Degradation of tetracycline wastewater by suspended biochar as carriers in moving bed biofilm reactor.

To improve the removal efficiency of antibiotics in moving bed biofilm reactor, suspended biochar block was prepared by the one-pot process and was used as carriers to construct a reaction device to study the treatment effect of antibiotic wastewater. The characteristics of the hanging biofilm in wastewater were investigated. And the mechanism of biochar as a biological carrier has been studied. The results showed that in the 45-day experiment, the maximum number of biofilms for suspended biochar carriers was twice 3.4 times that of the high-density polyethylene carriers. When 10 mg/L tetracycline was added to the reactor, the removal efficiency of the tetracycline removal rate was 71.85% and the chemical oxygen demand (COD), total nitrogen (TN), and NH4+-N removal efficiency reached to 89.95, 61.91 and 85.47% respectively. Suspension biochar carriers can reduce fluctuations in redox potentials, thereby improving the cellular efficiency of microorganisms. Meanwhile, it inhibits the production of soluble microbial products and extracellular polymers, reduces toxic effects, and enhances the adhesion between microorganisms and carriers. The microbial communities of the two carriers were investigated by high-throughput sequencing techniques. Suspended biochar significantly increased the relative abundance of Hydrogenophaga and Comamonas, and improved the ability of nitrification and denitrification. Comamonas could be responsible for tetracycline degradation.

Printed Stretchable Liquid Metal Electrode Arrays for In Vivo Neural Recording.

The adoption of neural interfacing into neurological diagnosis is severely hampered by the complex, costly, and error-prone manufacturing methods, requiring new fabrication processes and materials for flexible neural interfacing. Here a strategy for fabricating highly stretchable neural electrode arrays based on screen printing of liquid metal conductors onto polydimethylsiloxane substrates is presented. The screen-printed electrode arrays show a resolution of 50 µm, which is ideally applicable to neural interfaces. The integration of liquid metal-polymer conductor enables the neural electrode arrays to retain stable electrical properties and compliant mechanical performance under a significant (≈108%) strain. Taking advantage of its high biocompatibility, liquid metal electrode arrays exhibit excellent performance for neurite growth and long-term implantation. The stretchable electrode arrays can spontaneously conformally come in touch with the brain surface, and high-throughput electrocorticogram signals are recorded. Based on stretchable electrode arrays, real-time monitoring of epileptiform activities can be provided at different states of seizure. The method reported here offers a new fabrication strategy to manufacture stretchable neural electrodes, with additional potential utility in diagnostic brain-machine interfaces.

Fuel-Driven Dissipative Self-Assembly of a Supra-Amphiphile in Batch Reactor.

Dissipative self-assembly is an intriguing but challenging research topic in chemistry, materials science, physics, and biology because most functional self-assembly in nature, such as the organization and operation of cells, is actually an out-of-equilibrium system driven by energy dissipation. In this article, we successfully fabricated an I2-responsive supra-amphiphile by a PEGylated poly(amino acid) and realize its dissipative self-assembly in batch reactor by coupling it with the redox reaction between NaIO3 and thiourea, in which I2 is an intermediate product. The formation and dissipative self-assembly of the supra-amphiphile can be repeatedly initiated by adding the mixture of NaIO3 and thiourea, which herein acts as "chemical fuel", while the lifetime of the transient nanostructures formed by the dissipative self-assembly is easily tuned by altering thiourea concentration in the "chemical fuel". Furthermore, as an application demo, the dissipative self-assembly of the supra-amphiphile is examined to control dispersion of multiwalled carbon nanotubes in water, exhibiting a good performance of organic pollutant removal.

Bifunctional defect mediated direct Z-scheme g-C3N4-x/Bi2O3-y heterostructures with enhanced piezo-photocatalytic properties for efficient tooth whitening and biofilm eradication.

