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1.
Artigo em Inglês | MEDLINE | ID: mdl-32069009

RESUMO

Delamination of coating layer from polymer substrate limits the lifetime and functionality of the protective films. Silicone coating is especially vulnerable to photo irradiation, hydrothermal degradation, and mechanical deformation due to the low interfacial adhesion and mechanical robustness. Herein, an ingenious approach is developed to fabricate ultrastable and durable silicone coating on polycarbonate (PC) substrate through well-controlled nanoscale interfacial engineering. A nanopillar array is fabricated on the PC surface by vacuum-assisted hot embossing using anodic aluminum oxide (AAO) templates. Significant improvement in interfacial shear strength (ISS) is achieved for the silicone coating on the nanostructured PC surface. The delamination mechanism can be controlled by tuning the nanopillar size, and the maximum ISS of 9.9 MPa was reached on a surface with a nanopillar diameter of 320 nm. Attributed to the increased interfacial area and mechanical interlocking structure, the nanostructured interface can effectively dissipate interfacial stress and prevent cracking; therefore, maintaining excellent transparency and performance in the harsh environment. The coating exhibits extraordinary stability and durability when subjected to UV irradiation for 168 h, hydrothermal aging for 120 h, mechanical bending for 1000 cycles, and even surface damage. Thus, the tough silicone coating on polymer substrate realized by nanoscale interfacial engineering is a promising technique for highly stable and durable transparent surface protection.

2.
Biotechnol Bioeng ; 2020 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-32048725

RESUMO

In the initial step of sugar metabolism, sugar-specific transporters play a decisive role in the passage of sugars through plasma membranes into cytoplasm. The SecY complex (SecYEG) in bacteria forms a membrane channel responsible for protein translocation. The present work shows that permeabilized SecY channels can be used as nonspecific sugar transporters in Escherichia coli. SecY with the plug domain deleted allowed the passage of glucose, fructose, mannose, xylose, and arabinose, and, with additional pore-ring mutations, facilitated lactose transport, indicating that sugar passage via permeabilized SecY was independent of sugar stereospecificity. The engineered E. coli showed rapid growth on a wide spectrum of monosaccharides and benefited from the elimination of transport saturation, improvement in sugar tolerance, reduction in competitive inhibition, and prevention of carbon catabolite repression, which are usually encountered with native sugar uptake systems. The SecY channel is widespread in prokaryotes, so other bacteria may also be engineered to utilize this system for sugar uptake. The SecY channel thus provides a unique sugar passageway for future development of robust cell factories for biotechnological applications.

3.
Animals (Basel) ; 9(5)2019 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-31100843

RESUMO

There is an immune tolerance in maternal immune system during pregnancy, and thymus is a main organ of the immune system. Helper T (Th)1 and Th2 cytokines are involved in the regulation of immune system, but the modulation of Th cytokines in the thymus during early pregnancy is unclear in ewes. Thymuses were collected on day 16 of the estrous cycle, and on days 13, 16, and 25 of pregnancy in ewes. qRT-PCR, Western blot, and immunohistochemistry were used to analyze the expression of Th1 and Th2 cytokines in the thymuses. There was a peak in the expression of interferon-gamma (IFN-γ) on day 16 of pregnancy, an upregulation of tumor necrosis factor beta (TNF-ß), and a sustained expression of interleukin-2 (IL-2) and IL-4. Furthermore, there was a peak in the expression of IL-6 on day 13 of pregnancy, no expression of IL-6 on day 16 of the estrous cycle and day 25 of pregnancy, and an upregulation of IL-5 and IL-10 in the thymuses during early pregnancy. The immunohistochemistry results revealed that the IFN-γ and IL-6 proteins were limited to the stromal cells, capillaries, and thymic corpuscles. In conclusion, early pregnancy influenced the production of Th1 and Th2 cytokines of maternal thymus in sheep.

