Carboxylate Form Research Articles

Study on the functionalization of activated carbon and the effect of binder toward capacitive deionization application

Abstract Capacitive deionization (CDI) is a high-performance and low-cost technology for desalination. Normally, the CDI electrodes are fabricated using a slurry of activated carbon (AC) with a polymeric binder. In this study, AC from coconut shell charcoal was modified in 7% HNO3 solution, which is emphasized by the formation of functional groups on its surface after modification. The isoelectric point (pHIEP) of modified AC is found at 3.02, which confirmed the formation of carboxyl and phenolic hydroxyl groups on the surface. The effect of polyvinyl alcohol (PVA) and polyvinylidene fluoride (PVDF) polymeric binders on characteristics as well as the specific capacitance of the CDI electrodes are investigated. The hydrophilic binder of PVA-based with mesh structure has proven to be promising for salt adsorption ability with the specific capacitance of 47.78 F·g−1, which is higher than that of PVDF binder (17.96 F‧g−1). The composite electrode based on mAC, Gt, and PVA-GA binder has a salt adsorption capacity of 8.9 mg·g−1 and good cyclic stability (retained 94%) after 50 adsorption–desorption cycles at an applied voltage of 1.2 V.

C60 Fullerene Clusters Stabilize the Biologically Inactive Form of Topotecan.

There is a range of experimental proofs that biologically relevant compounds change their activity in the presence of C60 fullerene clusters in aqueous solution, which most frequently act as a nanoplatform for drug delivery. Inspired by this evidence, we made an effort to investigate the interaction of fullerene clusters with the antibiotic topotecan (TPT). This study proceeded in three steps, namely, UV/vis titration to confirm complexation and in vitro assays on proliferating and nonproliferating cells to elucidate the role of C60 fullerene in the putative change in TPT activity. Surprisingly, although the nonproliferating cell assay is consistent with the titration data and confirms complex formation, it contradicted the results of the proliferating cell assay. The latter showed that the mixture of TPT and fullerene affects the cells in the same way as pure TPT, as if there were no fullerenes in solution at all, whereas the action of TPT was expected to be enhanced. We explained this contradiction by the specific stabilization of the biologically inactive carboxylate form of the antibiotic adsorbed in the alkaline shell of large fullerene clusters, which leads to neutralization of the drug delivery function and almost zero net biological effect of the antibiotic in vitro. The practical outcome of the work is that fullerene clusters can be used for the selective delivery of pH-sensitive drug forms.

Microstructural design and mechanical performance of epoxy/carbon nanotube fiber composite

In this paper, carbon nanotube (CNT) fiber is chemically modified through a post-spinning process with an acid treatment and epoxy infiltration. Thermo-gravimetric analysis (TGA), FTIR, and Raman spectroscopy revealed that acid treatment reduced impurities of CNT fibers and induced the formation of carboxylic functional groups on the CNTs surface that positively affect the strength; however, some defects on the surface of the nanotubes were induced that negatively affect the elastic modulus. After the epoxy infiltration procedure, it was revealed that the pores of CNT fiber were filled with epoxy resulting in improved interfacial interaction between CNT bundles either through an interlocking of polymer chains wrapping around the tubes or even by creating covalent bonds between the carboxyl-functionalized nanotubes. Comparing the mechanical performance of epoxy/CNT fibers with and without acid treatment indicated that pre-treatment of the fibers with acid before epoxy infiltration caused a reduction in the final modulus. The modulus of epoxy/CNT fiber reaches 103 N/tex and is about 20% higher than the acid-treated counterpart. Acid treatment prior to epoxy resin infiltration generates functional groups on the CNTs surface that enhance the fiber’s strength through strong reactions between epoxy chains and CNTs. On the other hand, the structural defects on CNTs imposed by acid lead to a reduction in the elastic modulus.

