Polybrominated Diphenyl Ethers in Sediments from Arkansas, Illinois and Indiana of the United States

Sediment samples were collected from Arkansas, Illinois and Indiana of the United States and analyzed for polybrominated diphenyl ethers (PBDEs) and decabromodiphenyl ethane (DBDPE). BDE209 was found at 34,000 and 5,600 ng/g in the surface sediments and peaked at 57,000 and 48,000 ng/g at the two locations nearest to the manufacturing facilities in southern Arkansas, the highest levels ever reported in sediments worldwide. The DBDPE concentrations of 744, 870 and 2,400 ng/g found at the three locations closest to the manufacturing facilities are also the highest in sediment reported to date worldwide. The concentrations of total PBDEs (Σ49BDEs) ranged from 90 to 400 ng/g and from 1,900 to 3,500 ng/g in the surface sediments from Illinois and Indiana, respectively. BDE209 was dominant in the sediments of all locations, accounting for 69-97% of the total PBDEs. The surface concentrations in Arkansas samples versus distances from the sampling locations to manufacturing facilities fitted the Gaussian Plume Dispersion model (R2 of 0.98 for BDE209 and 0.90 for DBDPE). The spatial trends and the temporal trends suggest that the manufacturing facilities were the significant sources of BDE209 and DBDPE found in the sediments in Arkansas. The variation in congener distribution along the sediment depth suggests in situ debromination of BDE209 at one site, particular in upper sediment layers. Two nonabromodiphenyl ethanes (nona-BDPEs) were found at the site with elevated levels relative to DBDPE, suggesting the debromination of DBDPE. In order to understand PBDE debromination pathway, 13 congeners (BDEs 209, 208, 207, 206, 196, 183, 154, 153, 100, 99, 85, 47 and 28) in hexane were individually exposed to natural sunlight with different time segments up to 64 hours. Overall, 74 product congeners were detected. For the reactant congeners with =9 bromines. The total molar mass of PBDEs decreased dramatically during the sunlight exposure, indicating the formation of non-PBDE substances

Emerging Brominated Flame Retardants in the Sediment of the Great Lakes

The concentrations of 13 currently used brominated flame retardants (BFRs) were analyzed in 16 sediment cores collected from the North American Great Lakes. Among them, 1,2-bis­(2,4,6-tribromophenoxy)­ethane (BTBPE), decabromodiphenyl ethane (DBDPE), hexabromocyclododecane (HBCD), 1,2-dibromo-4-(1,2-dibromoethyl)­cyclohexane (TBECH), and hexachlorocyclopentadienyl dibromocyclooctane (HCDBCO) were more frequently detected than others. In general, these emerging BFRs have much lower concentrations than polybromodiphenyl ethers (PBDEs) and dechloranes. Inventories of the five BFRs named above, given on a logarithm basis, were found to decrease linearly with the increasing latitude of the sampling locations, but with weaker statistics than those previously reported for the dechloranes. Logarithm of surface fluxes, on the other hand, was found to be a better parameter in correlating with the longitude. With regard to time trends, the exponential increases in concentrations of these BFRs, particularly DBDPE and BTBPE, in recent years are particularly disturbing. The sediment concentration of DBDPE doubles every 3–5 years in Lake Michigan, and approximately every 7 years in Lake Ontario. The corresponding doubling times for BTBPE are about 5 and 7 years in Lakes Ontario and Michigan, respectively, although declines or leveling off were observed in the top sediment layers in Lake Ontario. In contrast to PCBs, PBDEs, and most dechloranes, the correlations between the surface concentration of emerging BFRs and the latitude or longitude of the sampling sites were not strengthened by normalization of the concentration based on the organic matter content of the sediment

Optimization of Brush-Like Cationic Copolymers for Nonviral Gene Delivery

Polyethylenimine (PEI) is one of the most broadly used polycations for gene delivery due to its high transfection efficiency and commercial availability but materials are cytotoxic and often polydisperse. The goal of current work is to develop an alternative family of polycations based on controlled living radical polymerization (CLRP) and to optimize the polymer structure for efficient gene delivery. In this study, well-defined poly­(glycidyl methacrylate)­(P­(GMA)) homopolymers were synthesized using reversible addition–fragmentation chain transfer (RAFT) polymerization followed by decoration using three different types of oligoamines, i.e., tetraethylenepentamine (TEPA), pentaethylenehexamine (PEHA), and tris­(2-aminoethyl)­amine (TREN), respectively, to generate various P­(GMA-oligoamine) homopolycations. The effect of P­(GMA) backbone length and structure of oligoamine on gene transfer efficiency was then determined. The optimal polymer, P­(GMA-TEPA)₅₀, provided comparable transfection efficiency but lower cytotoxicity than PEI. P­(GMA-TEPA)₅₀ was then used as the cationic block in diblock copolymers containing hydrophilic <i>N</i>-(2-hydroxypropyl) methacrylamide (HPMA) and oligo­(ethylene glycol) monomethyl ether methacrylate (OEGMA). Polyplexes of block copolymers were stable against aggregation in physiological salt condition and in Opti-MEM due to the shielding effect of P­(HPMA) and P­(OEGMA). However, the presence of the HPMA/OEGMA block significantly decreased the transfection efficacy of P­(GMA-TEPA)₅₀ homopolycation. To compensate for reduced cell uptake caused by the hydrophilic shell of polyplex, the integrin-binding peptide, RGD, was conjugated to the hydrophilic chain end of P­(OEGMA)₁₅-<i>b</i>-P­(GMA-TEPA)₅₀ copolymer by Michael-type addition reaction. At low polymer to DNA ratios, the RGD-functionalized polymer showed increased gene delivery efficiency to HeLa cells compared to analogous polymers lacking RGD