4.
Sci Rep ; 9(1): 4993, 2019 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-30899065

RESUMO

Photic sneeze reflex (PSR) is an interesting but yet mysterious phenotype featured by individuals' response of sneezing in exposure to bright light. To uncover the underlying genetic markers (single nucleotide polymorphisms, SNPs), a genome-wide association study (GWAS) was conducted exclusively in a Chinese population of 3417 individuals (PSR prevalence at 25.6%), and reproducibly identified both a replicative rs10427255 on 2q22.3 and a novel locus of rs1032507 on 3p12.1 in various effect models (additive, as well as dominant and recessive). Minor alleles respectively contributed to increased or reduced risk for PSR with odds ratio (95% confidence interval) at 1.68 ([1.50, 1.88]) for rs10427255 and 0.65 ([0.58, 0.72]) for rs1032507. The two independent SNPs were intergenic, and collectively enhanced PSR classification by lifting the area-under-curve value in ROC curve to 0.657. Together with previous GWAS in other populations, the result substantiated the polygenic and non-ethnicity-specific nature behind the PSR phenotype.

5.
Mater Sci Eng C Mater Biol Appl ; 98: 241-249, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30813024

RESUMO

Mimicking the mechanical properties of native tissue is an important requirement for tissue engineering scaffolds. Blood vessels are subject to repetitive dilation and contraction and possess a special nonlinear mechanical property due to their triple-layered structure. Fabrication of vascular grafts consisting of bioresorbable materials with biomimetic mechanical properties is an urgent demand, as well as a critical challenge. Inspired by the configuration and function of collagen and elastin in native blood vessels, a new type of triple-layered vascular graft (TLVG) was developed in this study. The TLVGs were composed of braided silk as the inner layer, polyacrylamide (PAM) hydrogel as the middle layer, and electrospun thermoplastic polyurethane (TPU) as the outer layer. The woven-structured silk fibers were able to mimic the properties of the loosely distributed collagen fibers, while the highly elastic PAM hydrogel and TPU nanofibers mimicked the elasticity of elastin in the blood vessel. With this specially designed microstructure and combination of rigid and elastic materials, the TLVGs successfully mimicked the nonlinear mechanical property of native blood vessels. Moreover, TLVGs possess sufficient suture retention strength for surgical implantation. The introduction of a PAM hydrogel layer effectively solved the leaking issue for conventional porous vascular grafts and greatly enhanced the burst pressure. In addition, all materials used have high biocompatibility to human endothelial cells, which indicates that the developed TLVGs have high potential to be used as readily available vascular grafts.


Assuntos
Resinas Acrílicas/química , Nanofibras/química , Poliuretanos/química , Seda/química , Engenharia Tecidual/métodos , Animais , Biomimética , Humanos
6.
ACS Appl Mater Interfaces ; 11(7): 7479-7487, 2019 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-30672685

RESUMO

The severe water contamination caused by oil leakage is calling for low-cost and high-performance absorbent materials for selective oil removal. In this study, a scalable green method was proposed to produce polypropylene (PP)/poly(tetrafluoroethylene) (PTFE) composite foams via conventional processing techniques including twin-screw extrusion and supercritical carbon dioxide foaming. To produce the superhydrophobic foam, micro- and nanosized PTFE particles were melt blended with PP and subsequently foamed. Ascribed to the nanofibrillation of microsized PTFE during processing, the fabricated foam exhibited a special highly porous structure with PTFE nanofibrils and nanoparticles uniformly distributed on the pore surfaces within the PP matrix, which resulted in a remarkably high water contact angle of 156.8° and a low contact angle hysteresis of 1.9°. Unlike traditional surface-modified superhydrophobic absorbers, the foams prepared are entirely superhydrophobic, which means that they remain superhydrophobic when being fractured or cut. Moreover, they are highly durable and maintained the superhydrophobicity when subjected to ultrasonication and mechanical sanding. When used in selective oil absorption, the durable foams exhibited excellent absorption efficiency and high stability in repetitive and long-term use. These advantages make the PP/PTFE foam a promising superabsorbent material for water remediation.

