Search

Phagocytosis performed by a macrophage involves complex membrane trafficking and reorganization among various membranous cellular structures including phagosomes and vesicles derived from the phagosomes known as phagosome-derived vesicles. The present work reports on development of a technique that allows to specifically label the phagosome-derived vesicles in macrophages with a membrane dye. The technique is based on the use of microfabricated microparticles that are made of a thermosensitive nonbiodegradable polymer poly(N-isopropylacrylamide) (PNIPAM) or its derivative and contain a membrane dye 1,1′-dialkyl-3,3,3′,3′-tetramethylindodicarbocyanine (DiI). The microparticles can be phagocytosed by RAW264.7 macrophages into their phagosomes, resulting in formation of intracellular DiI-positive vesicles derived from the phagosomes. The DiI-positive vesicles are motile and acidic; can be stained by fluorescently labelled dextran added in the culture medium; and can accumulate around new phagosomes, indicating that they possess properties of lysosomes. This technique is also applicable to another membrane dye 3,3'-dioctadecyloxacarbocyanine (DiO) and holds great potential to be useful for advancing our understanding of phagocytosis. STATEMENT OF SIGNIFICANCE: Phagocytosis performed by macrophages is a cellular process of great importance to various applications of biomaterials such as drug delivery and medical implantation. This work reports on a technique for characterizing phagocytosis based on the use of poly(N-isopropylacrylamide), which is a major biomaterial with numerous applications. This technique is the first of its kind and has generated an original finding about phagocytosis. In addition to drug delivery and medical implantation, phagocytosis plays critical roles in diseases, injuries and vaccination. This work could thus attract immediate and widespread interests in the field of biomaterials science and engineering.

The stem and root bark of Ulmus macrocarpa Hance has been used as traditional pharmacological agent against inflammation related disorders. The objective of this study was to explore the impact of Ulmus macrocarpa Hance extract (UME) on human gut microbiota. A randomized placebo-controlled clinical study was conducted in healthy adults. The study subjects were given 500 mg/day of UME or placebo orally for 4 weeks. Eighty fecal samples were collected at baseline and 4 weeks of UME or placebo intervention. The gut microbiota variation was evaluated by 16S rRNA profiling. The microbial response was highly personalized, and no statistically significant differences was observed in both species richness and abundance. The number of bacterial species identified in study subjects ranged from 86 to 182 species. The analysis for taxonomical changes revealed an increase in Eubacterium ventriosum, Blautia faecis, Ruminococcus gnavus in the UME group. Functional enrichment of bacterial genes showed an increase in primary and secondary bile acid biosynthesis in UME group. Having known from previous studies Eubacterium regulated bile acid homeostasis in protecting gut microbial architecture and immunity, we suggest that UME supplementation might enhance host immunity by modulating gut microbiota. This is the first stage study and forthcoming clinical studies with larger participants are needed to confirm these findings.

Physiological response and transcriptome changes were observed to investigate the effects on the growth, metabolism and genetic changes of

Evolutionary immune system upgradation is done by all living organism to survive from the invading pathogens. Insects has a strong defense system comprising of anatomical barrier, humoral antimicrobial peptide (AMP) production and cellular immune components. Locusta migratoria (L. migratoria) is an agricultural pest insect migrating long distance might encounter distinct pathogens. Owing to this, we aimed in identifying AMPs present in the L. migratoria and elucidate the antimicrobial activity. The migratory locust was immunized with Escherichia coli, Staphylococcus aureus, Candida albicans mixture, then RNA was isolated and sequenced. The L. migratoria transcriptome was de novo assembled using trinity and screened for AMPs propensity specifically molecular and aggregation properties. The novelty is tested by blasting in known AMP databases. Finally, obtained novel putative AMPs were then tested for antimicrobial and hemolytic activity. The prediction resulted in 3,524 putative AMPs which was further screened down to ten AMPs for final testing. Two peptides showing promising antimicrobial effects were obtained. All the analyzed peptides showed no hemolysis confirms its non-toxicity. Thus, our peptides could be promising drug candidate and can be used as an alternative to antibacterial or antifungal therapy with further validations.