Biofilm-associated dental diseases and tooth discoloration have recently become the major barriers to achieve healthy teeth. However, there are few effective strategies to address these issues. Herein, the piezo-photocatalytic process is first proposed to be applied for biofilm eradication and tooth whitening with well-designed direct Z scheme g-C3N4-x/Bi2O3-y heterostructures. DFT calculation and XPS results verify the formation of direct Z scheme g-C3N4/Bi2O3 heterostructures theoretically and experimentally. Using the direct Z scheme g-C3N4-x/Bi2O3-y heterostructure, excellent piezo-photocatalytic effects for tooth whitening and biofilm removal are achieved. For piezo-photocatalytic degradation of the typical food colorant of indigo carmine the degradation rate constant is about quadruple that of piezocatalytic and 2.6 times of photocatalytic treatment. Tooth whitening experiments indicate that g-C3N4-x/Bi2O3-y could whiten the stained teeth through the synergistic piezo-photocatalysis. In addition, excellent antibacterial performances can be obtained on the g-C3N4-x/Bi2O3-y heterostructure through piezo-photocatalytic treatment. Not only the planktonic S. mutans but also those bacteria embedded in biofilms can be effectively killed. The analyses of the piezo-photocatalytic mechanism indicates that the enhanced piezo-photocatalytic performance of the g-C3N4-x/Bi2O3-y heterostructure could be attributed to the much higher separation efficiency of photoexcited charge carriers, increased production amounts of ROS and superior adsorption ability for bacteria than those with bare semiconductors of g-C3N4-x and Bi2O3-y and those treated only with ultrasonic vibration or irradiation. Biosafety results show that the g-C3N4-x/Bi2O3-y heterostructure is biologically safe and piezo-photocatalytic treatment has no harm the tooth structure, demonstrating the great potential of piezo-photocatalytic effect based new tooth whitening and antibacterial technology in future dental care fields.

In vitro evaluation and finite element simulation of drug release from polydiacetylene-polyethylene glycol stearate nanovesicles.

Vesicles comprised of 10,12-pentacosadiynoic acid (PCDA) were modified, using polyethylene glycol 40 stearate (PEG40S), and crosslinked by ultraviolet (UV) irradiation to create polymerized nanovesicles for sustained drug release. Paclitaxel, a water-insoluble compound widely used in cancer chemotherapy, was used as a model drug to examine the physicochemical stability and release profiles of PCDA/PEG40S nanovesicles. TEM analysis revealed the formation of paclitaxel-encapsulated PCDA/PEG40S nanovesicles of 40 to 200 nm in size. Upon the addition of ethanol, instantaneous releases of paclitaxel in the amount of 28 microg/mL from polymerized PCDA/PEG40S nanovesicles and 108 microg/ml from unpolymerized ones were observed. This suggested the non-complete drug release from polymerized PCDA/PEG40S nanovesicles due to their enhanced physicochemical stability by ultraviolet irradiation-induced polymerization, if compared to unpolymerized ones. An in vitro study demonstrated that an accumulative release of 24.1 +/- 3.1% and 8.1 +/- 1.7% of paclitaxel was obtained within 24 hrs from nanovesicles comprised of PCDA/PEG40S at a 9:1 and 7:3 molar ratio, respectively. A finite element model that considered the diffusion-driven releases and the reversible drug-vesicle interaction captured the sustained release of paclitaxel from polymerized PCDA/PEG40S nanovesicles. PCDA/PEG40S nanovesicles capable of sustained release and with enhanced physicochemical stability thus possess great potential for applications in drug release.

Dissipative self-assembly of a dual-responsive block copolymer driven by a chemical oscillator.

HYPOTHESIS: Coupling stimuli-responsive building blocks with an oscillating reaction is an effective strategy to realize and investigate dissipative self-assembly. More importantly, since there is usually more than one component of which concentration periodically changes in a chemical oscillator, it can be expected that this strategy has the advantage of achieving dissipative self-assembly of the building blocks with dual- or even multi-responsiveness. EXPERIMENTS: We realized the dissipative self-assembly of a pH- and iodine-responsive block copolymer, poly(ethylene oxide)-b-poly(2-vinyl pyridine) (PEO-P2VP), by coupling it with the IO3--SO32--Fe(CN)62- (ISF) oscillator, and investigated its rhythmic self-assembly behavior. Furthermore, we proposed a mechanistic model to simulate the kinetics of the ISF oscillator coupling with different amounts of PEO-P2VP. FINDINGS: Rhythmic core-shell reversal of the polymer micelles formed by PEO-P2VP was found in the ISF oscillator. The mechanistic model we proposed successfully reproduced the experimental oscillation and provided some data on the kinetics of the dual responsive self-assembly of PEO-P2VP. This line of research provided an example of realizing dissipative self-assembly of dual-responsive building blocks, which was seldom reported previously. It once again suggested that coupling with a suitable chemical oscillator is a promising strategy to have an insight into the kinetics of stimuli-responsive self-assembly.

Highly Stretchable Metal-Polymer Conductor Electrode Array for Electrophysiology.