7.
J Biomed Mater Res B Appl Biomater ; 107(7): 2397-2408, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30689292

RESUMO

A mismatch of mechanical properties and a high rate of thromboses are two critical challenges of creating viable artificial small-diameter vascular grafts (SDVGs). Herein, we propose a method to fabricate wavy multicomponent vascular grafts (WMVGs) via electrospinning using an assembled rotating collector. The WMVGs consisted of a wavy silk/poly(lactic acid) (PLA) inner layer and a thermoplastic polyurethane (TPU) outer layer, which mimic the structures and properties of collagen and elastin in native blood vessels, respectively. Attributed to the wavy structure and the combination of rigid silk/PLA and elastic TPU biomaterials, WMVGs are capable of mimicking the nonlinear tensile stress-strain relationship and "toe region" of native blood vessels. In addition, they have sufficient mechanical strength to meet implantation requirements in terms of tensile strength, suture retention, and burst pressure. Further modification of silk/PLA fibers with dopamine and heparin gave the grafts antithrombogenic properties and greatly enhanced endothelial cell affinities. Human umbilical vein endothelial cells (HUVECs) cultured on modified silk/PLA showed high viability, high proliferation rate, and favorable cell-substrate interactions. Moreover, HUVECs were able to fully cover and freely migrate upward on the lumen of the modified WMVGs without needing a special circulation bioreactor. Therefore, the modified WMVGs possessed biomimetic properties, antithrombogenicity, and enhanced endothelialization, making them a promising candidate for SDVGs. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2397-2408, 2019.

8.
Theriogenology ; 123: 177-184, 2019 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-30308394

RESUMO

As a fetal allograft to the mother, early conceptus regulates the intrauterine immune and systemic immune responses during early pregnancy in sheep. However, expression of T helper 1 (Th1) and Th2 cytokines in maternal lymph nodes is unclear during early pregnancy in sheep. In this study, inguinal lymph nodes were obtained on day 16 of the estrous cycle and on days 13, 16 and 25 of pregnancy (n = 4 for each group) in ewes, and qRT-PCR, western blot and immunohistochemistry were used to compare the expression of Th1 and Th2 cytokines in the lymph nodes. Our results showed that there were the highest levels of Th1 cytokines (IFN-γ, TNF-ß and IL-2) and Th2 cytokines (IL-4, IL-5, IL-6 and IL-10) in the lymph nodes on day 13 or 16 of pregnancy. Furthermore, there were a downregulation of TNF-ß and IL-2 and an upregulation of IL-5 and IL-10 on day 25 of pregnancy compared with that in nonpregnancy, with no significant difference in the expression of IFN-γ, IL-4, and IL-6 between the ewes on day 25 of pregnancy and nonpregnancy. The immunohistochemistry results showed that the IL-2 and IL-10 proteins were limited to the subcapsular sinus and trabeculae in the cortex, lymph sinus. In conclusion, early pregnancy exerted its effects on the lymph node and induced a Th2-biased response, which was essential for a normal pregnancy in sheep.


Assuntos
Citocinas/metabolismo , Regulação da Expressão Gênica/fisiologia , Linfonodos/metabolismo , Ovinos/fisiologia , Animais , Citocinas/classificação , Feminino , Gravidez , Prenhez/fisiologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo
9.
Nanoscale ; 10(48): 23131-23140, 2018 Dec 13.
Artigo em Inglês | MEDLINE | ID: mdl-30515502

RESUMO

Boosting power generation performance while employing economical and biocompatible materials is an ongoing direction in the field of triboelectric nanogenerators (TENGs). Here, highly porous, biocompatible, cellulose nanofibril (CNF) composite-based TENGs are developed through an environmentally friendly freeze-drying approach. High tribopositivity materials, including silica fiber, human hair, and rabbit fur, are used as fillers in composite TENG fabrication for the first time to enhance the triboelectric output performance. Among them, a CNF/rabbit fur composite aerogel-based TENG offers the optimum energy generation ability with a high power density of 3.4 W m-2 achieved on a 4.7 MΩ load at a pressure of 30 kPa. Owing to the high output, the porous composite TENG exhibits an excellent energy harvesting performance and high sensitivity in detecting ultralight forces and monitoring human motion when used as a self-powered sensor. This work introduces a new class of highly porous composite TENGs that integrate biocompatibility, low cost, flexibility, high energy generation performance, and sensing sensitivity, as well as providing new strategies for high performance TENG design and fabrication.