Zophobas atratus which is also referred as giant meal worm, belongs to the largest darkling beetle family. The rich protein and fat content in the giant meal worm made it as excellent protein source in pet feed and thus instigated the commercial rearing. Insect antimicrobial peptides (AMPs) have therapeutic potential with wide range of activity against bacteria, fungus, parasites, and viruses. However, there is a lack of study of AMPs from Zophobas atratus. We have immunized the giant meal worm with Escherichia coli, Staphylococcus aureus, Candida albicans and total RNA was isolated and sequenced. De novo transcriptome assembly and functional annotations was done. The AMPs were predicted using in silico pipeline from transcriptome data. A total of 355,771,565 raw reads with 26.6 gigabytes was obtained. After trimming and low-quality sequences removal, 328,196,384 (92.2%) total clean reads was obtained. A total of 47,635 unigenes were assembled with the average length of 1109 bp. AMP pipeline predicted a total of 752 peptides of which 177 were novel AMPs all of which are non-allergens. Based on the α-helix secondary structure requirement for higher efficiency 14 peptides were synthesized and tested in vitro to determine the minimum inhibitory concentrations. Eventually, the peptides Za 7, Za 15, Za 22 were selected as the prime candidates for the development of antimicrobial agents and none of them showed hemolytic activity up to 100 μg/mL. Our data provides an insight in Zophobas atratus transcriptome derived AMPs and understanding its antimicrobial activity.

Global climate change is heavily affected by an increase in CO2. As one of several efforts to cope with this, research on poplar, a representative, fast growing, and model organism in plants, is actively underway. The effects of elevated atmospheric CO2 on the metabolism, growth, and transcriptome of poplar were investigated to predict productivity in an environment where CO2 concentrations are increasing. Poplar trees were grown at ambient (400 ppm) or elevated CO2 concentrations (1.4× ambient, 560 ppm, and 1.8× ambient, 720 ppm) for 16 weeks in open-top chambers (OTCs). We analyzed the differences in the transcriptomes of Populusalba × Populus glandulosa clone “Clivus” and Populus euramericana clone “I-476” using high-throughput sequencing techniques and elucidated the functions of the differentially expressed genes (DEGs) using various functional annotation methods. About 272,355 contigs and 207,063 unigenes were obtained from transcriptome assembly with the Trinity assembly package. Common DEGs were identified which were consistently regulated in both the elevated CO2 concentrations. In Clivus 29, common DEGs were found, and most of these correspond to cell wall proteins, especially hydroxyproline-rich glycoproteins (HRGP), or related to fatty acid metabolism. Concomitantly, in I-476, 25 were identified, and they were related to heat shock protein (HSP) chaperone family, photosynthesis, nitrogen metabolism, and carbon metabolism. In addition, carbohydrate contents, including starch and total soluble sugar, were significantly increased in response to elevated CO2. These data should be useful for future gene discovery, molecular studies, and tree improvement strategies for the upcoming increased-CO2 environments.

The traditional electrically conductive adhesives (ECAs) include heterogeneous metallic and/or carbon-based fillers blended with the organic adhesive polymer matrix. However, those heterogeneous-bl...

In plants, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a main enzyme in the glycolytic pathway. It plays an essential role in glycerolipid metabolism and response to various stresses. To examine the function of PsGAPDH (Pleurotus sajor-caju GAPDH) in response to abiotic stress, we generated transgenic rice plants with single-copy/intergenic/homozygous overexpression PsGAPDH (PsGAPDH-OX) and investigated their responses to salinity stress. Seedling growth and germination rates of PsGAPDH-OX were significantly increased under salt stress conditions compared to those of the wild type. To elucidate the role of PsGAPDH-OX in salt stress tolerance of rice, an Illumina HiSeq 2000 platform was used to analyze transcriptome profiles of leaves under salt stress. Analysis results of sequencing data showed that 1124 transcripts were differentially expressed. Using the list of differentially expressed genes (DEGs), functional enrichment analyses of DEGs such as Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were performed. KEGG pathway enrichment analysis revealed that unigenes exhibiting differential expression were involved in starch and sucrose metabolism. Interestingly, trehalose-6-phosphate synthase (TPS) genes, of which expression was enhanced by abiotic stress, showed a significant difference in PsGAPDH-OX. Findings of this study suggest that PsGAPDH plays a role in the adaptation of rice plants to salt stress.

