Barnacle cement as surface anchor for "clicking" of antifouling and antimicrobial polymer brushes on stainless steel.

Barnacle cement (BC) was utilized 'beneficially' as a surface anchor on stainless steel (SS) for coupling of functional polymer brushes via "click" reactions in both "grafting-to" and "grafting-from" processes. Ethylene sulfide (ES), propargyl carbonylimidazole (PPC) and azidoethyl carbonylimidazole (AEC) reacted with amine and/or hydroxyl groups in BC to introduce the corresponding thiol, alkyne, and azide groups on SS surfaces (SS-thiol, SS-alkyne, and SS-azide, respectively). Antifouling zwitterionic SS-PMPC surface was prepared by thiol-ene photopolymerization of 2-methacryloyloxyethyl phosphorylcholine (MPC) from the SS-thiol surface. Protein-resistant SS-PPEGMA and protein-adsorbing SS-PPFS surfaces were prepared by coupling of the respective azide-functionalized poly(poly(ethylene glycol)methyl ether methacrylate) (azido-PPEGMA) and poly(2,3,4,5,6-pentafluorostyrene) (azido-PPFS) polymer brushes in azide-alkyne "click" reaction. Antifouling alkyne-functionalized poly(N-hydroxyethyl acrylamide) (alkynyl-PHEAA) and antibacterial alkyne-functionalized poly(2-(methacryloyloxy)ethyl trimethylammonium chloride) (alkynyl-PMETA) polymer brushes were clicked on the SS-azide surface. Adsorption of bovine serum albumin and bacteria fouling of Gram-negative Escherichia coli ( E. coli ) and Gram-positive Staphylococcus epidermidis ( S. epidermidis ) were investigated on the polymer-functionalized SS surfaces. The versatile bioanchor and functional polymer brush coatings are stable in an abiotic aqueous environment for over a month.

Layer-by-layer click deposition of functional polymer coatings for combating marine biofouling.

"Click" chemistry-enabled layer-by-layer (LBL) deposition of multilayer functional polymer coatings provides an alternative approach to combating biofouling. Fouling-resistant azido-functionalized poly(ethylene glycol) methyl ether methacrylate-based polymer chains (azido-poly(PEGMA)) and antimicrobial alkynyl-functionalized 2-(methacryloyloxy)ethyl trimethyl ammonium chloride-based polymer chains (alkynyl-poly(META)) were click-assembled layer-by-layer via alkyne-azide 1,3-dipolar cycloaddition. The polymer multilayer coatings are resistant to bacterial adhesion and are bactericidal to marine Gram-negative Pseudomonas sp. NCIMB 2021 bacteria. Settlement of barnacle ( Amphibalanus (= Balanus ) amphitrite ) cyprids is greatly reduced on the multilayer polymer-functionalized substrates. As the number of the polymer layers increases, efficacy against bacterial fouling and settlement of barnacle cyprids increases. The LBL-functionalized surfaces exhibit low toxicity toward the barnacle cyprids and are stable upon prolonged exposure to seawater. LBL click deposition is thus an effective and potentially environmentally benign way to prepare antifouling coatings.

Functional polymer brushes via surface-initiated atom transfer radical graft polymerization for combating marine biofouling.

Dense and uniform polymer brush coatings were developed to combat marine biofouling. Nonionic hydrophilic, nonionic hydrophobic, cationic, anionic and zwitterionic polymer brush coatings were synthesized via surface-initiated atom transfer radical polymerization (SI-ATRP) of 2-hydroxyethyl methacrylate, 2,3,4,5,6-pentafluorostyrene, 2-(methacryloyloxy)ethyl trimethylammonium chloride, 4-styrenesulfonic acid sodium and N,N'-dimethyl-(methylmethacryloyl ethyl) ammonium propanesulfonate, respectively. The functionalized surfaces had different efficacies in preventing adsorption of bovine serum albumin (BSA), adhesion of the Gram-negative bacterium Pseudomonas sp. NCIMB 2021 and the Gram-positive Staphylococcus aureus, and settlement of cyprids of the barnacle Amphibalanus amphitrite (=Balanus amphitrite). The nonionic hydrophilic, anionic and zwitterionic polymer brushes resisted BSA adsorption during a 2 h exposure period. The nonionic hydrophilic, cationic and zwitterionic brushes exhibited resistance to bacterial fouling (24 h exposure) and cyprid settlement (24 and 48 h incubation). The hydrophobic brushes moderately reduced protein adsorption, and bacteria and cyprid settlement. The anionic brushes were least effective in preventing attachment of bacteria and barnacle cyprids. Thus, the best approach to combat biofouling involves a combination of nonionic hydrophilic and zwitterionic polymer brush coatings on material surfaces.

