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1.
J Biomater Sci Polym Ed ; : 1-15, 2020 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-33218294

RESUMO

Polyurethane nanomicelle is a promising functional drug delivery system. In this work, the polyurethane (P3-PU) was synthesized from PLGA1200-PEG1450-PLGA1200 (P3, a thermosensitive and biodegradable triblock copolymer) and L-lysine ester diisocyanate (LDI). Then, reactive benzaldehyde was further imported to terminate P3-PU to obtain benzaldehyde modified polyurethane (P3-PUDA). The micelles, temperature-sensitive P3-PU nanomicelle and P3-PUDA nanomicelle, were systematically investigated, including the size, stability, temperature sensitivity, drug loading and release behavior, cytotoxic on human hepatocytes (L02), and inhibitory effect on human hepatocellular carcinoma cells (HepG2). The results show the thermosensitive behavior of the micelles can be adjusted by the terminal group. The polyurethane micelles with a uniform size between 20 nm and 30 nm showed excellent stability and good biocompatibility to L02 cells. Besides, in vitro experiments showed that Dox-loaded P3-PUDA micelles exhibited faster and higher release rate at 37 °C and better inhibitory effect on HepG2 than the Dox-loaded P3-PU micelles. Moreover, the achieved benzaldehyde modified polyurethanes also provides various possibilities to adjust further to enlarge its applications. Therefore, the polyurethane micelles will have great potential in the field of drug carriers.

2.
J Mater Chem B ; 2020 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-33242318

RESUMO

Nerve injuries in the central or peripheral nervous system threaten human health and hinder social development, and effectively repairing or regenerating nerve tissues remains a huge challenge. The rise of tissue engineering strategies has brought new light for this. Similar to the extracellular matrix, biomimetic three-dimensional (3D) porous scaffolds can provide biophysical and biochemical cues to guide cell behaviors and support tissue growth. Here, we prepared a hybrid cobalt-doped alginate/waterborne polyurethane 3D porous scaffold with nano-topology of a "coral reef-like" rough surface via two-step freeze-drying. The experimental results demonstrated that the "coral reef-like" rugged surface topology and bioactive cobalt dopant synergistically promote the neurite outgrowth and up-regulate the synaptophysin expression of neuron-like cells PC12 on the scaffold. Furthermore, the scaffold notably relieved the inflammatory response of microglial cells BV2 with the transformation from pro-inflammatory (M1) to anti-inflammatory (M2) phenotype. We believe that this 3D porous scaffold offers bright design inspiration for neural tissue engineering scaffolds and holds potential applications in nerve repair.

3.
Artigo em Inglês | MEDLINE | ID: mdl-33211664

RESUMO

In this paper, we developed an end-to-end basecaller, SACall, based on convolution layers, transformer self-attention layers and a CTC decoder. In SACall, the convolution layers are used to downsample the signals and capture the local patterns. To achieve the contextual relevance of signals, self-attention layers are adopted to calculate the similarity of the signals at any two positions in the raw signal sequence. Finally, the CTC decoder generates the DNA sequence by a beam search algorithm. We use a benchmark consisting of nine isolate genomes for testing the quality of different basecallers including SACall, Albacore, and Guppy. The performances of basecallers are evaluated from the perspective of read accuracy, assembly quality, and consensus accuracy. Among most of the genomes in the test benchmark, the reads basecalled by SACall have fewer errors than the reads basecalled by other basecallers. When assembling the basecalled reads of each genome, the assembly from reads basecalled by SACall achieves a higher assembly identity. In addition, there are fewer errors in the polished assembly from reads basecalled by SACall compared to those basecalled by Albacore and Guppy.

4.
World J Microbiol Biotechnol ; 36(12): 188, 2020 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-33241509

RESUMO

Cyanobacterial blooms are a worldwide problem, especially in freshwaters. As one of the most abundant co-existing organisms of algae, bacteria play critical roles in cyanobacteria growth, particularly the cyanobactericidal bacteria which can efficiently kill cyanobacteria. Recent years, cyanobactericidal bacteria are highly recognized as a method that could potentially block cyanobacterial blooms. Many studies have been conducted to assess their effects on the termination of cyanobacteria blooms and explore their cyanobactericidal mechanisms, e.g., attacking by cell to cell or releasing specific compounds, the physiological, metabolic, and transcriptional disturbance on cyanobacteria. In this review, the present state of research on cyanobactericidal bacteria for the bloom-causing cyanobacteria species is summarized. The challenges in applying cyanobactericidal bacteria in the control of natural cyanobacterial blooms are discussed.