Antimicrobial peptides (AMPs) are the frontline innate defense system evolutionarily preserved in insects to combat invading pathogens. These AMPs could serve as an alternative to classical antibiotics to overcome the burden of treating multidrug resistant bacteria. Psacotheasin, a knottin type AMP was isolated from Psacothea hilaris and shown to exhibit antimicrobial activity, especially against fungi through apoptosis mediated cell death. In this study, we aimed to identify novel probable AMPs from Psacothea hilaris, the yellow spotted longicorn beetle. The beetle was immunized with the two bacterial strains (E. coli and S. aureus), and the yeast strain C. albicans. After immunization, total RNA was isolated and sequenced in Illumina platform. Then, beetle transcriptome was de novo assembled and searched for putative AMPs with the known physiochemical features of the AMPs. A selection of AMP candidates were synthesized and tested for antimicrobial activity. Four peptides showed stronger activity against E. coli than the control AMP, melittin while one peptide showed similar activity against S. aureus. Moreover, four peptides and two peptides showed antifungal activity stronger than and similar to melittin, respectively. Collectively one peptide showed both antibacterial and antifungal activity superior to melittin, thus, it provides a potent antimicrobial peptide. All the peptides showed no hemolysis in all the tested concentrations. These results suggest that in silico mining of insects&rsquo, transcriptome could be a promising tool to obtain and optimize novel AMPs for human needs.

Lignin is an aromatic-rich biomass polymer that is cheap, abundant, and sustainable. However, its application in the solid electrolyte field is rare due to challenges in well-defined polymer synthesis. Herein, the synthesis of lignin-graft-poly(ethylene glycol) (PEG) and its conductivity test for a solid electrolyte application are demonstrated. The main steps of synthesis include functionalization of natural lignin's hydroxyl to alkene, followed by graft-copolymerization of PEG thiol to the lignin via photoredox thiol-ene reaction. Two lignin-graft-PEGs are prepared having 22 wt% lignin (lignin-graft-PEG 550) and 34 wt% lignin (lignin-graft-PEG 2000). Then, new polymer electrolytes for conductivity tests are prepared via addition of lithium bis-trifluoromethanesulfonimide. The polymer graft electrolytes exhibit ionic conductivity up to 1.4 × 10-4 S cm-1 at 35 °C. The presence of lignin moderately impacts conductivity at elevated temperature compared to homopolymer PEG. Furthermore, the ionic conductivity of lignin-graft-PEG at ambient temperature is significantly higher than homopolymer PEG precedents.

A glucose-based bioadhesive, poly(2-methacrylamido glucopyranose-co-N-methacryloyl-3,4-dihydroxyl-L-phenylalanine-co-8-azidooctyl methacrylate) [poly(MG-co-MDOPA-co-AOM)], has been synthesized by thermally-initiated free radical polymerization. The new bioadhesive is composed of three modules: a hydrophilic glycopolymer segment, a mussel-inspired catechol segment, and a crosslinking azide segment. Poly(ethylene glycol) (PEG)-based crosslinker, (1R,8S,9s)-bicyclo[6.1.0]non-4-yn-9-ylmethyl PEG (BCN-PEG) was synthesized separately. Bulk adhesion properties of the terpolymer were enhanced by covalent bond forming crosslinking via strain-promoted azide–alkyne cycloaddition (SPAAC). The occurrence of SPAAC was confirmed by 1H NMR and FT-IR. After moistening the adhesive and the crosslinker, BCN-PEG with water, adhesion properties were examined by a lap shear strength test on porcine skins. The control of adhesion was studied under various crosslinker concentrations, crosslinking durations, and crosslinker lengths. Even without crosslinking, the new terpolymer adhesive demonstrated 20-fold higher adhesion strength (115 kPa) compared to a commercial rubber cement (5.8 kPa). The most significant factor to control for adhesion was crosslinker length. BCN-PEG was prepared with 134 and 43 repeating units of PEG. Crosslinking with the long crosslinker, BCN-PEG (PEG repeating units: 134), did not enhance adhesion strength meaningfully. However, crosslinking the short crosslinker BCN-PEG (repeating units: 43) showed significant improvement in work of adhesion (150% higher than uncrosslinked). The overall revealed features of strong adhesion on biological surfaces, structural similarity to natural carbohydrate, water compatibility, controllability of adhesion strength, and non-toxic adhesion enhancement principle via SPAAC crosslinking, suggest that the new glucose-based bioadhesive can be successfully used for biomedical applications.