[Spatiotemporal distribution and multi-source characteristics of microplastics in the soil and water environment of Poyang Lake Wetland, China]. / 鄱阳湖湿地水土环境中微塑料的时空分布及多源性.

The increasing microplastics (MPs) pollution in freshwater wetlands has received global concerns. To investigate the spatiotemporal dynamics of MPs in the wetlands of Poyang Lake, surface water and sediment samples were collected from five rivers entering the lake as well as the confluence of Poyang Lake into the Yangtze River, in both dry and wet seasons. The MPs in water and sediment were extracted by the digestion-filtration method and flotation-separation-digestion-filtration method, respectively. Light microscope, Fourier transform infrared spectroscopy, and scanning electron microscope were used for microplastic characterization. The results showed that the abundance of MPs ranged from 32.1 to 127.3 n·L-1 in water samples, and from 533.3 to 1286.6 n·kg-1 in sediment samples during the wet season. In the dry season, the abundance of MPs ranged from 87.1 to 295.5 n·L-1 in water and from 460.0 to 1368.0 n·kg-1 in sediment. Compared with other freshwater wetlands, Poyang Lake had higher abundance of MPs. There were temporal and spatial differences among regions. The main forms of MPs included beads, fragment, film and fiber, and the corresponding polymer components were mainly polystyrene, polypropy-lene and polyethylene. Beads (35.7% in wet season and 52.0% in dry season) were the main form of MPs in water, while fragment (45.8% in wet season and 69.7% in dry season) was the main form of MPs in sediment. Small size (<0.1 mm) MPs were dominant (>50%) in water and sediment in both seasons. The abundance of MPs with different sizes decreased with the increases of size. The potential main sources of MPs in the wetlands of Poyang Lake included the discharge of industrial wastewater, discharge from urban and rural domestic sewage treatment plants, agricultural and fishing activities, and improper disposal of domestic wastes.

Biomimetic anchors for antifouling and antibacterial polymer brushes on stainless steel.

Barnacle cement (BC) was beneficially applied on stainless steel (SS) to serve as the initiator anchor for surface-initiated polymerization. The amine and hydroxyl moieties of barnacle cement reacted with 2-bromoisobutyryl bromide to provide the alkyl halide initiator for the surface-initiated atom transfer radical polymerization (ATRP) of 2-hydroxyethyl methacrylate (HEMA). The hydroxyl groups of HEMA polymer (PHEMA) were then converted to carboxyl groups for coupling of chitosan (CS) to impart the SS surface with both antifouling and antibacterial properties. The surface-functionalized SS reduced bovine serum albumin adsorption, bacterial adhesion, and exhibited antibacterial efficacy against Escherichia coli (E. coli). The effectiveness of barnacle cement as an initiator anchor was compared to that of dopamine, a marine mussel inspired biomimetic anchor previously used in surface-initiated polymerization. The results indicate that the barnacle cement is a stable and effective anchor for functional surface coatings and polymer brushes.

Synthesis of water-soluble europium-containing nanoprobes via polymerization-induced self-assembly and their cellular imaging applications.

Lanthanide nanoprobes have attracted extensive attention for applications in cellular imaging and biological sensing. Herein, water-dispersible europium (III)-based (Eu(III)-based) nanoprobes were prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization-induced self-assembly (PISA) of hydrophobic monomers (Eu(III)-containing monomer and methyl methacrylate (MMA)) using hydrophilic macro-chain transfer agent poly(PEGMA)-CTA. The resulted poly(PMEu) nanoprobes showed spherical in shape in good monodispersity with average diameters of around 210 nm. The poly(PMEu) nanoprobles excellent aqueous dispersity, high aqueous stability and good luminescence properties with quantum yields of 37.21% and fluorescence lifetime of 312.4 µs. Moreover, the poly(PMEu) nanoprobes exhibited good cellular biocompatibility with cell viabilities of 88.2% and high fluorescence intensity for in vitro cellular imaging. The present approach provides a facile strategy for fabrication of luminescent Eu(III)-based nanoprobes with great potential applications for biological imaging.

A hybrid polyvinyl alcohol/molybdenum disulfide nanosheet hydrogel with light-triggered rapid self-healing capability.

