Molecular Size Analysis Research Articles

Ultrasmall Superparamagnetic Iron Oxide Nanoparticles as Nanocarriers for Magnetic Resonance Imaging: Development and In Vivo Characterization.

Ultrasmall superparamagnetic iron oxide nanoparticles (uSPIOs) are attractive platforms for the development of smart contrast agents for magnetic resonance imaging (MRI). Oleic acid-capped uSPIOs are commercially available yet hydrophobic, hindering in vivo applications. A hydrophilic ligand with high affinity toward uSPIO surfaces can render uSPIOs water-soluble, biocompatible, and highly stable under physiological conditions. A small overall hydrodynamic diameter ensures optimal pharmacokinetics, tumor delivery profiles, and, of particular interest, enhanced T 1 MR contrasts. In this study, for the first time, we synthesized a ligand that not only fulfills the as-proposed properties but also provides multiple reactive groups for further modifications. The synthesis delivers a facile approach using commercially available reactants, with resultant uSPIO-ligand constructs assembled through a single-step ligand exchange process. Structural and molecular size analyses confirmed size uniformity and small hydrodynamic diameter of the constructs. On average, 43 reactive amine groups were present per uSPIO nanoparticle. Its r 1 relaxivity has been tested on a 7 Tesla MR instrument and is comparable to that of the clinically available T 1 gadolinium-based contrast agent GBCA (1 vs 3 mM-1 s-1, respectively). A significant decrease in tumor T1 (15%) within 1 h of injection and complete signal recovery after 2 h were detected with a dose of 7 μg Fe/g mouse. The agent also has high r 2 relaxivity and can be used for T 2 contrast-enhanced MRI. Taken together, good relaxation and delivery properties and the presence of multiple surface reactive groups can facilitate its application as a universal MRI-compatible nanocarrier platform.

MO548: Endothelial Cell Derived Exosomes Promote Vascular Smooth Muscle Cell Calcification and Senescence by Regulating the Β-Catenin Signaling Pathway Through miRNA-29B-3p

Abstract BACKGROUND AND AIMS Vascular calcification is an important risk factor for high incidence of cardiovascular events and death in patients with chronic kidney disease (CKD). The mechanism of how the calcification signal in early CKD is transmitted to vascular smooth muscle cells (VSMCs) from endothelial cells in the tunica intima to initiate the whole process of vascular calcification remains to be elucidated. The aim of this study was to investigate the effect of miRNA-29B-3p in exosomes derived from vascular endothelial cells under high phosphorus stimulation on VSMC calcification and senescence. METHOD Firstly, human umbilical vein endothelial cells (HUVECs) were divided into the high-phosphorus group (HP-HUVEC, 3mmol/L) and the control group (NP-HUVEC) for exosomes isolation by superspeed centrifugation. Transmission electron microscopy, molecular size analysis and Western blot analysis of exosome markers were used to identify exosomes. Secondly, VSMCs were treated with HP-HUVEC-Exo, NP-HUVEC-Exo and blank control. Then, HUVECs were transfection with miR-29b-3p mimic, miR-29b-3p inhibitor and their controls for the extraction of exosomes. VSMCs were further treated with Exo-miR-29b-3p mimic, Exo-miR-29b-3p inhibitor and their controls. Western Blot was used to detect the expressions of calcification-related protein Runx2, senescence-related protein P21 and β-catenin pathway-related proteins (GSK-3β and β-catenin). Alizarin red staining, ALP activity detection and calcium (Ca) content determination were used to detect the calcification of VSMC. The senescence of VSMC was detected by SA-β-gal staining and the expression of miR-29b-3p was detected by qRT-PCR. RESULTS The expression of marker proteins CD9 and CD63 was observed by Western Blot, the diameter of particle size analysis was about 172.3 ± 72.5 nm and the structure of typical lipid double-layer membrane was observed, suggesting that exosomes were extracted. Compared with the NP-HUVEC-Exo and blank control group, Western Blot showed that the expression of Runx2, P21 and β-catenin was up-regulated and the expression of GSK-3β was down-regulated in VSMC treated with HP-HUVEC-Exo. VSMC treated with HP-HUVEC-Exo also showed up-regulated miR-29b-3p expression, higher ALP activity and Ca content, suggesting exosomes from high phosphorus-stimulated endothelial cells induced calcification and senescence of VSMCs. Compared with the control group, the expression of Runx2 and P21 was up-regulated and showed more significant calcification and aging characteristics and the expression of GSK-3β was down-regulated and the expression of β-catenin was up-regulated in VSMC treated with Exo-miR-29b-3p mimic. VSMC treated with Exo-miR-29b-3p inhibitor showed the opposite results, indicating that miR-29b-3p could repress GSK-3β and activate β-catenin pathway to promoted VSMC calcification/senescence. CONCLUSION Exosomes produced from high phosphorus stimulates endothelial cells could induce the calcification and senescence of VSMC by conveying miR-29b-3p to VSMC and then regulating the β-catenin signaling pathway.