Fleshy fruits are the most demanded fruits because of their organoleptic qualities and nutritional values. The genus Prunus is a rich source of diversified stone/drupe fruits such as almonds, apricots, plums, sweet cherries, peaches, and nectarines. The fruit-ripening process in Prunus involves coordinated biochemical and physiological changes resulting in changes in fruit texture, aroma gain, color change in the pericarp, sugar/organic acid balance, fruit growth, and weight gain. There are different varieties of peaches with unique palatable qualities and gaining knowledge in the genetics behind these quality traits helps in seedling selection for breeding programs. In addition, peaches have shorter post-harvest life due to excessive softening, resulting in fruit quality reduction and market loss. Many studies have been executed to understand the softening process at the molecular level to find the genetic basis. To summarize, this review focused on the molecular aspects of peach fruit quality attributes and their related genetics to understand the underlying mechanisms.

Classical antibiotics are the foremost treatment strategy against microbial infections. Overuse of this has led to the evolution of antimicrobial resistance. Antimicrobial peptides (AMPs) are natural defense elements present across many species including humans, insects, bacteria, and plants. Insect AMPs are our area of interest, because of their stronger abilities in host defense. We have deciphered AMPs from an endangered species Parnassius bremeri, commonly known as the red spotted apollo butterfly. It belongs to the second largest insect order Lepidoptera, comprised of butterflies and moths, and lives in the high altitudes of Russia, China, and Korea. We aimed at identifying the AMPs from the larvae stages. The rationale of choosing this stage is that the P. bremeri larvae development occurs at extremely low temperature conditions, which might serve as external stimuli for AMP production. RNA was isolated from larvae (L1 to L5) instar stages and subjected to next generation sequencing. The transcriptomes obtained were curated in in-silico pipelines. The peptides obtained were screened for requisite AMP physicochemical properties and in vitro antimicrobial activity. With the sequential screening and validation, we obtained fifteen candidate AMPs. One peptide TPS–032 showed promising antimicrobial activity against Porphyromonas gingivalis, a primary causative organism of periodontitis.

The current use of lignin as a raw material is very limited and focused only on cheap and poorly defined nonfunctional materials mainly due to challenges in synthetic modification of lignin. Herein, we report a new low energy and environmentally friendly lignin modification method induced by visible blue light. The key modification reaction is a photoredox catalyzed thiol–ene reaction. The lignin was modified to possess alkenes for the thiol–ene reaction. Three photochemical reagents—Ru(bpy)3Cl2, Eosin Y, and 2,2-dimethoxy-2-phenylacetophenone—were tested to determine the best thiol–ene modification method. The thiol–ene reaction between lignin–alkene and 1-decanethiol revealed that Ru(bpy)3Cl2 was the most efficient, resulting in conversions of 97% with 2.5 mol % catalyst loading. The Ru(bpy)3Cl2 was further investigated with diverse thiol compounds. All tested thiol–ene reactions showed excellent efficiencies, with conversions of 93–97% under low-energy 3W blue LED light. In particular, thiol terminal p...

Lignin is an important source of synthetic materials because of its abundance in nature, low cost, stable supply, and no competition to the human food supply. Lignin, a cross-linked phenolic polymer, contains a large number of aromatic groups that can be used as a substitute for petroleum-based aromatic fine chemicals. However, modification of lignin is necessary for its application in advanced materials due to its chemically inert nature and structural complexity. Polymeric modification of lignin via graft copolymerization represents an important avenue for modification because this method forms stable covalent bond linkages between lignin and synthetic functional polymers. In this review, we discuss recent synthetic strategies toward polymeric modification of lignin using graft copolymerization and the special properties and applications of the produced lignin copolymers. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 3515–3528

A general method, focusing upon olefin metathesis, was developed for the recovery of homogeneous olefin metathesis catalysts from crude reaction solutions. This method utilizes the supramolecular host–guest interaction between an azobenzene-modified N-heterocyclic carbene ligand and a silica-grafted β-cyclodextrin to remove homogeneous catalyst in a heterogeneous manner, allowing for the recovery of more than 97% of ruthenium in solution. The robust and simple nature of the guest molecule allows for the application of this method to a wide range of homogeneous catalysts. This study reports the synthesis and characterization of the said precatalyst and host compound as well as proof-of-concept recovery trials for a number of common substrates, with the residual ruthenium content of reaction mixtures evaluated by inductively coupled plasma mass spectrometry.