10.
Chem Eng J ; 348: 786-798, 2018 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-30455583

RESUMO

Mimicking the mechanical properties of native tissues is a critical criterion for an ideal tissue engineering scaffold. However, most biodegradable synthetic materials, including polyester-based polyurethanes (PUs), consist of rigid polyester chains and have high crystallinity. They typically lack the elasticity of most human tissues. In this study, a new type of biodegradable PU with excellent elasticity was synthesized based on the controlled crosslinking of poly(ester ether) triblock copolymer diols and polycaprolactone (PCL) triols using urethane linkages. Three-dimensional (3D) porous scaffolds with a defined geometry, tunable microstructures, and adjustable mechanical properties were synthesized in situ using an isocyanate-ended copolymer, a tri-armed PCL, and a chain extender. The mechanical properties of the scaffolds can be easily tuned by changing the ratio of reactants, varying the solution concentration, or using a porogen. Notably, all of these scaffolds, although mostly made of rigid PCL chains, showed remarkable elasticity and cyclical properties. With an optimized molecular design, a maximum recovery rate of 99.8% was achieved. This was because the copolymer provided molecular flexibility while the long chain crosslinking of PCL triol hindered crystallization, thus making the PU behave like an amorphous elastic material. Moreover, the in vitro cell culture of 3T3 fibroblasts and MG63 osteoblast-like cells confirmed the biocompatibility of these PU scaffolds and revealed that scaffolds with different stiffnesses can stimulate the proliferation of different types of cells. All of these attributes make PU scaffolds extremely suitable for the regeneration of tissues that experience dynamic loading.

11.
J Mater Chem B ; 6: 3475-3485, 2018 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-30455952

RESUMO

When used as small-diameter vascular grafts (SDVGs), synthetic biomedical materials like polytetrafluoroethylene (PTFE) may induce thrombosis and intimal hyperplasia due to the lack of an endothelial cell layer. Modification of the PTFE in an aqueous solution is difficult because of its hydrophobicity. Herein, aiming to simultaneously promote endothelial cell affinity and antithrombogenicity, a mussel-inspired modification approach was employed to enable the grafting of various bioactive molecules like RGD and heparin. This approach involves a series of pragmatic steps including oxygen plasma treatment, dopamine (DA) coating, polyethylenimine (PEI) grafting, and RGD or RGD/heparin immobilization. Successful modification in each step was verified via Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). Plasma treatment increased the hydrophilicity of PTFE, thereby allowing it to be efficiently coated with dopamine. Grafting of dopamine, RGD, and heparin led to an increase in surface roughness and a decrease in water contact angle due to increased surface energy. Platelet adhesion increased after dopamine and RGD modification, but it dramatically decreased when heparin was introduced. All of these modifications, especially the incorporation of RGD, showed favorable effects on endothelial cell attachment, viability, and proliferation. Due to strong cell-substrate interactions between endothelial cells and RGD, the RGD/heparin-grafted PTFE demonstrated high endothelial cell affinity. This facile modification method is highly suitable for all hydrophobic surfaces and provides a promising technique for SDVG modification to stimulate fast endothelialization and effective antithrombosis.

12.
Theriogenology ; 121: 153-159, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30149261

RESUMO

Interferon-tau (IFNT) is the main signal for the maternal recognition of pregnancy in ruminants, and exerts its effects by stimulating the expression of interferon-stimulated genes, including the expression of interferon-stimulated gene15 kDa protein (ISG15). Progesterone (P4) exerts significant immune effects on the uterus during early pregnancy in ruminants that are partly mediated by progesterone-induced blocking factor (PIBF). The thymus is necessary for the normal development of immunologic function. In this study, thymuses were obtained on day 16 of the estrous cycle and on days 13, 16 and 25 of pregnancy (n = 6 for each group) from ewes. Our results showed that the expression of ISG15, P4 receptor (PGR) and PIBF mRNA and the expression of ISG15 and ISG15-conjugated proteins were upregulated in the thymuses during early pregnancy, and the 89-kDa PGR isoform and the 80-kDa PIBF variant were expressed constantly in the thymuses. However, there was no expression of the 60-kDa PGR isoform and the 62-kDa PIBF variant on day 16 of the estrous cycle. ISG15 and ISG15-conjugated proteins were limited to the epithelial reticular cells, capillaries and thymic corpuscles. This paper reports for the first time that early pregnancy exerts its effects on the thymus through IFNT and P4 in sheep.