MO555: Exosomes From Endothelial Cells to Smooth Muscle Cells Induce Vascular Calcification in Early Chronic Kidney Disease

Abstract BACKGROUND AND AIMS Vascular calcification can occur in the early stages of chronic kidney disease (CKD) and result in a poor prognosis. How the calcification signal in the blood is transduced from endothelial cells in the tunica intima to vascular smooth muscle cells in the tunica media in the early stages of CKD is still unknown. The aim of this study was to explore the role of exosomes in signal transduction in vascular calcification. METHOD Exosomes were isolated from normal phosphate- and high phosphate-stimulated human umbilical vein endothelial cells (HUVECs) by superspeed centrifugation. We used transmission electron microscopy, molecular size analysis and Western blot analysis of exosome markers to identify exosomes (Figure 1). VSMC calcification was assessed by Alizarin Red Staining and Western blot. Proteomics analysis and miRNA microarray analysis were carried out to detect the differences in exosomal proteins and miRNAs. The results were analysed via Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. RESULTS Fluorescence microscopy verified that VSMCs took up exosomes from HUVECs. Exosomes isolated from high phosphate-stimulated HUVECs (HP-HUVEC-exos) induced VSMC calcification (assessed by Alizarin Red Staining), increased osteopontin expression and increased alkaline phosphatase activity (Figure 2). Proteomics analysis showed different protein expressions including STAT1, STAT3, HDAC1, PARP1, WDR5 et al. MiRNA microarray analysis showed different miRNA levels including miR-223–3p, miR-6776–5p, miR-6851–5p, miR-2116–3p, miR-6849–5p et al. (Figure 3). Target GO analysis showed that both miRNA and protein difference focused on some biological processes (RNA splicing, mRNA processing, RNA targeting), molecular function (cadherin binding, cell adhesion molecule binding, ubiquitin-like protein ligase binding) and cellular component (focal adhesion, cell-substrate junction, spliceosomal complex). KEGG analysis revealed that both miRNA and protein differences were focused on pathways associated with the cell cycle, virus infection and protein processing in the endoplasmic reticulum. CONCLUSION Exosome-mediated miRNA and protein transfer from endothelial cells to VSMCs may induce vascular calcification via RNA processing, protein processing and cell adhesion.

Corn arabinoxylan has a repeating structure of subunits of high branch complexity with slow gut microbiota fermentation

Corn arabinoxylan (CAX), a cell wall-derived dietary fiber, was extracted with alkali, partially purified, and treated with hydrolytic enzymes in order to investigate the relationship of fine structure and fermentability by the human gut microbiota. Glycosyl composition and linkage analysis of CAX and two hydrolysates, coupled with molecular size analysis, indicated an organized structural feature of the native polymer, which consists of a repeating structural subunit containing complex branching patterns along the xylan backbone and flanked by regions of less complexity. The two lengths of the highly branched subunit were isolated and were shown to have enhanced slow fermentation property compared to the native structure (3.3 vs. 5.9 mL gas, 4 h), that was related to increasing complexity of the branched structures. Lower molecular size structures with higher branch complexity fermented slower, contrary to a conventional view that small fiber structures approaching the oligosaccharide level are necessarily more rapidly fermented.