A bioinspired, modular terpolymer adhesive, poly(N-methacryloyl-3,4-dihydroxyl-l-phenylalanine-co-9-(acryloyloxy)butyl anthracene-9-carboxylate-co-acrylic acid), has been synthesized containing three different functionalities: a photo-cross-linking segment, a wet interfacial adhesion segment, and a water-soluble segment. The synthesized adhesive polymer is the first example of a single-phase, photo-cross-linkable adhesive which does not require additional photoinitiator or other cross-linking agents. The terpolymer demonstrates strong adhesion when it swells in water and/or ethanol. The terpolymer is composed of three repeating units: N-methacryloyl-3,4-dihydroxyl-l-phenylalanine (MDOPA), which has been known to generate strong adhesion under wet conditions, poly(acrylic acid), which has been known to increase water solubility of polymers, and a photo-cross-linking segment consisting of an anthracene-based monomer used for enhancement of cohesion properties via UV irradiation (352 nm). A photomediated [4 + 4] cycloaddition reaction of anthracene results in the cross-linking of individual polymer chains after interfacial adhesion between substrates and adhesive polymers. Chemically, the covalent photo-cross-linking was confirmed by UV-vis

We report the synthesis of a highly-functional macromonomer, and subsequent crosslinkable poly(ethylene glycol) (PEG)-based bottlebrush polymers prepared via graft-through ring-opening metathesis polymerization (ROMP). This work makes two important additions to the repertoire of bottlebrush polymers: (1) the first example of a catechol-derived brush adhesive relying on an internal ketone for post-polymerization modification; and (2) the post-polymerization modification is utilized to greatly affect the mechanical properties of the bulk material through oxime functionalization and subsequent metal-free click chemistry beginning from the innocuous, and easily introduced, internal ketone. This form of oxime ligation was demonstrated with a series of oxyamines, with degrees of functionalization on the range of 18–100%, while introducing further functionality in the form of azide groups, which were rapidly converted to corresponding triazoles via metal-free click chemistry using the crosslinker (1R, 8S, 9S)-bicyclo[6.1.0]non-4-yn-9-ylmethyl (BCN) bisfunctionalized PEG (Mn = ∼6000 g mol−1). Under these conditions, the transformation from soluble polymer solution to soft hydrogel occurs within minutes. The polymer described herein stands testament to the ability of modularly-designed macromonomers to dictate the structure and properties of downstream materials in a predicable fashion.

A photo-responsive bio-inspired adhesive consisting of a zwitterionic polymer, poly(sulfobetaine methacrylate) (pSBMA), DOPA (3,4-dihydroxyphenylalanine), and a photocleavable nitrobenzyloxycarbonyl containing crosslinker was synthesized by thermally-initiated free radical polymerization. The main component, pSBMA, is a highly hydrophilic zwitterionic polymer with a high potential for biomedical application. The DOPA functionality, an extensively studied major component of the adhesion properties in mussels, is known to universally enhance polymeric adhesion properties even in the presence of water. The third component, a nitrobenzyl-containing dimethacrylate crosslinker, is efficiently cleaved upon UV irradiation. Proton NMR analysis of the crosslinker, 2-nitro-1,3-benzenedimethanol dimethacrylate (NBDM), demonstrates that photocleavage of the o-nitrobenzyl ester occurs rapidly for 30 minutes, then gradually continues for another 3 hours. The same patterns of photocleavage were observed in a terpolymer adhesive containing the nitrobenzyl crosslinker, poly(N-methacryloyl-3,4-dihydroxyl-L-phenylalanine-co-sulfobetaine methacrylate-co-2-nitro-1,3-benzenedimethanol dimethacrylate), poly(MDOPA-co-SBMA-co-NBDM). The terpolymer adhesive demonstrated a reduction in adhesion properties over the course of irradiation corresponding to the cleavage rate observed by 1H NMR analysis of NBDM. After 30 minutes of UV irradiation the original adhesion strength, 341 kPa, was decreased to 223 kPa, corresponding to a 35% reduction. The adhesion strength continued to decrease to 150 kPa at the 3 hours mark, a 56% reduction compared to the original adhesion strength.