5.
Fungal Biol ; 124(11): 932-939, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-33059845

RESUMO

Sclerotium rolfsii (teleomorph Athelia rolfsii) is one of the plant pathogenic basidiomycetes, which causes severe stem-rot disease in hundreds of plants and produces important metabolites, such as scleroglucan and TF-specific lectin. However, further molecular biological research on this filamentous fungus is severely plateaued out due to the lack of genetic methods. In this study, the A. tumefaciens strain LBA4404 harboring a binary vector containing the basta resistance gene fused with three reporters (DsRed, tdTomato, and GUSPlus) respectively, driven by the SrGPD promoter, was used for genetic transformation of S. rolfsii. The results showed that the three reporter genes were all effectively expressed in S. rolfsii. This study also showed that the intron of the SrGPD promoter is not necessary for transgene expression in this fungus. Besides, we showed that these reporters' signals could be observed easily but in a short time window. The efficient Agrobacterium-mediated transformation system and the three reporter gene plasmids for S. rolfsii developed in this study are of significance in overcoming current limitations of no available transformation and genetic manipulation techniques in S. rolfsii, facilitating further genetic manipulations and gene function exploration.

6.
Artigo em Inglês | MEDLINE | ID: mdl-32944858

RESUMO

Lanthanum molybdate/magnetite (M-La2(MoO4)3) with various LaCl3/Fe3O4 mass ratios was synthesized and optimized for selective phosphate removal from wastewater. M-La2(MoO4)3 (2:1) was selected on the basis of phosphate sorption capacity for further experiments and characterized by a variety of methods. The phosphate sorption kinetics, isotherms, and matrix effect were studied. The maximum sorption capacity at initial pH 7 indicates the possible applicability M-La2(MoO4)3 (2:1) in removing phosphate from the aquatic environment. Phosphate removal by M-La2(MoO4)3 (2:1) with high selectivity was achieved in the presence of other co-existing anions, while calcium and magnesium ions were found to inhibit the sorption process. The sorption isotherm study showed that Freundlich and Sips models fit better the Langmuir model, indicating that heterogeneous multilayer sorption was dominant during the phosphate sorption process. Sorption kinetic results showed that the pseudo-first-order kinetic model can describe well the phosphate sorption process by M-La2(MoO4)3 (2:1). Consecutive sorption-desorption runs showed that M-La2(MoO4)3 (2:1) could be reused for a few cycles. Simultaneous removal of phosphate and organic matter was achieved in real wastewater by using M-La2(MoO4)3 (2:1). The sorption mechanism was inner-sphere complexation.

7.
Inorg Chem ; 59(16): 11793-11800, 2020 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-32799512

RESUMO

Obtaining highly valuable Xe from air or other sources is highly important but still seriously restricted by its inherent inert nature and the great difficulty in separation from other inert gases, especially for Xe and Kr that show comparable size. In this work, we show both experimental and theoretical research of how to boost the selective adsorption of Xe over Kr by double-accessible open-metal site in metal-organic framework (MOF). The MOF, namely, UTSA-74, shows a high Xe uptake up to 2.7 mmol/g and a lower Kr uptake of 0.58 mmol/g at 298 K and 1 bar, leading to a high selectivity of 8.4. The effective Xe/Kr separation was further confirmed by both transient breakthrough simulation and experimental breakthrough. The separation mechanism, as unveiled by the grand canonical Monte Carlo simulation and dispersion-corrected density functional theory calculation, is due to the unique double-accessible open-metal site in UTSA-74 that affords stronger interaction toward Xe than Kr.

8.
Dalton Trans ; 2020 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-32856028

RESUMO

Nuclear power is becoming one of the major clean energies for its high efficiency and low load on the environment. Uranium is a key strategic resource for nuclear power. Uranium reclamation from aqueous systems is of great significance, not only in the usage of nuclear power but also for the remediation of nuclear leakage pollution. Recently, metal-organic frameworks (MOFs) with high porosity, regular pore structure and modifiable functional groups, have been considered as one of the most effective uranium adsorption materials. Specifically, the post-grafted functional groups possess strong affinity to uranium. This frontier summarizes the recent progresses on grafting functional groups in MOFs for U(vi) sorption from aqueous solutions. The adsorption performance, interaction mechanisms and the grafted functional groups are assessed in this study. Finally, personal perspectives on challenges and opportunities are discussed with the hope of supporting and providing some assistance to the designation of MOF-based U(vi) sorption materials.