The Orphan GPCR Receptor, GPR88, Interacts with Nuclear Protein Partners in the Cerebral Cortex.

GPR88 is an orphan G-protein-coupled receptor (GPCR) highly expressed in striatal medium spiny neurons (MSN), also found in cortical neurons at low level. In MSN, GPR88 has a canonical GPCR plasma membrane/cytoplasmic expression, whereas in cortical neurons, we previously reported an atypical intranuclear localization. Molecular size analysis suggests that GPR88, expressed in plasma membrane of MSN or in nuclear compartment of cortical neurons, corresponds to the full-length protein. By transfection of cortical neurons, we showed that GPR88 fluorescent chimeras exhibit a nuclear localization. This localization is contingent on the third intracytoplasmic loop and C-terminus domains, even though these domains do not contain any known nuclear localization signals (NLS). Using yeast two-hybrid screening with these domains, we identified the nuclear proteins ATRX, TOP2B, and BAZ2B, all involved in chromatin remodeling, as potential protein partners of GPR88. We also validated the interaction of GPR88 with these nuclear proteins by proximity ligation assay on cortical neurons in culture and coimmunoprecipitation experiments on cortical extracts from GPR88 wild-type (WT) and knockout (KO) mice. The identification of GPR88 subcellular partners may provide novel functional insights for nonclassical modes of GPCR action that could be relevant in the maturating process of neocortical neurons.

A novel small molecular liquid crystal catalytic amplification-nanogold SPR aptamer absorption assay for trace oxytetracycline

Liquid crystals (LCs) have been applied for a long time in the field of analytical chemistry. To date, there are no reports about utilization of LCs as the catalyst to amplification analytical signal. In this article, three small molecules LCs in water aqueous solutions were characterized using molecular spectra and particle size analysis. The characterization indicated that there are nanoparticles in the system. Among the them, 4-heptylbenzoic acid (HPB) exhibits the most sensitive performance in the analytical system based on the reduction of HAuCl4 to gold nanoparticles (AuNPs) by NaH2PO2 by the spectrophotometric slope evaluation procedure. As the concentration of LCs catalyst increases, the AuNPs surface plasmon resonance (SPR) absorption peak at 550 nm increases linearly, that can be utilized to amply the absorption signal. Based on the LCs catalytic amplification reaction and immunoreaction, a new SPR spectrophotometric analysis method was developed for the label-free detection of oxytetracycline, with a detection limit of 0.50 ng/mL. The method was also successfully applied for the detection of oxytetracycline-spiked environmental water samples to demonstrate its practical usefulness.

Investigation of hierarchically porous zeolitic imidazolate frameworks for highly efficient dye removal

Treatment of textile water containing organic molecules as contaminants still remains a challenge and has become a central issue for environment remediation. Here, a nucleotide incorporated zeolitic imidazolate frameworks (NZIF) featuring hierarchically porous structure served as a potential adsorbent for removal of organic dye molecules. Adsorption isotherms of organic dyes were accurately described by Langmuir adsorption model with correlation coefficients of 0.98 and kinetic data followed the pseudo-second-order model. The maximum adsorption capacity of NZIF for Congo red (CR) and methylene blue (MB) reached 769 and 10 mg/g, respectively, which were 6 and 5 times higher than that of ZIF-8. The adsorption behavior of sunset yellow and crystal violet was examined for mechanism investigation. Analysis of pore size, molecular size, zeta potential and FTIR measurement together revealed that mesopores in NZIF provided more interaction sites and led to enhanced adsorption capacity. Hydrogen bonding and π-π stacking which resulted from the interaction between introduced nucleotide monophosphate and dyes dominated the driving forces for adsorption, where electrostatic interaction was also involved. Moreover, the introduced nucleoside monophosphate enabled NZIF to function under acidic condition whereas ZIF-8 collapsed. This study opens a new avenue for design of porous materials for environment remediation.