Narrowing the mechanical mismatch between biological tissues (typically soft) and neural interfaces (hard) is essential for maintaining signal quality for the electrical recording of neural activity. However, only a few materials can satisfy all requirements for such electronics, which need to be both biocompatible and sufficiently soft. Here, a highly stretchable electrode array (SEA) is introduced, based on the liquid metal-polymer conductor (MPC), achieving high mechanical flexibility and good cytocompatability for neural interfaces. By utilizing the MPC, the SEA exhibits high stretchability (≈100%) and excellent cycling stability (>400 cycles). The cytocompatability of the SEA can allow for long-term culturing of primary neurons and enable signal recording of primary hippocampal neurons. In the future, the SEA could serve as a reliable and robust platform for diagnostics in neuronal tissues and greatly advance brain-machine interfaces.

Reversible photoswitchable fluorescence in thin films of inorganic nanoparticle and polyoxometalate assemblies.

A novel type of inorganic hybridized ultrathin film consisting of Preyssler-type polyoxometalates K(14)[Na(H(2)O)P(5)W(30)O(110)] (Na-POMs) and CdSe@CdS nanoparticles (NPs) was prepared on the solid substrates by a layer-by-layer assembly technique. The film exhibits reversible fluorescence switching behavior under control of irradiation with either UV light or visible light, which is ascribed to the selective occurrence of fluorescence resonance energy transfer between luminescent NPs and different states of photochromic Na-POMs.

Mechanically Robust, Self-Healing, Polymer Blends and Polymer/Small Molecule Blend Materials with High Antibacterial Activity.

There is a growing demand for antibacterial materials around the world in recent years because they can be used for preventing pathogen infection, which is one of the major threats to human health. However, the mechanical damage of the antibacterial materials may weaken their protective effect since bacteria can invade through the cracks of the material. Therefore, antibacterial materials with self-healing ability, in which the mechanical damage can be spontaneously healed, exhibit better reliability and a longer lifespan. In this article, we prepared a series of low-cost antibacterial polymer blends and polymer/small molecule blend materials with excellent self-healing ability and high mechanical strength by a one-pot reaction under mild conditions. These materials were facilely obtained by blending a tiny amount of commercialized cationic antibacterial chemicals, poly(ethylene imine) (PEI) or cetyltrimethylammonium bromide (CTAB), into a self-healing, mechanically robust polymer, poly(ether-thioureas) (PETU). It can be found that they can effectively kill Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) on their surface. Meanwhile, the distinguished advantages of PETU, including self-healing property, excellent mechanical robustness, recyclability, and transparency, were perfectively maintained. Furthermore, it was shown that their cytotoxicity was satisfactory and their hemolytic activity was insignificant. The above advantages of the blend materials suggested their potential applications in health care, food industry, and environmental hygiene.

Mercaptophenylboronic Acid-Activated Gold Nanoparticles as Nanoantibiotics against Multidrug-Resistant Bacteria.

Multidrug-resistant (MDR) bacteria-induced infections are becoming challenging issues threatening human health and life. Current antibiotics can hardly tackle this problem. Herein, we present a strategy to prepare mercaptophenylboronic acid (MBA)-activated gold nanoparticles (Au NPs) as an antibacterial agent against MDR bacteria. Both Au NPs and MBA cannot serve as antibiotics. However, when MBA attaches on Au NPs, the Au_MBA NPs show potent antibacterial activities against Gram-positive MDR clinical isolates (e.g., MDR Staphyloccocus aureus, MDR S. aureus; MDR Staphyloccocus epidermidis, MDR S. epidermidis). Furthermore, Au_MBA NPs show an extremely high median lethal dose (LD50,i.v., 960 mg/kg), which is much higher than those of most of the clinically used antibiotics. As an application example, we dope Au_MBA NPs with electrospun poly(ε-caprolactone) (PCL)/gelatin nanofibrous membranes as wound dressings, which show striking ability to remedy S. aureus- or MDR S. aureus-infected full-thickness skin wounds on rats. Our study provides a novel strategy for treating MDR bacteria-infected wounds in a simple, low-cost, and efficient way, which holds promise for broad clinical applications.

A promising drug controlled-release system based on diacetylene/phospholipid polymerized vesicles.