Revealing C-terminal peptide amidation by the use of the survival yield technique

α-amidation of peptide sequences is a common post-translational modification in the living world. Since the majority of these C-terminal amidated peptides are bioactive, there is hence a great interest to identify and characterize them from biological matrices and natural extracts. Regarding conventional separative methods dedicated to peptides (such as HPLC or CE), elution protocols must be carefully optimized hampering straightforward LC-MS analysis of complex samples. From a mass spectrometry point of view, they are difficult to pinpoint owing to the only 1 Da mass difference between the post-translational amidated and the corresponding native carboxylated forms producing overlapping isotopic contributions of both molecular ions. To circumvent this analytical difficulty, usage of energy-resolved tandem mass spectrometry experiments and of the survival yield technique was investigated. Pair of peptides were thus dissociated in positive and negative mode according to the survival yield technique, in MS2 and MS3 experiments, in order to separate them giving a reliable MS/MS methodology to detect such post-translationally modified sequence.

The Impact of Atmospheric Plasma/UV Laser Treatment on the Chemical and Physical Properties of Cotton and Polyester Fabrics

Atmospheric plasma treatment can modify fabric surfaces without affecting their bulk properties. One recently developed, novel variant combines both plasma and UV laser energy sources as a means of energising fibre surfaces. Using this system, the two most commonly used fibres, cotton and polyester, have been studied to assess how respective fabric surfaces were influenced by plasma power dosage, atmosphere composition and the effects of the presence or absence of UV laser (308 nm XeCl) energy. Plasma/UV exposures caused physical and chemical changes on both fabric surfaces, which were characterised using a number of techniques including scanning electron microscopy (SEM), radical scavenging (using 2,2-diphenyl-1-picrylhydrazyl (DPPH)), thermal analysis (TGA/DTG, DSC and DMA), electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS). Other properties studied included wettability and dye uptake. Intermediate radical formation, influenced by plasma power and presence or absence of UV, was key in determining surface changes, especially in the presence of low concentrations of oxygen or carbon dioxide (20%) mixed with either nitrogen or argon. Increased dyeability with methylene blue indicated the formation of carboxyl groups in both exposed cotton and polyester fabrics. In the case of polyester, thermal analysis suggested increased cross-linking had occurred under all conditions.

PRODUCTION OF CELLULOSE NANOCRYSTALS FROM OIL PALM EMPTY FRUIT BUNCH AND PINEAPPLE LEAF FIBRE USING DOUBLE OXIDATION APPROACH

Cellulose nanocrystasl (CNC) were produced from oil palm empty fruit bunch (EFB) and pineapple leaf fibre (PALF) using double oxidation treatment comprising bleaching and ammonium persulfate (APS) treatments. Different techniques were used to characterise the extracted CNC. Fourier transform infrared (FTIR) spectra confirmed the formation of carboxyl group and decreasing fractions of non-cellulosic components. The CNCs from both fibres show a better crystallinity index than the raw fibre, and the CNCs also conform to the crystalline structure of cellulose I. Morphology analysis using transmission electron microscopy (TEM) reveals that the CNCs of EFB and PALF have different shapes and dimensions. Spherical EFB had a 16.33 ± 8.5 nm diameter, while rod-like PALF had 13.07 ± 6.15 nm and 78.67 ± 38.07 nm diameter and length. However, the thermal stability of both CNCs decreased slightly. Hence, the findings indicate that the double oxidation approach using agricultural biomass wastes can work as an alternative route for the preparation of CNCs.

A Cell Trappable Methyl Rhodol-Based Fluorescent Probe for Hydrogen Sulfide Detection.

Hydrogen sulfide is a biologically important molecule and developing chemical tools that enable further investigations into the functions of H2 S is essential. Fluorescent turn-on H2 S probes have been developed for use in cellulo and in vivo, but the membrane permeability of these probes can lead to probe leakage and signal attenuation over time. Here we report a cell trappable fluorescent probe for H2 S, CT-MeRhoAz, which is based on a methylrhodolazide scaffold derivatized with an acetoxymethyl ester group. Prior to ester cleavage, the CT-MeRhoAz probe generates a 2500-fold turn-on response to H2 S, which is enhanced to a 3000-fold response for the carboxylic acid form of the probe. Additionally, the probe is highly selective for H2 S over other biologically relevant sulfur, oxygen, and nitrogen-based analytes. Live cell imaging experiments confirmed the biocompatibility of CT-MeRhoAz and also that it is cell trappable, unlike the parent MeRhoAz scaffold.