Contributions of ethanol fractionation on the properties of vegetable protein hydrolysates and differences in the characteristics of metal (Ca, Zn, Fe)-chelating peptides

Defatted soybean meal, walnut meal, cottonseed meal and wheat gluten flour were hydrolyzed with Alcalase to prepare vegetable protein hydrolysates (VPHs), respectively. Through ethanol fractionation, peptides with lower molecular weight and higher hydrophobicity were enriched in ethanol-soluble VPHs (VPHs-Es), and metal-binding content of VPHs-Es was significantly increased. Zinc and iron were much easier to combine with lower molecular weight peptides (MW < 1 kDa) than calcium. Comparably, ethanol-soluble soybean protein hydrolysates (SPH-Es) had a better metal-binding capacity. The Fourier transform infrared spectra and amino acid composition analysis revealed that the carboxyl oxygen and amino nitrogen were the main binding sites for chelating, and divalent metals had different chelating preferences. The molecular weight distribution, particle size and scanning electron microscope analysis demonstrated significant microstructural differences among the metal (Ca, Zn, Fe) chelates. In particular, obvious aggregation occurred in Ca-SPH-Es, which was induced by hydrogen bonding and electrostatic interaction. Moreover, the gastrointestinal stability of metal chelates was 71.48%, 90.70% and 85.60% for Ca-SPH-Es, Zn-SPH-Es and Fe-SPH-Es, respectively, thus providing a guidance for the exploration of organometallic supplements.

Identification of dissolved organic matter size components in freshwater and marine environments

AbstractDissolved organic matter (DOM) in the transition zone from freshwater to marine systems was analyzed with a new approach for parameterizing the size distribution of organic compounds. We used size‐exclusion chromatography for molecular size analysis and quantified colored DOM (CDOM) on samples from two coastal environments in the Baltic Sea (Roskilde Fjord, Denmark and Gulf of Gdansk, Poland). We applied a Gaussian decomposition method to identify peaks from the chromatograms, providing information beyond bulk size properties. This approach complements methods where DOM is separated into size classes with pre‐defined filtering cutoffs, or methods where chromatograms are used only to infer average molecular weight. With this decomposition method, we extracted between three and five peaks from each chromatogram and clustered these into three size groups. To test the applicability of our method, we linked our decomposed peaks with salinity, a major environmental driver in the freshwater‐marine continuum. Our results show that when moving from freshwater to low‐salinity coastal waters, the observed steep decrease of apparent molecular weight is mostly due to loss of the high‐molecular‐weight fraction (HMW; &gt;2 kDa) of CDOM. Furthermore, most of the CDOM absorbance in freshwater originates from HMW DOM, whereas the absorbing moieties are more equally distributed along the smaller size range (&lt; 2 kDa) in marine samples.

Abstract 2626: Exosomes derived from the BT-20 human breast cancer cell line express E-selectin ligands

Abstract Exosomes are small extracellular vesicles (40-150 nm in diameter) secreted by cells and initially proposed as a mechanism to eliminate cellular waste. More recently, exosomes have been reported to participate in cancer metastasis because of their ability to mediate local and distant cell-to-cell communication. Furthermore, exosomes create cancer-favored microenvironments, potentially enhancing cancer metastasis. However, it is unknown whether exosomes interact with E-selectin, an adhesion molecule expressed by vascular endothelium and shown to be involved in metastasis. Our lab has previously shown that BT-20 human breast cancer cells adhesively interact with endothelial E-selectin via several E-selectin ligands such as sialofucosylated CD44 variants, Mac-2BP, and gangliosides. Therefore, we hypothesize that exosomes secreted by the BT-20 human breast cancer cell line interact with E-selectin. To investigate this hypothesis, exosomes were generated by culturing cells in serum-depleted media and isolated by a series of ultracentrifugation steps. Molecular size analysis using dynamic light scattering revealed that the size range of the isolated particles was similar to the expected size of exosomes. To detect CD9 (an exosome marker) and E-selectin ligands, both breast cancer whole cell lysate and exosome lysate were tested by Western blot. The higher expression of CD9 in isolated particles than the whole cell lysates confirmed that the isolated particles were exosomes. When Western blots were labeled with recombinant E-selectin/Fc chimera with Ca2+, bands were detected at approximately 130 kDa, indicating the presence of E-selectin ligands. As a negative control, the divalent cation chelator EDTA was added to the primary labeling incubation. Bands were not detected in these negative control experiments, indicating no E-selectin interactions in the absence of Ca2+. Human IgG (hIgG) was also used as a negative control in Western blots and showed no signal with exosome lysates, as expected. In comparison, experiments were also performed with Hs578T breast cancer cells, a cell line that our lab has shown does not express E-selectin ligands. Exosomes isolated from Hs578T cells did not express E-selectin ligands, consistent with whole cells. Altogether, these results suggest that BT-20 human breast cancer exosomes express E-selectin ligands. Future work will focus on identifying and characterizing the exosome E-selectin ligands, as well as investigating other cancer cells that express E-selectin ligands. Ultimately, understanding the interaction between exosomes and E-selectin can lead to new diagnostic and therapeutic strategies for cancer metastasis. Citation Format: Yinan Huang, Christian A. Showalter, Monica M. Burdick. Exosomes derived from the BT-20 human breast cancer cell line express E-selectin ligands [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2626.

