic solvent

Hydrogels with excellent biocompatibility have become hot topics in the field of flexible electronic wearability. However, high water content and poor mechanical properties limit its application, especially in low temperature environment. We filled the deep eutectic solvent (DES) into the porous structure of polyacrylamide hydrogel (PAAM) by impregnation displacement method. Free radical polymerization was performed in the hydrogel pores using a deep eutectic solvent to form a double-network composite gel with excellent mechanical properties and low temperature resistance. By adjusting the substitution ratio of polyacrylamide hydrogel and deep eutectic solvent, the conductive and mechanical properties of the composite gel were flexibly adjusted. There were a large number of amide and carboxyl functional groups in the composite gel with double network structure, which could form strong hydrogen bond interaction and gave the composite gel excellent mechanical properties (strain up to 1373 %, stress up to 3.14 MPa). In addition, the choline chloride in the deep eutectic solvent provided the gel with good electrical conductivity (∼0.21 ms/cm). Since the water in the composite gel was replaced by a deep eutectic solvent, the gel could resist low temperature (−20 ℃). The large stress-strain gels open up a new way to fabricate organic transparent conductive elastomers for a myriad of future applications in flexible electronics.

Corn oil based cinnamate amide/Fe2O3 nanocomposite anticorrosive coating material

ObjectivesThe efforts are being focused to utilise sustainable resources such as vegetable oils, which are amenable to chemical transformations producing monomers and polymers yielding protective coatings. The present manuscript describes the preparation of nanocomposite coatings from corn oil (CO). MethodsCO was subjected to amidation followed by esterification by cinnamic acid producing CO cinnamate-amide (COCA). COCA was next enriched with Fe2O3 nanoparticles (COCA/ Fe2O3) and crosslinked with phenol formaldehyde to produce polymeric coatings on mild steel panels. ResultsCOCA obtained was rich in functional groups: benzene ring, conjugated with an acrylic group, ester and amide functional group with pendant alkyl chain, and terminal hydroxyl group. The multiple functional groups and nanoparticles offered good adhesion, scratch resistance and flexibility to the resulting nanocomposite coatings. COCA/Fe2O3 coatings showed good physico-mechanical properties and corrosion resistance performance in 3.5 wt% NaCl medium and can be safely used upto 225 °C.

Ag nanoparticles synthesized by Datura metel L. Leaf extract and their charge density distribution, electrochemical and biological performance

The present study investigates the electrochemical performance; charge density distribution, antimicrobial and antifungal activities of green synthesized silver nanoparticles (Ag NPs) using the leaf extract of Datura metel L. UV–vis absorption spectrum shows that highly stable, monodispersed Ag NPs formed at 418 nm. Particle size analysis with zeta potential values 117 nm, − 27.3 mV are implied that hydrodynamic size with negative surface charges. Fourier transforms infrared (FTIR) analysis identified amide functional groups in Datura metel L. responsible for the reduction and stabilization of nanoparticles. Scanning electron microscopy (SEM) analysis showed about the spherical morphology and Energy Dispersive Absorption X-ray (EDAX) spectrum displays the Ag peak at 3.1 KeV with encapsulation of organic trace elements. X-ray Photoelectron Spectroscopy (XPS) analysis exhibit’s Ag 3d, Ag 3p, and Ag 3s chemical state of Ag NPs and the X-ray Diffraction (XRD) pattern confirmed the crystalline nature at 38.1˚ with organometallic phases. The structure factors in the single unit cells are studied in about three, two, and one-dimensional profiles using the Rietveld refinement technique. The complex of atropine with the nanoparticle was modeled using the MOPS method. The formation of the complex is carried out due to the transfer of the electron density of Ag NPs to the atropine molecule, which consists of more electronegative atoms. A charge transfer complex in which the nanoparticle acquires a charge of +0.354 and the atropine – 0.354 is formed. The synthesized Ag NPs exhibited noticeable antimicrobial, antifungal activity with large–diameter inhibition zones against S. pyogenes (12.1 ± 0.66 mm), E. faecalis (11.8 ± 0.33 mm), K. pneumoniae (10.2 ± 0.44 mm), S. flexneri (10.3 ± 0.21 mm), C. albicans (11.3 ± 0.66 mm), and A. fumigatus (10.5 ± 0.33 mm). The green synthesized Ag NPs as prepared electrode exhibits specific capacitance of 825 F/g at the current density of 3 mA/g in 1 M KOH electrolyte solution and cyclic stability retained at about 88.35% even after 5000 cycles with the current density of 5 mA/g. The results showed their effective utilization of green synthesized Ag NPs in biological and electrochemical storage applications.