Hydrophobic Films Surface Preparation And Its Impact On Wet Cleaning

Keywords: hydrophobic films, drying marks, SiCN, amorphous carbon, chemical oxide growthIntroduction Integrated circuits manufacturing requires use of hydrophobic materials, as low-k films. Maintaining their integrity during wet cleaning is challenging. Indeed, the aqueous liquid film break-up on these surfaces during the cleaning process can result in undesired drying marks defects [1] which can cause open-circuits and be yield killers by blocking proper patterning. Use of dry-cleaning methods instead of wet chemistries can be a solution to avoid drying marks formation. However, while relevant in particle removal they cannot remove chemisorbed defects. Therefore, the use of aqueous solutions cannot be always avoided to clean hydrophobic films. In this case, inducing surface modification of the hydrophobic surface before the aqueous-cleaning step can be a solution. Since drying is carried out after the surface becomes hydrophilic, the occurrence of drying marks can be prevented.In this work we first study how chemical treatments can modify hydrophobic surfaces, so they get a hydrophilic nature. Based on that, we evaluate the interest that can have such step before aqueous wafer cleaning techniques.Experimental and characterizationsSilicon carbon nitrogen (SiCN) and amorphous carbon (a-C) films are deposited by plasma enhanced chemical vapor deposition method on 300mm p-type (011) silicon substrate. The a-C composition is of 65% carbon,35% hydrogen while the SiCN composition is of: 42% Hydrogen, 20% carbon, 14% nitrogen, 24% silicon. They have been obtained with elastic recoil detection analysis, nuclear reaction analysis and Rutherford backscattering spectroscopy. All wet chemical surface preparations have been carried out on spin dry single wafer platforms from SCREEN. Two wet chemistries have been evaluated: Standard Clean 1 (mix of ammonia, hydrogen peroxide and water with a respective volume ratio of 1/2/80, fresh chemistry at 65°C) and ozonated water (20ppm). A treatment with an excimer ultraviolet lamp with a 172nm wavelength has been also done.The reactions between these films and treatments are characterized by AR-XPS and XRR.Artificial contamination of SiCN wafers for particle removal tests has been done by spin-drying using isopropanol containing monodisperse SiO2 particles of 80nm.Results and discussionThe surface preparations of a-C and SiCN films impact the water contact angles, as reported in Figure 1.A-C surface presents a contact angle of 5° with water, after UV or ozonated water treatments, while stays unaltered with the SC1. This difference between the ozonated water and SC1 dispense can be related to the oxidizing power difference as ozonated water features higher redox potential than ammonia. Proposed mechanism of amorphous carbon oxidation by ozone is the breaking of C=C bonds and the formation of carboxyl —COOH groups [2].On the other hand, SiCN contact angle is reduced by SC1, ozonated water and UV (respectively 45, 30 and 5°). AR-XPS characterizations have been used to identify the bonds modification during these treatments. The results lead to the conclusion of an oxidation mechanism for ozonated water, with an oxide layer thickness of less than 5nm (XRR) (Table 1). SiCN bonds oxidation are thermodynamically favored, even though kinetics of these reactions has not been studied (Table 2).The development of a hydrophilic behavior on these surfaces suggests that we avoid watermarks formations. A comparison of SC1 spray cleaning on modified and as deposited SiCN wafers has been carried, to determine the impact of surface modification on particle removal efficiency.Nevertheless, in the specific case of low-k films two potential impacts of these surface modifications also need to be investigated. Indeed, electrical properties of low-k films are key parameters, that is why the consequences of surface modification on them need to be evaluated. And delamination of low-k interfaces is already a failure risk. It would be enhanced by an adhesion strength reduction due to surface energy change. Contact angle measurements and the Fowkes model have been used to deduce the influence of these treatments on surface energy.ConclusionThe cleaning of hydrophobic films is a key challenge for yield benefits. These films are prone to drying marks formation during aqueous cleaning steps. In this work, we study how surface preparation can break non-polar bonds, leading to the development of a hydrophilic surface. Several treatments (UV, SC1 and ozonated water) and materials (a-C, SiCN) have been studied. A comparison of particle removal efficiency with SC1 spray method between as deposited and modified films have been carried out, to quantify the impact of these modifications on wet surface cleaning.