Abstract 1536: MiRNA expression profile of exosomes derived from breast cancer cells following induction of the epithelial-to-mesenchymal transition

Abstract Breast cancer-derived exosomes are small extracellular vesicles that play a crucial role in the metastatic progression of breast cancer due to their ability to transport a variety of biologically active molecules (e.g., miRNAs) to local and distant sites in the body. The molecular cargo transported by breast cancer-derived exosomes alters the transcriptome of recipient cells at these sites to stimulate pro-metastatic events, including the epithelial-to-mesenchymal transition (EMT). Importantly, the molecular cargo loaded into exosomes can vary depending on cell state. However, it is unclear whether the expression of miRNAs in breast cancer-derived exosomes is altered following inducement of the EMT. Regulation of exosomal miRNAs following the EMT may enhance the ability of circulating tumor cells to target specific tissue sites or improve formation and maintenance of metastatic tumors compared to miRNAs packaged into exosomes secreted from cancer cells without induction of the EMT. To address this knowledge gap, we hypothesized that the EMT alters expression of miRNAs in exosomes derived from EMT-induced MDA-MB-468 breast cancer cells. To induce the EMT, MDA-MB-468 cells were treated with exogenous epidermal growth factor. MDA-MB-468 cells treated with epidermal growth factor exhibited greater mRNA expression of the mesenchymal marker Vimentin compared to non-treated MDA-MB-468 cells by qRT-PCR. Subsequently, exosomes were isolated from the conditioned cell culture medium of MDA-MB-468 cells, with and without induction of the EMT, using ExoQuick exosome isolation reagent. Molecular size analysis of isolated exosomes revealed that they were similar in size to the typical size range reported for exosomes (40 - 150nm). Moreover, a common exosomal marker protein, CD9, was enriched in the MDA-MB-468-derived exosome fractions compared to whole cell lysates by Western blot. Furthermore, next generation sequencing and bioinformatic analysis were performed to determine the miRNA expression profiles of these exosomes. Results from this study reveal expression of miRNAs in breast cancer cell-derived exosomes before and after activation of the EMT and may indicate how exosomes secreted from advanced stage breast cancer enhance metastatic tumor progression. Citation Format: Christian A. Showalter, Yinan Huang, Monica M. Burdick. MiRNA expression profile of exosomes derived from breast cancer cells following induction of the epithelial-to-mesenchymal transition [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1536.

Evaluation of aliphatic/aromatic compounds and fluorophores in dissolved organic matter of contrasting natural waters by SEC-HPLC with multi-wavelength absorbance and fluorescence detections.