A hybrid self-healing hydrogel (PM hydrogel), based on polyvinyl alcohol (PVA) and chemically exfoliated molybdenum disulfide (ce-MoS2) nanosheets, was prepared by a simple freeze-thaw method. Due to the excellent photothermal conversion properties of ce-MoS2 nanosheets, the PM hydrogel self-repaired rapidly under near infrared (NIR) light irradiation for only 3 min with a high healing efficiency of 91.8 ± 3.3%. The PVA content, ce-MoS2 nanosheet loading and light irradiation time played important roles in the self-healing performance. Additionally, the PM hydrogel also revealed good self-healing properties with a healing efficiency of 60.6 ± 3.6% after the cut surfaces were separated for 24 h. The present approach provides an effective strategy for fabricating fast light-triggered hydrogen-bond based self-healing systems. The as-prepared hybrid PM hydrogel has great potential as a soft biomaterial for long-term applications due to its biocompatibility and self-healing capability.

[Effects of polystyrene microplastics (PS-MPs) on the growth, physiology, and biochemical characteristics of Hydrilla verticillata]. / 聚苯乙烯微塑料对黑藻生长及生理生化特征的影响.

In order to evaluate the effects of polystyrene microplastics (PS-MPs) on the growth, physiology, and biochemical characteristics of submerged plants, we exposed a typical submerged plant, Hydrilla verticillata, to a series of concentrations (i.e. 0, 5, 10, 30, 50, 100 mg·L-1) of 3 µm polystyrene microplastics (PS-MPs) and measured parameters including height, biomass, chlorophyll content, antioxidant enzyme activity, photosynthetic fluorescence. The results showed that the height of H. Verticillata significantly decreased at the high PS-MP concentrations (50 to 100 mg·L-1), while the fresh weight significantly increased at the low PS-MP concentration (5 mg·L-1). The fresh weight of H. verticillata gradually decreased with the increasing PS-MP concentration but the dry weight did not change. The total amount of chlorophyll, chlorophyll a, and chlorophyll a/b significantly decreased with the increases of the PS-MP concentrations, while the chlorophyll b did not change. PS-MPs affected the antioxidant enzyme activities of H. verticillata. The activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) were first increased and then decreased with the increasing PS-MP concentration. The chlorophyll fluorescence parameters (Fo, Fm, Fv/Fm) decreased with the increasing concentration of PS-MP and the 1-Qp-Lss value (reflective of the closing of PSⅡ reaction center) was increased under the stable state, probably due to the inhibited PSⅡ reaction center. The overall intensity of fluorescence imaging of H. verticillata decreased with the increasing concentration of PS-MPs. When the PS-MP concentration was lower than 10 mg·L-1, the photosynthetic activity of the leaves was normal. In contrast, when the PS-MP concentration was higher than 30 mg·L-1, it caused significant adverse effects on leaves, including weaker photosynthetic intensity and the presence of yellow or withered leaves. Our results suggested that H. verticillata could tolerate PS-MP pollution but its growth and photosynthesis would be inhibited at high concentrations (>30 mg·L-1). Our results provided basic information to better understand the eco-physiological effects of PS-MPs in the freshwater environment.

Occurrence, effect, and fate of residual microplastics in anaerobic digestion of waste activated sludge: A state-of-the-art review.

The plastic products have large consumption over last decades, resulting in a serious microplastics (MPs) pollution. Specially, the main removal way of MPs from wastewater is to transfer MPs from liquid to solid phase, leading to its enrichment in waste activated sludge (WAS). Anaerobic digestion has been served as the most potential technique to achieve both resource recovery and sludge reduction, herein this review provides current information on occurrence, effect, and fate of MPs in anaerobic digestion of WAS. The effects of MPs on WAS anaerobic digestion are greatly related to forms, particles sizes, contents, compositions and leachates of MPs. Also, the presence of MPs not only can change the effects of other pollutants on anaerobic digestion of WAS, but also can affect the fates of them. Besides, the future perspectives focused on the fate, effect and final removal of MPs during WAS anaerobic digestion process are outlined.

Versatile functionalization of surface-tailorable polymer nanohydrogels for drug delivery systems.