Sunflower Polymers for Folate-Mediated Drug Delivery

Polymeric delivery vehicles can improve the safety and efficacy of chemotherapy drugs by facilitating preferential tumor delivery. Polymer–drug conjugates are especially attractive carriers because additional formulation steps are not required during manufacturing, and drug release profiles can be altered based on linker choice. For clinical translation, these vehicles should also be reproducibly and controllably synthesized. Recently, we reported the development of a class of materials called “sunflower polymers,” synthesized by controlled radical polymerization of hydrophilic “petals” from a cyclic multimacroinitiator “core”. This synthesis strategy afforded control over the size of the polymer nanostructures based on their petal polymerization time. In this work, we demonstrate that particle size can be further tuned by varying the degree of polymerization of the cyclic core in addition to that of the petals. Additionally, we investigate the application of these materials for tumor-targeted drug delivery. We demonstrate that folate-targeted, doxorubicin-conjugated sunflower polymers undergo receptor-mediated uptake into cancer cells and pH-triggered drug release leading to cytotoxicity. These materials are attractive as drug carriers due to their discrete and small size, shielded drug cargo that can be triggered for release, and relative ease of synthesis

The phylogenetic tree of strains transforming quercetin.

<p>The phylogenetic tree of strains transforming quercetin.</p

The supernatant broths with quercetin after fermented by different bacteria.

<p>The tubes of 1–7 individually refer to the supernatant broths inoculated with <i>Escherichia coli</i>, <i>Stretococcus lutetiensis</i>, <i>Lactobacillus acidophilus</i>, <i>Weissella confusa</i>, <i>Enterococcus gilvus</i>, <i>Clostridium perfringens</i> and <i>Bacteroides fragilis</i>. Tube 0 is the positive control without any strains and quercetin; tube 8 is the negative control with quercetin but no any strains.</p

K_ATP response to suction.

<p>Current was recorded at −60 mV in symmetrical solutions at the indicated pressures. A: Two data segments of 2.8 min with 2 min of intervening data omitted to show steady state behavior. K_ATP was inhibited by 0.2 mM ATP and activated by suction. B: K_ATP response to pressure ladders. C: Traces a to e show longer term activity and are marked with corresponding letters in B. D: All-points histograms were constructed using the data segments (1.6 sec each) in B at 0, −20 and −40 mm Hg, respectively.</p

Effect of cytoB on the response to pressure steps.

<p>A: Recordings from a patch before and after cytoB treatment. B: Recordings in another patch before and after exposure to phalloidin (10 µM) followed by cytoB (20 µmol/L) (phal+cytoB). C: The semilog plots of <i>NP_o</i>-pressure relationship before and after treatment with cytoB. The two semilog plots are parallel while the intercept is increased by cytoB (n = 6; <i>P</i><0.05) suggesting cytoB increases the background activity only. D: The semilog plots of <i>NP_o</i>-pressure relationship before and after treatment with phalloidin followed by cytoB (phal+cytoB). The two semilog graphs coincides and the increment in background activity induced by cytoB was abolished by application of phalloidin in advance (n = 5; <i>P</i>>0.05).</p

Synthesis and Characterization of Dextran–Tyramine-Based H₂O₂‑Sensitive Microgels

We report a type of polymer microgel that can undergo a rapid and highly sensitive volume change upon adding H₂O₂. Such a H₂O₂-sensitive microgel is made of dextran–tyramine and horseradish peroxidase (HRP), which are interpenetrated in chemically cross-linked gel networks of poly­(oligo­(ethylene glycol) methacrylates). Unlike the H₂O₂-sensitive microgels reported in previous arts that typically involve degradation processes related to H₂O₂-induced cleavability of specific bonds, the proposed microgels can shrink upon adding H₂O₂ owing to the HRP-catalyzed coupling reaction of tyramine residues via decomposition of H₂O₂. While a fast (<10 s) and stable shrinkage of the microgels can be reached upon adding H₂O₂ over a concentration range 50.0 μM–1.0 mM, the response time can be modulated by the dispersion temperature in a nonmonotonous way over 10–38 °C. With the microgels as probes, the H₂O₂ detection limit was approximately 6.8 μM. In a combined use of the microgels with glucose oxidase for glucose detection, the glucose detection limit was approximately 83.1 μM

Isolates, verified and identified strains from three selective media.

<p>Abbreviations: BEA-Bile Esculin Azide Agar, MRS-medium invented by de Man, Rogosa and Sharpe, BHI-Brain Heart Infusion Broth.</p