The analytical high performance size exclusion liquid chromatography (SEC-HPLC) with multi-wavelength absorbance and fluorescence detections and fluorescence 3D-excitation/emission matrix (EEM) were used for the analysis of average molecular size (MS), molecular size distribution of aliphatic/aromatic compounds and fluorophores in dissolved organic matter (DOM) from Suwannee River (SRDOM) and two Karelian lakes (Vodoprovodnoe Lake - L1DOM and Onego Lake - L2DOM). The average MS of DOM samples varied in the order SRDOM>L1DOM>L2DOM. The absorbance ratios A250/A365 and A210/A254 have been used for the DOM samples characterization. The absorbance ratio A250/A365 provided significant information about average MS of the bulk aquatic DOMs but was not exactly correlated with the results of SEC-HPLC data. The absorbance ratio A210/A254 in combination with SEC was well correlated with the content of DOM aliphatic/aromatic compounds and could be used as an important water quality index to estimate the level of protein-like material in the aquatic DOM. Regardless of the origin (river or lakes), different geographical locations and different average MS of DOM, several similar types of humic-like SEC-separated fluorophores were found within the samples. In all DOM samples the decrease of the fluorophores emission maxima paralleled the decrease of their relative MS. The combination of SEC-HPLC with multi-wavelength fluorescence and absorbance detection and EEM analyses appears very useful for DOM characterization and for tracking of microbial activity resulting from anthropogenic and/or eutrophic impact in aquatic environments.

Characterization of dissolved organic matter in wastewater during aerobic, anaerobic, and anoxic treatment processes by molecular size and fluorescence analyses

Changes in the characteristics of dissolved organic matter (DOM: the dissolved fraction of natural organic matter) during a series of wastewater treatment plant (WWTP) processes were investigated by using a combination of molecular size analysis and excitation emission matrix (EEM) spectroscopy coupled with parallel factor analysis. The characteristics of DOM were compared following aerobic, anoxic, and anaerobic treatments. Three peaks at about 100,000 Da (high-molecular-size DOM, Peak 1) and about 900–1,100 Da (intermediate-molecular-size DOM, Peak 2; low-molecular-size DOM, Peak 3 as the shoulder of Peak 2) were observed in the distribution of total organic carbon molecular sizes in the influent of the WWTPs. In this study, five fluorescent components (C1 to C5) were identified in the EEM spectra. Molecular size analysis and molecular size fractionation revealed that the C3 (humic-like) and C5 (specific to sewage) fluorophores had intermediate or low molecular sizes. Comparison of the changes of the concentrations of dissolved organic carbon in each reaction tank and investigation of the removal selectivity of each treatment (aerobic, anaerobic, and anoxic) suggested that the heterogenous compounds present in DOM of the influent were homogenized into intermediate-molecular-size DOM with high hydrophobicity and aromaticity, or into C4 fluorophores (DOM-X), during anaerobic or anoxic treatment. DOM-X was able to be transformed or removed by aerobic treatment. The results suggested that introduction of aerobic treatment at the appropriate stage of wastewater treatment or inclusion of physical or chemical treatment should be an effective way to optimize DOM removal.

Exosomal Notch3 from high glucose-stimulated endothelial cells regulates vascular smooth muscle cells calcification/aging

AimsVascular calcification/aging can cause different kind of serious diabetic vascular complications. High glucose could induce vascular smooth muscle cells (VSMCs) calcification/aging and then lead to diabetes-related vascular calcification/aging. In this study, we investigated how information in the blood is transmitted to VSMCs and the mechanisms of VSMCs calcification/aging under hyperglycaemic conditions. Materials and methodsTransmission electron microscopy and molecular size analysis were used to assess the morphology and size of exosomes. Alizarin Red S staining and senescence-associated β galactosidase (SA-β-gal) staining were carried out to detect calcification and senescence in VSMCs, respectively. Proteomics analysis was carried out to detect the different expression of exosomal proteins. Protein levels were measured by western blot analysis. Key findingsThe results show that exosomes isolated from high glucose stimulated human umbilical vein endothelial cell (HG-HUVEC-Exo) exhibited a bilayer structure morphology with a mean diameter of 63.63 ± 2.96 nm. The presence of exosome markers including CD9, CD63 and TSG101 were also detected in HG-HUVEC-Exo. High glucose could induce VSMCs calcification/aging by increasing the expression of osteocalcin (OC) and p21 as well as the formation of mineralised nodules and SA-β-gal positive cells. Fluorescence microscopy verified that the exosomes were taken up by VSMCs and Notch3 protein was enriched in HG-HUVEC-Exo. Most importantly, mTOR signalling was closely related to Notch3 protein and was involved in regulating HG-HUVEC-Exo-induced VSMCs calcification/aging. SignificanceThe data demonstrate that Notch3 is required for HG-HUVEC-Exo promoted VSMCs calcification/aging and regulates VSMCs calcification/aging through the mTOR signalling pathway.