Biosorption and biomagnetic recovery of La3+ by Magnetospirillum magneticum AMB-1 biomass

Biosorption is a simple, efficient, and eco-friendly method for aqueous waste stream treatment. However, the main drawback is the need for biomass removal after adsorption, which can be expensive and energy intensive. In the present study, biomass from the magnetotactic bacterium Magnetospirillum magneticum AMB-1 is evaluated for trivalent lanthanum (La3+) removal and recovery from an aqueous solution, as this naturally magnetic biomass can be easily separated from solution after adsorption using an external magnet. This is the first report of this common magnetotactic strain utilized for biosorption of a rare earth element. The adsorption capacity is 6.0 ± 0.15 mg La3+/g wet biomass (37.2 ± 1.2 mg La3+/g dry biomass) using 10 g/L AMB-1 wet biomass (1.6 g/L dry basis) in a 100 mg/L La3+ solution at pH 6.0, which is greater than that reported for some other bacterial species. Only a minor decrease in biosorption is observed when the salinity is increased to 1.5 M NaCl, and temperature variations up to 50 °C have little to no impact, suggestive of potential applications for biosorption from saline waste streams. The equilibrium biosorption data best fits the Langmuir isotherm model, and thermodynamic analysis indicates thermodynamically favorable lanthanum binding to AMB-1. Binding of La3+ to the AMB-1 biomass occurs through carboxyl, phosphate, and amide functional groups naturally present in the biomass. AMB-1 biomass can be used for at least five rounds of La3+ adsorption and desorption, as well as the separation and concentration of a mixture of rare earth elements. Rapid adsorption and desorption times of 8 min, as well as a simple magnetic separation, make M. magneticum AMB-1 biomass a promising biosorbent for rare earth metals in aqueous waste streams.

Characterisation of Bovine Amniotic Membrane with Hydroxyapatite Bio-Composite

The fabrication of bio-composite-derived bovine amniotic membrane (BAM) with hydroxyapatite (HAp) is an approach to combining organic and inorganic bio-material to improve the properties of both materials. This research aims to combine, fabricate and characterise the bio-composite of BAM–HA. The combination of bio-composite is made from BAM and HAp in a ratio of 30:70, 35:65, and 40:60. Dried BAM is immersed in saline and then blended until it forms an amniotic slurry with a jelly-like consistency. At this stage, HAp is added so that it can bind to BAM. After the mixture is homogeneous, the freeze-drying process is carried out. After fabrication, all the bio-composites were characterised using Fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and porosity analysis, and biological activity was conducted using fibroblasts. The bio-composite has functional groups of amides I, II, III, A, B, OH, CO32− and PO43− according to the results of the FTIR. The XRD analysis showed the presence of HAP crystals. This functional group and the crystal HAP indicate that these two materials are bound. An SEM examination revealed a variety of porous patterns on the surface area. The bio-composite with BAM and HAp at a ratio of 35:65 has a higher mean pore size of 155.625 µm with mean porosity of 89.23% and can maintain the fibroblast viability of 95.14%. In conclusion, the study successfully combined both bio-materials BAM and HAp, which have potential synergistic effects on soft and hard tissue regeneration. The ratio of 35:65 showed good characteristics and was non-toxic.