Ecological and Process Aspects of Oxidative Biodegradable Films Production Based on Low Density Polyethylene

Modifying additives impact – pro-oxidants – on low-density polyethylene oxidative degradation under short-term aging conditions in a thermostat with forced convection at 70 °C and ultraviolet irradiation with different exposures (48, 96, 144 h) was studied. It is concluded that for polyethylene films modified with stearates of metals of variable valence, under short-term aging conditions, the formation of aldehydes (1733–1740 cm-1) and carboxyl (1700 cm-1) was observed and accompanied by a sharp decrease in the intensity of absorption bands at 1465–1470 cm-1, which is specific to stretching and bending deformations of CH2 of the polyethylene polymer matrix and indicating the destruction of polymer chains. It is shown that the short-term aging of oxidatively biodegradable polyethylene affects environmental and technological problems associated with the pollutants release, including in particular, formaldehyde and other pollutants.

Oxidized Forms of Olive Oil Secoiridoids: Semisynthesis, Identification and Correlation with Quality Parameters.

Secoiridoids is the prominent chemical class of olive oil polar constituents and are characterized by significant biological properties. They are abundant in different chemical forms and relatively high concentrations compared to other components, while prone to oxidation due to their chemical motif. In recent years, oxidized derivatives of secoiridoids have been reported, either as natural constituents of olive oil or as components which are gradually formed in all stages of its production and storage. The mono-oxidized forms of oleocanthal and oleacein named as the respective acids have been recently isolated from olive oil and unambiguously structurally characterized. Other oxidized forms of elenolic acid or more complex secoiridoids, such as those of oleuropein and ligstroside aglycones are also sporadically mentioned in the literature. No further information is provided since they have not been isolated in pure form in order to be accurately identified. Most of the time, they are generally referred as oxidized forms of the parent compounds and commonly identified based on mass spectrometric data. In the current study, the semi-synthesis of the main oxidized olive oil secoiridoids, i.e., oleocanthalic acid, oleaceinic acid, EDA acid, carboxylic form of elenolic acid, carboxylic form of ligstroside aglycon, and carboxylic form of oleuropein aglycon is described starting from the corresponding aldehydic derivatives, using SeO 2 /H 2 O 2 as oxidative agents. Furthermore, their presence in a number of Greek olive oils was investigated as well, as possible correlation thereof with quality parameters.

Molecular Pathways and Roles for Vitamin K2-7 as a Health-Beneficial Nutraceutical: Challenges and Opportunities.

Vitamin K2-7, also known as menaquinone-7 (MK-7) is a form of vitamin K that has health-beneficial effects in osteoporosis, cardiovascular disease, inflammation, cancer, Alzheimer’s disease, diabetes and peripheral neuropathy. Compared to vitamin K1 (phylloquinone), K2-7 is absorbed more readily and is more bioavailable. Clinical studies have unequivocally demonstrated the utility of vitamin K2-7 supplementation in ameliorating peripheral neuropathy, reducing bone fracture risk and improving cardiovascular health. We examine how undercarboxylated osteocalcin (ucOC) and matrix Gla protein (ucMGP) are converted to carboxylated forms (cOC and cMGP respectively) by K2-7 acting as a cofactor, thus facilitating the deposition of calcium in bones and preventing vascular calcification. K2-7 is beneficial in managing bone loss because it upregulates osteoprotegerin which is a decoy receptor for RANK ligand (RANKL) thus inhibiting bone resorption. We also review the evidence for the health-beneficial outcomes of K2-7 in diabetes, peripheral neuropathy and Alzheimer’s disease. In addition, we discuss the K2-7-mediated suppression of growth in cancer cells via cell-cycle arrest, autophagy and apoptosis. The mechanistic basis for the disease-modulating effects of K2-7 is mediated through various signal transduction pathways such as PI3K/AKT, MAP Kinase, JAK/STAT, NF-κB, etc. Interestingly, K2-7 is also responsible for suppression of proinflammatory mediators such as IL-1α, IL-1β and TNF-α. We elucidate various genes modulated by K2-7 as well as the clinical pharmacometrics of vitamin K2-7 including K2-7-mediated pharmacokinetics/pharmacodynamics (PK/PD). Further, we discuss the current status of clinical trials on K2-7 that shed light on dosing strategies for maximum health benefits. Taken together, this is a synthetic review that delineates the health-beneficial effects of K2-7 in a clinical setting, highlights the molecular basis for these effects, elucidates the clinical pharmacokinetics of K2-7, and underscores the need for K2-7 supplementation in the global diet.