Glycopolymers are an important class of biomaterials which include carbohydrate moieties in their polymer structure. In addition to biological research on the interactions of glycopolymers with lectin-carbonate, glycopolymers have recently been used as a new synthetic biomaterial for direct therapeutic methods, medical adhesives, and biosensors. Thus, a comprehensive understanding of new advances in glycopolymer research is essential for the next level of biomaterial studies. This review article highlights commonly used glycopolymer synthesis methods and biomedical applications thereof. Glycopolymers can be synthesized by modern polymerization methods that can control the molecular weight, molecular weight distribution, chemical functionality, and polymer architecture. The polymerizations include free radical polymerization, atom transfer radical polymerization, reversible addition-fragmentation chain-transfer polymerization, and nitroxide-mediated polymerization. Because the carbohydrate-lectin interactions with glycopolymers are involved in many biological processes, carbohydrates containing glycopolymers are used in (1) fundamental studies to understand the specificity and strength of biological binding, (2) controllable interactions to prevent microorganism adhesion to human cells, (3) large scale bulk adhesives for medical applications, (4) biocompatible therapeutic nanoparticles, (5) direct drug delivery vehicles, and (6) precise quantitative measurement of biosensor materials that can detect physiological signals.

An insect’s innate immune system is the front line of defense against many invading microorganisms. One of the important components of this defense system is antimicrobial peptides (AMPs). Papiliocin is a well-studied antimicrobial peptide (AMP) isolated from the swallowtail butterfly, Papilio xuthus, and it was previously reported to be effective against Gram-positive bacteria, Gram-negative bacteria, and fungi, particularly in drug resistant Gram-negative bacteria. Hence, we aimed to identify novel AMPs from Papilio xuthus using its transcriptome. We immunized the swallowtail butterfly with Escherichia coli, Staphylococcus aureus, Candida albicans, and the total RNA was isolated. De novo transcriptome assembly and functional annotations were conducted, and AMPs were predicted using an in-silico pipeline. The obtained 344,804,442 raw reads were then pre-processed to retrieve 312,509,806 (90.6%) total clean reads. A total of 38,272 unigenes were assembled with the average length of 1010 bp. Differential gene expression analysis identified 584 and 1409 upregulated and downregulated genes, respectively. The physicochemical, aggregation, and allergen propensity were used as filtration criteria. A total of 248 peptides were predicted using our in-house pipeline and the known AMPs were removed, resulting in 193 novel peptides. Finally, seven peptides were tested in vitro and three peptides (Px 5, 6, and 7) showed stronger antimicrobial activity against Gram-negative bacteria and yeast. All the tested peptides were non-allergens. The identified novel AMPs may serve as potential candidates for future antimicrobial studies.

Lignin can be an important source of synthetic commodity materials owing to its abundance in nature and low production cost. The current use of lignin as a raw material, however, is very limited and focused only on cheap and poorly defined nonfunctional materials. Herein we report a new lignin-containing functional polymer, lignin-graft-poly(5-acetylaminopentyl acrylate) (lignin-graft-PAA), which has been prepared by the covalent linkage of chemically modified lignin with PAA, which is an end-group functionalized polymer. This work makes two significant advances in the study of lignin-containing polymers: (1) lignin-graft-PAA is the first example of lignin being modified by a polymer with sophisticated structure, and (2) lignin-graft-PAA shows a special performance, autonomic self-healing properties, which have not yet been seen in lignin-containing polymers. The key synthetic step in this process utilizes a copper-catalyzed azide–alkyne cycloaddition or “click” reaction in order to join together the lign...

A highly efficient transition metal catalyst removal method is developed. The water-soluble catalyst contains a newly-designed NHC ligand for the catalyst removal via host-guest interactions. The new NHC ligand possesses an adamantyl (guest) tethered linear ethylene glycol units for hydrophobic inclusion into the cavity of a β-cyclodextrin (β-CD) host compound. The new NHC ligand was applied to a Ru-based olefin metathesis catalyst. The Ru catalyst demonstrated excellent activity in representative ring-closing metathesis (RCM) and ring-opening metathesis polymerization (ROMP) reactions in aqueous media as well as organic solvent, CH(2)Cl(2). After the reaction was complete, the lingering Ru residue was removed from the aqueous solution with the efficiency of more than 99% (53 ppm of Ru residue) by simple filtration utilizing a host-guest interaction between insoluble silica-grafted β-CD (host) and the adamantyl moiety (guest) on the catalyst. The new Ru catalyst also demonstrated high removal efficiency via extraction when the reaction is run in organic solvent by partitioning the crude reaction mixture between layers of diethyl ether and water. In this way, the catalyst stays in aqueous layer only. In organic layer, the residual Ru amount was only 0.14 ppm in the RCM reactions of diallyl compounds.