Highly Selective Enzymatic Recovery of Building Blocks from Wool-Cotton-Polyester Textile Waste Blends.

In Europe, most of the discarded and un-wearable textiles are incinerated or landfilled. In this study, we present an enzyme-based strategy for the recovery of valuable building blocks from mixed textile waste and blends as a circular economy concept. Therefore, model and real textile waste were sequentially incubated with (1) protease for the extraction of amino acids from wool components (95% efficiency) and (2) cellulases for the recovery of glucose from cotton and rayon constituents (85% efficiency). The purity of the remaining poly(ethylene terephthalate) (PET) unaltered by the enzymatic treatments was assessed via Fourier-transformed infrared spectroscopy. Amino acids recovered from wool were characterized via elementary and molecular size analysis, while the glucose resulting from the cotton hydrolysis was successfully converted into ethanol by fermentation with Saccharomyces cerevisiae. This work demonstrated that the step-wise application of enzymes can be used for the recovery of pure building blocks (glucose) and their further reuse in fermentative processes.

Influence of soluble microbial products on the long-term stability of air cathodes in microbial fuel cells

The practical application of microbial fuel cells (MFCs) is currently restricted by the poor long-term stability of air cathodes, which has proven closely related to the inevitable biofilm growth on catalyst layer. However, the mechanisms how the biofilm inhibits the cathodic oxygen reduction reaction (ORR) remain controversial. This work examined the possible role of soluble microbial products (SMP) of cathode biofilm in fouling of air cathodes. The cathode biofilm SMP were found to primarily consist of polysaccharides, proteins and some humic-like substances. Excitation-emission matrix (EEM), scanning electron microscopy (SEM) and molecular size analyses revealed that the SMP could diffuse into the catalyst layer during MFC operation. Removing SMP from the catalyst layer by chemical cleaning reduced the ohmic resistance (Rohm), charge transfer resistance (Rct) and diffusion resistance (Rd) by 5.3%, 33.3% and 27.7% respectively after 6 months of operation. As a result, the maximum power density of MFCs was increased by 10.2% from 965.1 ± 45.1 mW m−2 to 1063.1 ± 29.5 mW m−2. Impregnating simulated SMP into the catalyst layer increased Rohm, Rct and Rd by 16.8%, 63.6% and 76.2% respectively, resulting in an obvious reduction in the ORR current. These results demonstrated that cathode biofilm SMP are an important factor reducing the long-term stability of air cathodes and thus MFCs, which will be valuable for promoting the practicability of MFCs.

Quantification and characterization of coastal dissolved organic matter by high‐performance size exclusion chromatography with ultraviolet absorption, fluorescence, and total organic carbon analyses

AbstractMolecular size and dissolved organic carbon (DOC) distributions of dissolved organic matter (DOM) in seawater were determined qualitatively and quantitatively by high‐performance size exclusion chromatography (HPSEC). To estimate the relationship between molecular size distribution and the DOC concentration of seawater DOM, seawater was desalinated with an electric dialyzer. The recent technological advancements of desalination make us possible to recover a high percentage of seawater DOM. Surface coastal seawater samples were collected from three locations in Japan: Tokyo Bay, Kashima Port, and Cape Inubo. Samples were evaluated by a chromatography system coupled with ultraviolet (UV) absorbance, fluorescence, and non‐dispersive infrared total organic carbon detectors in series. Two peaks, 1 (1.24 × 105−1.54 × 105 Da) and 2 (9.48 × 102−1.81 × 103 Da), were detected in all sample chromatograms. Peak 1 showed little fluorescence and UV absorption in all samples. It has been shown that carbohydrates, one of the main components of seawater DOM, exhibit almost no fluorescence or UV absorption; thus, Peak 1 could mainly consist of carbohydrates which are usually labile DOM. Total DOC concentrations of the Tokyo Bay, Kashima Port, and Cape Inubo were 1.38, 0.92, and 0.80 mg C L−1, respectively. Peak 2 accounted for 75–80% of the total DOC and showed a substantial humic‐like fluorescence and UV absorption in all samples. These results indicate that the photochemical characteristics of seawater DOM significantly differ depending on its molecular size. Thus, analysis of molecular size with our HPSEC provides a new approach for quantitative and qualitative characterization of seawater DOM.