Mass Spectrometry-Based Metabolomics of Phytocannabinoids from Non-Cannabis Plant Origins.

Phytocannabinoids are isoprenylated resorcinyl polyketides produced mostly in glandular trichomes of Cannabis sativa L. These discoveries led to the identification of cannabinoid receptors, which modulate psychotropic and pharmacological reactions and are found primarily in the human central nervous system. As a result of the biogenetic process, aliphatic ketide phytocannabinoids are exclusively found in the cannabis species and have a limited natural distribution, whereas phenethyl-type phytocannabinoids are present in higher plants, liverworts, and fungi. The development of cannabinomics has uncovered evidence of new sources containing various phytocannabinoid derivatives. Phytocannabinoids have been isolated as artifacts from their carboxylated forms (pre-cannabinoids or acidic cannabinoids) from plant sources. In this review, the overview of the phytocannabinoid biosynthesis is presented. Different non-cannabis plant sources are described either from those belonging to the angiosperm species and bryophytes, together with their metabolomic structures. Lastly, we discuss the legal framework for the ingestion of these biological materials which currently receive the attention as a legal high.

Unveiling host–guest–solvent interactions in solution by identifying highly unstable host–guest configurations in thermal non-equilibrium gas phase

We propose a novel scheme of examining the host–guest–solvent interactions in solution from their gas phase structures. By adopting the permethylated β-cyclodextrin (perm β-CD)–protonated L-Lysine non-covalent complex as a prototypical system, we present the infrared multiple photon dissociation (IRMPD) spectrum of the gas phase complex produced by electrospray ionization technique. In order to elucidate the structure of perm β-CD)/LysH+ complex in the gas phase, we carry out quantum chemical calculations to assign the two strong peaks at 3,340 and 3,560 cm−1 in the IRMPD spectrum, finding that the carboxyl forms loose hydrogen bonding with the perm β-CD, whereas the ammonium group of L-Lysine is away from the perm β-CD unit. By simulating the structures of perm β-CD/H+/L-Lysine complex in solution using the supramolecule/continuum model, we find that the extremely unstable gas phase structure corresponds to the most stable conformer in solution.

Chemical and microbiological changes on the surface of microplastic after long term exposition to different concentrations of ammonium in the environment

The increasing production of plastic in the world has resulted in the widespread pollution of the environment with microplastics (MP). MP enter facilities such as wastewater treatment plants or landfills characterized by various ammonium concentrations. The aim of this study was to determine the structure of the microbial community on MP surfaces at various concentrations of ammonium nitrogen, and in particular, to identify microorganisms capable of polyethylene terephthalate (PET) degradation. Moreover, changes in the chemical characteristics of the MP surface resulting from microbial activity were also investigated, and the potential of MP to serve as a vector for pollutants was determined. The tests were carried out in a reactor filled with PET for a period of 260 days. The experiment was carried out in 3 phases: in I and III phase, the concentration of N-NH4 was about 70 mg/L, while in II phase, it was about 430 mg/L. On the MP surface, biofilm-forming microorganisms from the genera Rhodococcus, Pseudomonas and Xantomonas were identified at the lower ammonium concentration. At this concentration, MP-degraders belonging to genera Acidovorax, Gordonia, Pseudomonas, Sphingomonas, and Sphingopyxis were identified in the biofilm. At the higher N-NH4 concentration, the biomass was enriched with bacteria from genera Nitrosospira, Nitrosomonas and Terrimonas, and the number of microorganisms with the potential to degrade MP decreased. Analysis of the MP surface during the experiment has showed the loss of carbonyl groups and formation of carboxyl and hydroxyl groups, which indicated the degradation of MP. Independent of the ammonium concentration in the environment, MP was a carrier of pathogenic microorganisms from the genera Mycobacterium, Enterobacter and Brevundimonas.