A novel polymerized vesicular carrier loaded with paclitaxel was developed by introducing the ultraviolet (UV) cross-linkable 10,12-pentacosadiynoic acid (PCDA) into bilayered phospholipid vesicles with the purpose of improving the physicochemical stability as well as the controlled-release property of liposomes. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) results revealed the enhanced stability of PCDA-polymerized vesicles against Triton X-100. In particular, alteration in PCDA/phospholipids ratios and UV-irradiation time can modulate the cumulative paclitaxel released. For instance, vesicles composed of phospholipids only released 98.0 +/- 2.1% of paclitaxel within 24 h. Over the same time period, 72.0 +/- 5.8%, 43.9 +/- 6.5%, and 20.1 +/- 5.4% of paclitaxel was released from polymerized PCDA/phospholipid vesicles at molar ratios of 1:3, 1:1, and 3:1, respectively. Likewise, by increasing the UV-irradiation time from 20 to 40 min, the cumulative release of paclitaxel from polymerized PCDA/phospholipid vesicles at molar ratio of 1:1 decreased from 90.5 +/- 3.7% to 37.6 +/- 2.3% over a time period of experimental observation of 24 h. The influences of vesicle composition (i.e., PCDA/phospholipids ratio) and UV-irradiation time on the release rates of paclitaxel were further examined by finite element (FE) analyzed using Abaqus. Our results demonstrate that novel polymerized vesicles capable of regulating the release of anticancer drugs such as paclitaxel have been developed.

Preparation of polyelectrolyte multilayer coated microbubbles for use as ultrasound contrast agent.

OBJECTIVE: To prepare and characterize polyelectrolyte multilayer film coated microbubbles for use as ultrasound contrast agent (UCA) and evaluate its effects in ultrasonic imaging on normal rabbit's liver parenchyma. METHODS: Perfluorocarbon (PFC)-containing microbubbles (ST68-PFC) were prepared by sonication based on surfactant (Span 60 and Tween 80). Subsequently, the resulting ST68-PFC microbubbles were coated using oppositely charged polyelectrolytes by microbubble-templated layer-by-layer self-assembly technique via electrostatic interaction. The enhancement effects in ultrasonic imaging on normal rabbit's liver parenchyma were assessed. RESULTS: The obtained microbubbles exhibited a narrow size distribution. The polyelectrolytes were successfully assembled onto the surface of ST68-PFC microbubbles. In vivo experiment showed that polyelectrolyte multilayer film coated UCA effectively enhanced the imaging of rabbit's liver parenchyma. CONCLUSIONS: The novel microbubbles UCA coated with polyelectrolyte multilayer, when enabled more function, has no obvious difference in enhancement effects compared with the pre-modified microbubbles. The polymers with chemically active groups (such as amino group and carboxyl group) can be used as the outermost layer for attachment of targeting ligands onto microbubbles, allowing selective targeting of the microbubbles to combine with desired sites.

A Strategy for Rapid Construction of Blood Vessel-Like Structures with Complex Cell Alignments.

A method is developed that can rapidly produce blood vessel-like structures by bonding cell-laden electrospinning (ES) films layer by layer using fibrin glue within 90 min. This strategy allows control of cell type, cell orientation, and material composition in separate layers. Furthermore, ES films with thicker fibers (polylactic-co-glycolic acid, fiber diameter: ≈3.7 µm) are used as cell-seeding layers to facilitate the cell in-growth; those with thinner fibers (polylactic acid, fiber diameter: ≈1.8 µm) are used as outer reinforcing layers to improve the mechanical strength and reduce the liquid leakage of the scaffold. Cells grow, proliferate, and migrate well in the multilayered structure. This design aims at a new type of blood vessel substitute with flexible control of parameters and implementation of functions.

Highly efficient ablation of metastatic breast cancer using ammonium-tungsten-bronze nanocube as a novel 1064 nm-laser-driven photothermal agent.

Photothermal ablation (PTA) therapy has been viewed as an invasive option for cancer therapy with minimal deconstruction of healthy tissues. In this study, a potent candidate of (NH4)xWO3 nanocube was developed for PTA treatment of metastatic breast cancer in the second near-infrared (NIR) window. It was found that the as-synthesized (NH4)xWO3 nanocube had significant photoabsorption across the whole NIR window of 780-2500 nm and exhibited considerable photo-heat conversion efficiency. Moreover, the as-prepared (NH4)xWO3 nanocube displayed good biocompatibility and high cellular uptake efficiency through endocytosis pathway without nuclei entry. The PTA study employing 1064 nm laser in the second NIR window revealed that (NH4)xWO3 nanocubes induced significant cell necrosis and apoptosis by producing obviously hyperthermia effect inside cancer cells. Using an orthotopicly implanted breast tumor model, it demonstrated that the (NH4)xWO3 nanocube was a promising photothermal agent for effective ablation of solid tumors and suppressing their distant metastasis.