Synthesis of N-(2 amino benzothiazole) methacylamide monomer and its copolymers for antimicrobial coating application by RAFT polymerization

ABSTRACTMonomer with thiazole moiety was synthesized and copolymerized with butyl acrylate and methyl methacrylate by reversible addition fragmentation chain transfer emulsion polymerization. The chain transfer agent was synthesized using N-ethyl piperazine, carbon disulfide, and ethyl 2-bromoisobutyrate. The wt% of monomer was varied from 3, 5, 7, 9, and 12 respectively. A antimicrobial activities of monomer and its copolymers were screened against E. coli, B. subtilis, C. albicans, and Aspergillus niger microorganisms. The synthesized monomer and chain transfer agent were characterized by 1H NMR, FTIR, and mass spectral analysis, whereas emulsion copolymers were characterized for their molecular weight, particle size, and FTIR analysis.

A study on the reactivity characteristics of dissolved effluent organic matter (EfOM) from municipal wastewater treatment plant during ozonation

The reactivity of dissolved effluent organic matter (EfOM) in the process of ozonation was examined. Under different ozone dosages (0.42 ± 0.09, 0.98 ± 0.11 and 2.24 ± 0.17 mgO3/mg DOC), the EfOM before and after ozonation could be classified into four fractions according to their hydrophobicities. By ozonation, the hydrophobic fractions, especially hydrophobic acid (HOA) and hydrophobic neutral (HON), were found to undergo a process of transformation into hydrophilic fractions (HI), of which the HOA were first transformed into HON, and then the majority of the HON fraction was later converted to HI by further ozonation. It was noticeable that after ozonation, the fluorescence intensity in the humic-like and protein-like regions decreased as indicated by the excitation and emission matrix (EEM) spectra for the hydrophobic fractions. By coupling the EEM spectra with the molecular size analysis using high performance size exclusion chromatography (HPSEC), the difference between the characteristic distributions of the humic-like and protein-like fluorophores were further revealed. It could thus be extrapolated that ozone might have preferentially reacted with the protein-like hydrophobic fraction with molecular weight (MW) less than 100 kDa. Moreover, by X-ray photoelectron spectroscopy (XPS) analysis, it was identified that with increasing ozone dosage (from 0 to 2.24 ± 0.17 mgO3/mg DOC), the aromaticity of HON decreased dramatically, while aliphatics and ketones increased especially at the low ozone dose (0.42 ± 0.09 mgO3/mg DOC). Of the EfOM fractions, the HON fraction would have a higher content of electron enriched aromatics which could preferentially react with ozone rather than the HOA fraction.

Investigation of Lactic Acid Separation by Layered Double Hydroxide: Equilibrium, Kinetics, and Thermodynamics

The layered double hydroxide (LDH) with high crystallinity was prepared via the coprecipitation method for studying the separation equilibria of lactic acid. It was characterized by FTIR, XRD, and molecular size analyses. The effects of the amount of LDH, temperature, and initial lactic acid concentration on the separation process have been investigated. Results show that the maximum removal of lactic acid was obtained as 66.49% in the case of 1 g of LDH at 298 K. The isothermal data were fitted to Langmuir, Freundlich, and Temkin adsorption isotherms. Elovich, Lagergren, and pseudo-second-order kinetic model equations were applied. The experimental data were fitted with the Langmuir isotherm according to R2, which is 0.9894 at 298 K, 0.9972 at 308 K, and 0.9998 at 318 K respectively. Separation depended on initial lactic acid concentration at investigated different temperatures (298 K, 308 K, 318 K) significantly. Standard free energy (ΔGo), enthalpy (ΔHo), and entropy (ΔSo) are calculated. The variation...