Optimised preparation and characterisation of lotus root starch oxidised with sodium hypochlorite (NaOCl) using response surface methodology

In this paper, response surface methodology (RSM) was used to study the optimised process conditions of lotus root starches modified by treatment with sodium hypochlorite (NaOCl). Based on the Box-Behnken design, quadratic models were developed to correlate the reaction variables. Analysis of variance (ANOVA) revealed that the active chlorine content was the most significant variable for the response. Under the experimental conditions in this paper, the calculated carboxyl content (CN<sub>COOH</sub>) of obtained samples was approximately 0.98% ± 0.02% (n = 5). The spectra of Fourier transform infrared (FTIR) spectroscopy displayed that the formation of carboxyl groups successfully occurred on the oxidised lotus root starches. Scanning electron microscope (SEM) analysis showed that the oxidised lotus root starch (CN<sub>COOH</sub>, 0.98%) granules were mostly spherical in shape and their surfaces were slightly rougher than those of native lotus root starch. This work may contribute to providing technical support and theoretical guidance for the production of oxidised lotus root starches using NaOCl as an oxidising agent.

Development of bioanode for versatile applications: microfuel cell system in the presence of alcohol and glucose

The purpose of this work is to develop a bioanode using the enzymes of glucose oxidase (GOx) and alcohol dehydrogenase (ADH) as catalysts to oxidised glucose and alcohol present in different beverages. The study was carried out using the covalent bonding method for both enzymes via the functionalization of carbon nanofibers for the formation of carboxyl groups that can form bonds with the amine groups of the enzyme, as well as using tetrabutylammonium bromide (TBAB) with Nafion. The optimum operation parameters of both enzymes (pH and temperature) were determined for the later evaluation in a microfluidic fuel cell. In addition, using the scanning electrochemical microscopy technique, a local study of enzymatic processes is used to demonstrate that the enzymes immobilized on the same electrode remain active. The evaluation of the microfluidic fuel cell was carried out using different solutions, 0.01 M glucose, 0.01 M ethanol and a mixture of 0.01 M glucose and 0.01 M ethanol, all in phosphate buffer solutions at pH 7, where it was possible to obtain a maximum performance of 5.07 ± 0.1 mW cm−2, and there was a significant increase in current density compared to non-composite solutions (glucose or ethanol). In addition, different alcoholic beverages were used to evaluate the versatility and adaptability of the bi-enzymatic anode electrode with the perspective use in Lab-on-a-Chip systems.

Effect of preoxidation treatment with H2O2 on ruthenium ion-catalyzed oxidation of Yima long flame coal

Environmental concerns have led researches to investigate carbon neutral and sustainable strategies to satisfy well-being of present and future generations, in which coal oxidation becomes a promising approach to achieve this goal. In this study, Yima long flame coal (YLFC) was subjected to ruthenium-ion-catalyzed oxidation (RICO) after peroxidation with H2O2 (PO). The results indicate that the organic matter in YLFC is mainly oxidized into benzenecarboxylic acids, accounting for 70.36% of all the oxidation products, and the yields of the valuable resulting carboxylic acids are significantly elevated by PO from 12.99 wt% to 35.06 wt%, leading to a higher utilization of carbon and lower CO2 emission. Moreover, PO can enhance remarkably the reactivity of the macromolecular precursors of coals, especially highly condensed aromatic species to produce benzenepentacarboxylic acid and mellitic acid more efficiently with a 20-fold increase and 200-fold increase, which is ascribed to the formation of carboxyl groups from other oxygen-containing groups or bonds in coals via PO. The reactive intermediates OH and OOH generated from H2O2 decomposition can attack the carbon atom of alkyl side chains, ether bonds, C=O bonds, and the bridged linkages to undergo a preliminary degradation of macromolecular networks in coals and produce more active sites for the subsequent RICO, leading to the yield and species number increase of carboxylic acids via PO.

Versatile and Facile One-Pot Biosynthesis for Amides and Carboxylic Acids in E. coli by Engineering Auxin Pathways of Plant Microbiomes

The development of enzymatic routes toward amide and carboxylic acid bond formation in bioactive molecular scaffolds using aqueous conditions is a major challenge for biopharmaceutical and fine chemical industrial sectors. We report biocatalytic and kinetic characterization of two indole-3-acetamide (IAM) pathway enzymes, tryptophan-2-monooxygenase (iaaM) and indole-3-acetamide hydrolase (iaaH), present in plant microbiomes that produce indole-3-acetic acid (IAA). In this pathway, tryptophan is converted to indole-3-acetamide by the monooxygenase activity of iaaM, followed by its hydrolysis to form carboxylic acid by iaaH enzyme. Since IAA or auxin is an essential natural plant hormone and an important synthon for fine chemicals, the developed monooxygenase-based bioconversion route has a wider scope compared to currently available synthetic and biocatalytic methods to produce synthetic auxins and a range of amides and carboxylic acids for agrochemical and pharmaceutical applications. To display this, one-pot multienzyme biosynthetic cascades for preparative-scale production of IAA derivatives were performed by incorporating tryptophan synthase and tryptophan halogenase enzymes. We also report the creation of an efficient de novo biosynthesis for IAA and its derivatives from glucose or indoles via a reconstructed IAM pathway in Escherichia coli.