10.
J Biomater Sci Polym Ed ; 31(17): 2220-2237, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32663417

RESUMO

Compared with the traditional chemotherapy by injection, local release of drugs in the lesion area is a more efficient and less harmful treatment for solid tumors. However, the selection of appropriate drug carrier and controlled release of chemotherapy drugs are still great challenges. Herein, a kind of dual-encapsulated three-dimensional (3D) scaffold is designed for local drug release via blending the paclitaxel (PTX) loaded phospholipid liposomes with waterborne polyurethane (PU) by freeze-drying. The controlled release of paclitaxel is carried out through two simultaneous procedures. First, liposomes encapsulated in polyurethane scaffold can slowly release by water absorption and degradation of polyurethane. Then paclitaxel encapsulated in liposomes can also be released into water. Compared with the polyurethane scaffold which directly encapsulated paclitaxel, dual-encapsulated scaffold has slower initial release amount and maintain higher concentration of paclitaxel in later stage. Moreover, the protection of the phospholipid layer can prevent paclitaxel from being quickly decomposed and cleared, which could greatly improve the bioavailability and therapeutic effect of paclitaxel. Cell experiment results can be seen that dual-encapsulated scaffold not only has higher inhibition rate to the breast cancer MCF7 cells, but also has less damage to normal tissue cells. It provides a more effective platform for the local drug therapy in the treatment of tumors.[Formula: see text].

11.
Int J Biol Macromol ; 163: 1208-1222, 2020 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-32645496

RESUMO

Injectable hydrogels with pH-sensitive and self-healing properties have great application potential in the field of anti-cancer drug carriers. In this work, an injectable hydrogel is prepared using 4armPEG-benzaldehyde (4armPEGDA) and N-carboxyethyl chitosan (CEC) as a new drug carrier. The gelation time, equilibrium swelling rate, degradation time, and dynamic modulus of the injectable hydrogels can be adjusted by merely changing the concentration of 4armPEGDA. The volume of the hydrogel shrinks at pH 5.6 and expands at pH 7.4, which helps to control the release of anti-cancer drug. At pH 5.6, the hydrogels show a fast and substantial Dox release effect, which is five times higher than that at pH 7.4. In vitro cumulative drug release of all the hydrogels reached equilibrium on about the fourth day, and the hydrogel is completely degraded within five days, which contributes to the Dox-loaded hydrogel to further release the remaining Dox. Moreover, the Dox-loaded hydrogel shows a strong inhibitory effect on the growth of human hepatocellular carcinoma cells (HepG2). Finally, the anti-tumor model experiment in vivo demonstrated that the Dox-loaded hydrogel can significantly inhibit tumor growth within five days. Therefore, such injectable hydrogels are excellent carriers for the potential treatment of hepatocellular carcinoma.

12.
Biomater Sci ; 2020 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-32672290

RESUMO

Creating hierarchical polymer brushes possessing antifouling and bactericidal functionalities is a promising approach to combat biomaterial-associated infections. Hence, a well-constructed hierarchical structure is required to achieve optimized antibacterial performance. In this work, contact-killing cationic bactericidal poly(quaternary ammonium salts) (PQAs) bearing different alkyl chain lengths and zwitterionic antifouling poly(sulfobetaine methacrylate) (PSBMA) functional segments were grafted onto an activated substrate via surface-initiated atom transfer radical polymerization (SI-ATRP), and three kinds of polymer brushes with different architectures (Si-PQAs-b-PSBMA, Si-PSBMA-b-PQAs and Si-PQAs-r-PSBMA) were constructed. We demonstrate that the antibacterial effect simultaneously depends on the alkyl chain lengths of PQAs and the hierarchical structure of cationic/zwitterionic segments in polymer brushes. When the polymer brushes composed of a bactericidal bottom layer and an antifouling top layer, the ideal alkyl chain length of PQAs should be eight carbon atoms (Si-PQA8C-b-PSBMA), while in the opposite hierarchical structure, the optimized alkyl chain length of PQAs to synergize with PSBMA was four carbon atoms (Si-PSBMA-b-PQA4C). By appropriately adjusting the alkyl chain length or the hierarchical architecture, the interference between the antifouling and bactericidal functions could be avoided, thus achieving the outstanding long-term antibacterial performance against S. aureus, as well as good hemocompatibility and low cytotoxicity. This work provides fundamental guidance for the design and optimization of efficient and reliable antibacterial surfaces to inhibit biofilm formation.