Photothermal ablation cancer therapy using homogeneous CsxWO3 nanorods with broad near-infra-red absorption.

Recently, photothermal ablation therapy (PTA) employing near-infrared radiation (NIR) has been extensively investigated as an emerging modality for cancer management. However, the clinical translation of this promising approach is limited by the lack of PTA agents with broad NIR absorption, low cost and high photothermal conversion efficiency. Herein, we have developed PEGylated homogeneous CsxWO3 nanorods (a mean size ∼69.3 nm × 12.8 nm) with broad photo-absorption (780-2500 nm) as a novel NIR absorbent for PTA treatment of human cancer. The prepared CsxWO3 nanocrystals displayed strong near-infrared optical absorption with a high molar extinction coefficient (e.g. 4.8 × 10(10) M(-1) cm(-1) at 980 nm), thus generated significant amounts of heat upon excitation with near-infrared light. The PTA study in two human carcinoma cell lines (i.e. A549 lung cancer cells and HeLa ovarian cancer cells) demonstrated that CsxWO3 nanorods can efficiently cause cell death via hyperthermia induced lysosome destruction, cytoskeleton protein degradation, DNA damage and thereafter cellular necrosis or apoptosis. Our study also confirmed the migration of healthy cells migrated from unirradiated areas to dead cell cycle, which is essential for tissue reconstruction and wound healing after photodestruction of tumor tissue. The prompted results reported in the current study imply the promising potential of CsxWO3 nanorods for application in PTA cancer therapy.

Novel thrombo-resistant coating based on iron-polysaccharide complex multilayers.

The biocompatibility of iron-polysaccharide complexes has been well-documented. Herein, a stable thrombo-resistant coating was fabricated by consecutive adsorption of Fe (III) and polysaccharides including heparin (Hep) and dextran sulfate (DS) onto various surface by layer-by-layer self-assembly technique via both electrostatic interaction and chemical complexation process. The absorbance at 350 nm increased linearly with the number of Fe3+/Hep multilayer, indicating the formation of multilayer structure and the uniform coating. Compared with (Fe3+/Hep)10, the (Fe3+/DS/Fe3+/Hep)5 coating was more hydrophilic and stable due to the incorporation of DS. The activated partial thromboplastin time (APTT) and platelet adhesion assays showed that both (Fe3+/Hep)10 and (Fe3+/DS/Fe3+/Hep)5 coated surfaces were anticoagulant. The complexing with ferric ions did not compromise the catalytic capacity of heparin to promote antithrombin(III)-mediated thrombin inactivation. Chromogenic assays for heparin activity proved definitively that the inhibition of locally produced thrombin was contributed to the thromboresistance of the surface-bound heparin. The surface with Hep or DS as the outmost layer showed stronger anticoagulant activity than Fe3+, indicating that the outermost layer of the coating played a key role in anticoagulant activity. The utilization of dextran sulfate/heparin surfaces was more advantageous than merely the heparin surface for improving blood-contacting medical devices for long-term usage.

Novel hollow microcapsules based on iron-heparin complex multilayers.

Iron-polysaccharide complex have been extensively utilized in the treatment of iron deficiency anemia for parenteral administration. Herein, a novel iron-heparin complexed hollow capsules with nanoscaled wall thickness have been fabricated by means of alternating deposition of ferric ions (III) (Fe+) and heparin (Hep) onto the surface of submicroscaled (488 nm) and microscaled (10.55 microm) polystyrene latex particles via both electrostatic interaction and chemical complexation processes, followed by dissolution of the cores using tetrahydrofuran. Confocal micrographs and atomic force microscopy (AFM) images prove that iron-heparin complexed submicroscaled hollow capsules keep spherical shapes in solution and even after drying. The activated partial thromboplastin time (APTT) assay shows that complexing with ferric ions do not compromise the catalytic capacity of heparin to promote antithrombin III-mediated thrombin inactivation. The anticoagulant activity value of (Fe3+/Hep)8 capsules is evaluated to be about 95.7 U/mg, indicating that approximately 0.55 mg heparin was in 1 mg powder of submicroscaled (Fe3+/Hep)8 hollow capsules. Compared with the same dosage of heparin, iron-heparin complexed hollow capsules display a more prolonged anticoagulant duration than heparin. All these results reveal that such submicroscaled iron-heparin complexed hollow capsules have application potential as an injectable anticoagulant vehicle.