Removal of low-concentration nickel in electroplating wastewater via incomplete decomplexation by ozonation and subsequent resin adsorption

Effective removal of low-concentration chelated nickel in electroplating wastewater to meet the strictest discharge standard for nickel less than 0.1 mg/L has long been a challenging task. Herein, a method combining ozonation and resin adsorption was successfully used to remove the initial total Ni concentration of below 10 mg/L at ozone dosage of 8–38 mg/L. It is notable that the nickel complexation was destroyed by ozone while the co-existing organic matters were not completely mineralized. After ozonation, even the common cation-exchange resin can successfully remove the nickel. The fixed-bed adsorption experiment showed that the working capacity of cation-exchange resin for the ozonated wastewater was 1150 bed volume (BV) at the nickel breakthrough point of 0.1 mg/L, much higher than 5 BV without ozonation treatment. Three-dimensional fluorescence and HPLC-QTOF-MS were employed to characterize the change of Ni-complexes during the treatment process. The decomplexation mechanism of Ni-complexes by ozonation and removal mechanism by cation-exchange resins were proposed. After ozonation, the organic macromolecules were degraded into small molecular acids, which could chelate nickel with one carboxyl group and form positively charged complexes. These nickel complexes were readily adsorbed to the cation-exchange resin via cation exchange or complete complexation, enhancing the removal efficiency. Accordingly, ozone oxidation and subsequent resin adsorption are effective for the removal of low-concentration chelated nickel from electroplating wastewater.

Bioengineering of fibroblast-conditioned polycaprolactone/gelatin electrospun scaffold for skin tissue engineering.

Synthetic tissue engineering scaffolds has poor biocompatiblity with very low angiogenic properties. Conditioning the scaffolds with functional groups, coating with biological components, especially extracellular matrix (ECM), is an excellent strategy for improving their biomechanical and biological properties. In the current study, a composite of polycaprolactone and gelatin (PCL/Gel) was electrospun in the ratio of 70/30 and surface modified with 1% gelatin-coating (G-PCL/Gel) or plasma treatment (P-PCL/Gel). The surface modification was determined by SEM and ATR-FTIR spectroscopy, respectively. The scaffolds were cultured with fibroblast 3T3, then decellularized during freeze-thawing process to fabricate a fibroblast ECM-conditioned PCL/Gel scaffold (FC-PCL/Gel). The swelling and degaradtion as well as in vitro and in vivo biocompatibility and angiogenic properties of the scaffolds were evaluated. The structure of the surface-modified G-PCL/Gel and P-PCL/Gel were unique and not changed compared with the PCL/Gel scaffolds. ATR-FTIR analysis admitted the formation of oxygen-containing groups, hydroxyl and carboxyl, on the surface of the P-PCL/Gel scaffold. The SEM micrographs and DAPI staining confirmed the cell attachment and the ECM deposition on the platform and successful removal of the cells after decellularization. P-PCL/Gel showed better cell attachment, ECM secretion and deposition after decellularization compared with G-PCL/Gel. The FC-PCL/Gel was considered as an optimized scaffold for further assays in this study. The FC-PCL/Gel showed increased hydrophilic behavior and cytobiocompatibility compared with P-PCL/Gel. The ECM on the FC-PCL/Gel scaffold showed a gradual degradation during 30days of degradation time, as a small amount of ECM remained over the FC-PCL/Gel scaffold at day 30. The FC-PCL/Gel showed significant biocompatibility and improved angiogenic property compared with P-PCL/Gel when subcutaneously implanted in a mouse animal model for 7 and 28days. Our findings suggest FC-PCL/Gel as an excellent biomimetic construct with high angiogenic properties. This bioengineered construct can serve as a possible application in our future pre-clinical and clinical studies for skin regeneration.