Surface decoration of nanohydrogels with functional molecules as well as nanomaterials offers a facile approach for developing multifunctional drug nanocarriers. Herein, the surface-tailorable polymer nanohydrogels, with the catechol groups as a universal anchor, were prepared by simple reflux-precipitation polymerization for versatile functionalization as drug delivery systems. The resultant polymer nanohydrogels were not only capable of delivering doxorubicin (DOX) through electrostatic interactions, but also exhibited facile conjugation with magnetic Fe3O4 nanoparticles and anticancer drug bortezomib (BTZ) via the versatile catechol-based coupling chemistry. The DOX and Fe3O4 loaded nanohydrogels (DOX-Fe3O4@NG) exhibited high DOX loading capability and triggered drug release behaviors in the acidic and redox environment. Furthermore, the DOX-Fe3O4@NG achieved improved cellular uptake in the presence of external magnetic field due to the active magnetic targeting properties. As for the dual drug delivery system (DOX-BTZ@NG), the DOX-BTZ@NG also released the drugs in response to the external stimuli including low pH and GSH presence, indicating their intelligent drug delivery properties. In particular, the DOX-BTZ@NG showed higher antiproliferation efficacy to cancer cells in comparison with the single drug loaded nanohydrogels, suggesting a synergistic effect of the dual drug combination therapy. The degradable poly(AA-co-DMA) nanohydrogels with surface-tailorable functionalities are thus a promising versatile platform for conjugation with both nanomaterials and drug molecules.

[Dynamic membrane bioreactor with glass fiber tube covered with organic membrane].

A novel grille form complex membrane module composed of glass fiber covered with organic membrane and the dynamic membrane bioreactor (DMBR) with this complex membrane were studied. The results showed that the flux of the dynamic membrane of glass fiber tube without covering with organic membrane solution was only 4 L/(m2 x h) at a trans-membrane pressure (TMP) of 0.02 MPa. After the modification of covering with the organic membrane solution, the complex dynamic membrane flux could reach to a level of 16 L/(m2 x h) at a TMP of 0.01 MPa in operation, and after a hydraulic and chemical cleaning, the membrane flux was up to 17.1 L/(m2 x h) at a lower TMP of 0.003 MPa. When the glass fiber tube was coated with a membrane solution with a concentration of 1:4 (membrane materials/solution in volume ratio), the flux of the complex membrane worked steadily at 14.29 L/(m2 x h) more than 51 days, and according to calculation by TMP rising, the flux could maintain for almost 275 d. The average removal rates of COD and NH4+ -N were 81.96% and 83.66% respectively by the DMBR, and that were 21.01% and 3.61% only by the complex dynamic membrane. Moreover, the cost of complex membrane was approximately 40-60 yuan/m2, which was lower than the traditional organic membrane.

[Study of a new type of tubular self-forming dynamic membrane bioreactor and its application for treatment of landfill leachate].

A new type of fiberglass tubular self-forming dynamic membrane bioreactor (DMBR) and its application for treatment of landfill leachate on laboratory scale were studied. The results showed that the system worked with a average membrane flux 3.75 L/m2 x h) maintained by gravity filtration at a trans-membrane pressure (TMP) of 2 900 Pa for near 80 days. After the modification of membrane module, a higher membrane flux was achieved at a TMP of 1 450 Pa and the membrane flux could be maintained steadily at 6 L/(m2 x h) for a long time. At the same time, the formation and filtration performance of dynamic membrane (DM) was tested. The effluent turbidity was blow 1.0 NTU and the average removal of COD, BOD5 and NH4(+) -N in this system exceeded 71%, 96% and 98% respectively. Moreover, COD removal from the supernatant on an average of 19.34% was made only by the dynamic membrane.

[An in vitro experiment on the antimicrobial effects of ethanol extract from salvia miltiorrhiza bunge on several oral pathogenic microbes].

PURPOSE: To study the in vitro antimicrobial activity of ethanol extract of salvia miltiorrhiza bunge on several oral pathogenic microbes. METHODS: Antimicrobial activities of ethanol extract of salvia miltiorrhiza bunge for porphyromonas gingivalis ATCC 33277, A. actinomycetes comitans ATCC 24523, Streptococcus mutans, and Lactobacillus were determined using the cup-plate method. The minimum antibacterial concentrations of ethanol extract of salvia miltiorrhiza bunge were measured. SPSS10.0 software package was used for Student's t test. RESULTS: Ethanol extract of salvia miltiorrhiza bunge had antimicrobial activities on Porphyromonas gingivalis, A. actinomycetemcomitans, Streptococcus mutans, Lactobacillus, and the minimum inhibitory concentrations were 15.62 mg/ml, 15.62 mg/ml, 62.50mg/ml and 15.62 mg/ml; The pH of the solution was influential to its antimicrobial activity. CONCLUSION: Ethanol extract of salvia miltiorrhiza bunge has an antimicrobial activity on oral pathogenic microbes.