13.
J Pediatr Nurs ; 55: 1-5, 2020 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-32570090

RESUMO

BACKGROUND: To investigate the effects of different body positions and head elevation angles on regional cerebral oxygen saturation in premature infants using near-infrared spectroscopy (NIRS). METHODS: This was a prospective study of premature infants hospitalized. The position was changed each feeding cycle (2-3 h), in order: 15° prone, 15° supine, 0° prone, and 0° supine position. Regional cerebral oxygen saturation (rSO2) was measured after each position period using NIRS, over 7 days. FINDINGS: Thirty-three premature infants were included in the analysis. Among them, 22 (66.7%) were male, and 11 (33.3%) were female. When placing the premature infants in the prone position, the regional cerebral oxygen saturation (rSO2) values were higher at head elevation 15° compared with 0° (main effect P < 0.001). When placing the premature infants in the supine position, rSO2 was higher at a head elevation of 15° compared with that at 0° (main effect P < 0.001). When placing the premature infants with a head elevation of 15°, rSO2 in the prone position was higher than that of the supine position (main effect P < 0.001). There was no difference between the prone and supine positions when placing the premature infants with the head elevation at 0° (P > 0.05). DISCUSSION: Higher cerebral rSO2 can be achieved when placing premature infants in the prone or supine position, with a 15° head elevation angle. APPLICATION TO PRACTICE: Using a specific body position and head angle could improve the regional cerebral oxygen saturation of premature infants.

14.
Nat Commun ; 11(1): 3163, 2020 06 22.
Artigo em Inglês | MEDLINE | ID: mdl-32572030

RESUMO

Separation of C2H4 from C2H4/C2H2/C2H6 mixture with high working capacity is still a challenging task. Herein, we deliberately design a Th-metal-organic framework (MOF) for highly efficient separation of C2H4 from a binary C2H6/C2H4 and ternary C2H4/C2H2/C2H6 mixture. The synthesized MOF Azole-Th-1 shows a UiO-66-type structure with fcu topology built on a Th6 secondary building unit and a tetrazole-based linker. Such noticeable structure, is connected by a N,O-donor ligand with high chemical stability. At 100 kPa and 298 K Azole-Th-1 performs excellent separation of C2H4 (purity > 99.9%) from not only a binary C2H6/C2H4 (1:9, v/v) mixture but also a ternary mixture of C2H6/C2H2/C2H4 (9:1:90, v/v/v), and the corresponding working capacity can reach up to 1.13 and 1.34 mmol g-1, respectively. The separation mechanism, as unveiled by the density functional theory calculation, is due to a stronger van der Waals interaction between ethane and the MOF skeleton.

15.
Nanotechnology ; 31(38): 385704, 2020 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-32498044

RESUMO

In this work, amorphous Fe-Co-P films prepared by electrodeposition are found to exhibit dense microstructures with amorphous grains. Through a pulse electrodeposition synthesis route, complex microstructures containing nano-sized grains are obtained in the amorphous alloy films. The nanostructured Fe-Co-P amorphous alloys show superior soft magnetic and magnetocaloric properties as compared with those of other iron-based soft magnetic amorphous alloys reported to date. The coercive field of samples can be as small as 1.6 Oe at room temperature. The magnetocaloric effect (MCE) of the ternary amorphous alloys has been investigated by evaluating the magnetic entropy changes, |ΔSM |, from their temperature-dependent magnetization behaviors. The |ΔSM| values are as high as 1.846 J kg-1 K-1 with an applied magnetic field of 10 kOe. With a temperature span of 90 K, the refrigerant capacity of samples can be as high as 118.64 J kg-1. The nanostructure enabled giant MCE in Fe-Co-P amorphous alloys is discussed.

16.
Aust J Rural Health ; 28(3): 271-280, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32558026

RESUMO

OBJECTIVE: China faces issues associated with urban-rural health inequities. This study explores functions of village health centres through a community perspective. Four research questions were asked, including: (a) What are the functions of village health centres? (b) How is medication administered in village health centres? (c) What are the roles of village doctors? (d) What are the evaluation mechanisms of village health centres? DESIGN: In-depth interviews and field observations are used in the study. SETTING: Nine rural villages in two provinces in Northern and Central China. PARTICIPANTS: A total of 93 people across were interviewed. RESULTS: Village health centres are primarily responsible for providing public health services and essential medical care. In addition, village health centres also function as a social venue of a rural community. A centralised medication scheme augments these processes through supplying health centres with affordable medications. Village doctors are expected to take the needs and preferences of their patients into consideration when creating care plans, and must establish trusting rapport with patients by upholding their unique values. This results in care that is convenient, accessible, and person-centred. Village health centres are evaluated through a 2-step process which has direct effects on the amount of government subsidy received. CONCLUSION: Village health centres have multi-faceted functions in rural Chinese communities. Overall, the benefits of village health centres include convenient and timely access to care for rural residents. Improvements can be made in certain areas, such as streamlining provincial medication schemes and adopting a strengths-based model of evaluation.