Assuntos
Citocinas/metabolismo , Proteínas da Gravidez/metabolismo , Prenhez/genética , Receptores de Progesterona/metabolismo , Ovinos/fisiologia , Fatores Supressores Imunológicos/metabolismo , Animais , Citocinas/genética , Feminino , Regulação da Expressão Gênica , Gravidez , Proteínas da Gravidez/genética , Receptores de Progesterona/genética , Ovinos/metabolismo , Fatores Supressores Imunológicos/genética
13.
ACS Appl Mater Interfaces ; 10(36): 30596-30606, 2018 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-30114352

RESUMO

Triboelectric nanogenerators (TENGs) have been attracting a tremendous amount of attention since their discovery in 2012. Finding new means to enhance energy output is an ongoing pursuit. Herein, we introduce a new type of high-performance TENG composed of highly porous polyamide (PA) nanofiber mats and polyimide aerogel films. We have demonstrated that the thickness of the porous triboelectric materials, which is attained by stacking multiple layers of triboelectric materials, has a profound effect on the triboelectric output performance of TENGs. The triboelectric output increased when PA increased from one layer to six layers. However, it decreased when PA was further increased to 12 layers. With an optimum material thickness, a TENG with only a 2 cm2 effective device size achieved a high output voltage of 115 V and a current of 9.5 µA under a small compressive pressure (30 kPa). A peak power density of 1.84 W/m2 was achieved on a 4.7 MΩ external load. The TENG was able to light 60 light-emitting diodes easily and quickly charge capacitors with different capacitance to 6 V, indicating an outstanding energy harvesting ability. In addition, the performance of multiple TENGs connected in different ways, as well as the performance of TENGs in resistive/inductive/capacitive circuits, were investigated. These findings provide new insight into the working principles of TENGs in complex circuits.

14.
ACS Appl Mater Interfaces ; 10(24): 20897-20909, 2018 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-29863322

RESUMO

Integrating multifunctionality such as adhesiveness, stretchability, and self-healing ability on a single hydrogel has been a challenge and is a highly desired development for various applications including electronic skin, wound dressings, and wearable devices. In this study, a novel hydrogel was synthesized by incorporating polydopamine-coated talc (PDA-talc) nanoflakes into a polyacrylamide (PAM) hydrogel inspired by the natural mussel adhesive mechanism. Dopamine molecules were intercalated into talc and oxidized, which enhanced the dispersion of talc and preserved catechol groups in the hydrogel. The resulting dopamine-talc-PAM (DTPAM) hydrogel showed a remarkable stretchability, with over 1000% extension and a recovery rate over 99%. It also displayed strong adhesiveness to various substrates, including human skin, and the adhesion strength surpassed that of commercial double-sided tape and glue sticks, even as the hydrogel dehydrated over time. Moreover, the DTPAM hydrogel could rapidly self-heal and regain its mechanical properties without needing any external stimuli. It showed excellent biocompatibility and improved cell affinity to human fibroblasts compared to the PAM hydrogel. When used as a strain sensor, the DTPAM hydrogel showed high sensitivity, with a gauge factor of 0.693 at 1000% strain, and was capable of monitoring various human motions such as the bending of a finger, knee, or elbow and taking a deep breath. Therefore, this hydrogel displays favorable attributes and is highly suitable for use in human-friendly biological devices.


Assuntos
Hidrogéis/química , Adesivos , Humanos , Movimento (Física) , Cicatrização
15.
J Biomed Mater Res A ; 106(4): 985-996, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29143442

RESUMO

A new electrospinning approach for fabricating vascular grafts with a layered, circumferentially aligned, and micro-wavy fibrous structure similar to natural elastic tissues has been developed. The customized electrospinning collector was able to generate wavy fibers using the dynamic "jump rope" collecting process, which also solved the sample removal problem for mandrel-type collectors. In this study, natural silk fibroin and synthetic thermoplastic polyurethane (TPU) were combined at different weight ratios to produce hybrid small-diameter vascular grafts. The purpose of combining these two materials was to leverage the bioactivity and tunable mechanical properties of these natural and synthetic materials. Results showed that the electrospun fiber morphology was highly influenced by the material compositions and solvents employed. All of the TPU/fibroin hybrid grafts had mechanical properties comparable to natural blood vessels. The circumferentially aligned and wavy biomimetic configuration provided the grafts with a sufficient toe region and the capacity for long-term usage under repeated dilatation and contraction. Cell culture tests with human endothelial cells (EC) also revealed high cell viability and good biocompatibility for these grafts. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 985-996, 2018.