A study of reaction kinetics and removal efficiency of a family of ruthenium (Ru)-based olefin metathesis catalysts containing ethylene-glycol-oligomer-tethered N-heterocyclic carbene (NHC) ligands has been carried out, with a focus on variation of ethylene glycol oligomer length. The length of ethylene glycol oligomer was precisely defined by sequential addition of repeating units. Due to the dual solubility of ethylene glycol oligomer, the produced catalyst was highly soluble in both aqueous and organic solvents (dichloromethane). In aqueous solution, the polarity increase with longer ethylene glycol oligomers enhanced the reactivity in homogeneous solution. The length of ethylene glycol oligomer did not significantly affect olefin metathesis rate in organic solution. Yet the removal efficiency of catalyst strongly relies on the length of ethylene glycol oligomer. A longer ethylene glycol oligomer demonstrated better catalyst removal efficiency. The tested catalyst removal method was aqueous extraction from organic solution using its higher water solubility property compared to its lower organic solvent (dichloromethane) solubility property. The results obtained from the aqueous extraction catalyst removal method demonstrated similar and/or better removal rates compared to previously reported host-guest catalyst removal methods.

A highly removable N-heterocyclic carbene ligand for a transition-metal catalyst in aqueous media via host–guest interactions has been developed. Water-soluble adamantyl tethered ethylene glycol in the ligand leads a hydrophobic inclusion into the cavity of β-cyclodextrin. Ruthenium (Ru) olefin metathesis catalyst with this ligand demonstrated excellent performance in various metathesis reactions in water as well as in CH2Cl2, and removal of residual Ru was performed via filtration utilizing a host–guest interaction and extraction.

Nanocomposites based on synthetic polymers grafted from kraft lignin with average particle size of 5 nm were synthesized using atom transfer radical polymerization (ATRP). Lignin macroinitiators were prepared, and polystyrene and poly(methyl methacrylate) were polymerized with target degree of polymerization of 450 resulting in materials having lignin mass fractions of 4.5%, 8.3%, and 22.1% for the poly(methyl methacrylate) samples and 3.2%, 7.1%, and 19.6% for the polystyrene samples. Tensile testing showed a decreased modulus but enhanced toughness of all nanocomposites compared to homopolymers, and the poly(methyl methacrylate)-grafted samples had nearly twice the ultimate elongation as the polystyrene grafts at high graft density. Both types of grafted nanocomposites had toughness values that were greater than 10-times that of the corresponding kraft-lignin/polymer blend system, indicating the potential of ATRP as the basis for the ‘one component’ composite approach towards more sustainable polymeric materials. Dynamical mechanical analysis was used to measure softening temperatures, and both the polystyrene-grafted and poly(methyl methacrylate)-grafted nanocomposites had a peak in the loss modulus that was higher than the corresponding homopolymer, consistent with strong polymer–lignin interactions. Lignin grafted with thermoplastic polymers could be an important material based on an inexpensive, renewable feedstock that offers unique mechanical properties compared with many other nanocomposites based on inorganic nanoparticles. Our results indicate that ATRP is well suited for preparing lignin-based thermoplastics and could be the basis for hybrid materials that make effective use of this important renewable resource.

In this study, electroless-plating of a nickel-phosphor (Ni&ndash, P) thin film on surface-controlled thermoelectric elements was developed to significantly increase the bonding strength between Bi&ndash, Te materials and copper (Cu) electrodes in thermoelectric modules. Without electroless Ni&ndash, P plating, the effect of surface roughness on the bonding strength was negligible. Brittle SnTe intermetallic compounds were formed at the bonding interface of the thermoelectric elements and defects such as pores were generated at the bonding interface owing to poor wettability with the solder. However, defects were not present at the bonding interface of the specimen subjected to electroless Ni&ndash, P plating, and the electroless Ni&ndash, P plating layer acted as a diffusion barrier toward Sn and Te. The bonding strength was higher when the specimen was subjected to Ni&ndash, P plating compared with that without Ni&ndash, P plating, and it improved with increasing surface roughness. As electroless Ni&ndash, P plating improved the wettability with molten solder, the increase in bonding strength was attributed to the formation of a thicker solder reaction layer below the bonding interface owing to an increase in the bonding interface with the solder at higher surface roughness.