17.
Nat Commun ; 11(1): 2643, 2020 05 26.
Artigo em Inglês | MEDLINE | ID: mdl-32457390

RESUMO

Amyloid aggregation of α-synuclein (α-syn) is closely associated with Parkinson's disease (PD) and other synucleinopathies. Several single amino-acid mutations (e.g. E46K) of α-syn have been identified causative to the early onset of familial PD. Here, we report the cryo-EM structure of an α-syn fibril formed by N-terminally acetylated E46K mutant α-syn (Ac-E46K). The fibril structure represents a distinct fold of α-syn, which demonstrates that the E46K mutation breaks the electrostatic interactions in the wild type (WT) α-syn fibril and thus triggers the rearrangement of the overall structure. Furthermore, we show that the Ac-E46K fibril is less resistant to harsh conditions and protease cleavage, and more prone to be fragmented with an enhanced seeding capability than that of the WT fibril. Our work provides a structural view to the severe pathology of the PD familial mutation E46K of α-syn and highlights the importance of electrostatic interactions in defining the fibril polymorphs.


Assuntos
Proteínas Mutantes/química , Proteínas Mutantes/genética , Doença de Parkinson/genética , Doença de Parkinson/metabolismo , alfa-Sinucleína/química , alfa-Sinucleína/genética , Acetilação , Sequência de Aminoácidos , Substituição de Aminoácidos , Amiloide/química , Amiloide/genética , Amiloide/ultraestrutura , Microscopia Crioeletrônica , Humanos , Microscopia de Força Atômica , Modelos Moleculares , Proteínas Mutantes/ultraestrutura , Mutação de Sentido Incorreto , Conformação Proteica , Estabilidade Proteica , Eletricidade Estática , alfa-Sinucleína/ultraestrutura
18.
J Mater Chem B ; 8(20): 4434-4446, 2020 05 27.
Artigo em Inglês | MEDLINE | ID: mdl-32367107

RESUMO

Currently, implanting tissue engineering scaffolds is one of the treatment methods for the regeneration of damaged tissues. The matching of the degradation rate of the scaffolds with the regeneration rate of the damaged zone is a big challenge in tissue engineering. Here, we have synthesized a series of biodegradable waterborne polyurethane emulsions and fabricated three-dimensional (3D) connected porous polyurethane scaffolds by freeze-drying. The degradation rate of the scaffolds was controlled by adjusting the relative ratio of poly-ε-caprolactone (PCL) and poly(lactic-co-glycolic acid) (PLGA) in the soft segment. The degradation rate of the scaffolds gradually accelerated with the increase of the relative proportion of PLGA. By co-culture with BV2 microglia, the scaffolds promoted the differentiation of BV2 into an anti-inflammatory M2 phenotype rather than a pro-inflammatory M1 phenotype as the proportion of PLGA increases. When the BV2 cells were stimulated with lipopolysaccharide (LPS), the scaffolds with a higher PLGA ratio showed a much stronger anti-inflammatory effect. Then, we demonstrated that the scaffolds could promote the PC12 neurons to differentiate into neurites. Therefore, we believe that the polyurethane scaffolds have a promising potential application in neural tissue repair.

19.
J Mater Chem B ; 8(23): 5117-5130, 2020 06 21.
Artigo em Inglês | MEDLINE | ID: mdl-32412029

RESUMO

Biodegradable shape memory polymers have great potential for use in minimally invasive surgical procedures. Herein, a series of shape memory polyurethanes (SMPUs) containing a chymotrypsin-inspired chain extender with adjustable mechanical properties and excellent shape memory effect (SME) was prepared successfully. The chemical structure, mechanical properties, SME and in vitro degradation of the PUs were systematically characterized by proton nuclear magnetic resonance spectroscopy, tensile testing, dynamic mechanical analysis under controlled force mode, and scanning electronic microscopy. By increasing the molecular weight of poly(ε-caprolactone) (PCL) and hard segment content, a PCL4000-based SMPU with a modulus value of 115 MPa was obtained, which is three times that of a PCL2000-based sample. Further, the modulus of the PCL4000-based SMPU was increased by 50% while that of the PCL2000-based SMPU was significantly reduced when temperature increased from 23 °C to 37 °C. In addition, the PCL4000-based SMPU exhibited excellent SME with the shape fixity ratio and recovery ratio almost reaching 100%. Gold nanorods were further incorporated into the PU matrix, endowing the materials with a fast near-infrared (NIR) response in 23 s for shape recovery (NIR wavelength of 808 nm, 1.5 W). Combined with enzymatic degradability, these PU/gold-nanorod composites exhibit great potential to be used in biodegradable shape memory expanding stents.

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