Assuntos
Materiais Biomiméticos/química , Prótese Vascular , Fibroínas/química , Plásticos/química , Poliuretanos/química , Engenharia Tecidual/métodos , Animais , Bombyx , Células Endoteliais/citologia , Humanos , Solventes , Temperatura Ambiente , Resistência à Tração , Água/química , Molhabilidade
16.
J Mech Behav Biomed Mater ; 78: 433-441, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29227904

RESUMO

The success of blood vessel transplants with vascular scaffolds (VSs) highly depends on their structure and mechanical properties. The fabrication of small diameter vascular scaffolds (SDVSs) mimicking the properties of native blood vessels has been a challenge. Herein, we propose a facile method to fabricate thermoplastic polyurethane (TPU)/polycaprolactone (PCL) hybrid SDVSs via electrospinning using a modified rotating collector. By varying the ratio between the TPU and the PCL, and changing the electrospinning volume, SDVSs with a wavy configuration and different properties could be obtained. Detailed investigation revealed that certain TPU/PCL hybrid SDVSs closely resembled the mechanical behaviors of blood vessels due to the presence of a wavy region and the combination of flexible TPU and rigid PCL, which mimicked the properties of elastin and collagen in blood vessels. The fabricated TPU/PCL SDVSs achieved lumen diameters of 1-3mm, wall thicknesses of 100-570µm, circumferential moduli of 1-6MPa, ultimate strengths of 2-8MPa, over 250% elongation-at-break values, toe regions of 5.3-9.4%, high recoverability, and compliances close to those of human veins. Moreover, these TPU/PCL SDVSs possessed sufficient suture retention strength and burst pressure to fulfill transplantation requirements and maintain normal blood flow. Human endothelial cell culture revealed good biocompatibility of the scaffolds, and cells were able to grow on the inner surface of the tubular scaffolds, indicating promising prospects for use as tissue-engineered vascular grafts.


Assuntos
Eletricidade , Fenômenos Mecânicos , Poliésteres/química , Poliuretanos/química , Rotação , Tecidos Suporte/química , Enxerto Vascular , Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologia , Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Humanos , Relação Estrutura-Atividade
17.
J Mater Chem B ; 5(22): 4137-4151, 2017 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-29170715

RESUMO

Biodegradable synthetic polymers have been widely used as tissue engineering scaffold materials. Even though they have shown excellent biocompatibility, they have failed to resemble the low stiffness and high elasticity of soft tissues because of the presence of massive rigid ester bonds. Herein, we synthesized a new thermoplastic polyurethane elastomer (CTC-PU(BET)) using poly ester ether triblock copolymer (polycaprolactone-block-polytetrahydrofuran-block-polycaprolactone triblock copolymer, PCTC) as the soft segment, aliphatic diisocyanate (hexamethylene diisocyanate, HDI) as the hard segment, and degradable diol (bis(2-hydroxyethyl) terephthalate, BET) as the chain extender. PCTC inhibited crystallization and reduced the melting temperature of CTC-PU(BET), and BET dramatically enhanced the thermal decomposition and hydrolytic degradation rate when compared with conventional polyester-based biodegradable TPUs. The CTC-PU(BET) synthesized in this study possessed a low tensile modulus and tensile strength of 2.2 MPa and 1.3 MPa, respectively, and an elongation-at-break over 700%. Meanwhile, it maintained a 95.3% recovery rate and 90% resilience over ten cycles of loading and unloading. In addition, the TPU could be electrospun into both random and aligned fibrous scaffolds consisting of major microfibers and nanobranches. 3T3 fibroblast cell culture confirmed that these scaffolds outperformed the conventional biodegradable TPU scaffolds in terms of substrate-cellular interactions and cell proliferation. Considering the advantages of this TPU, such as ease of synthesis, low cost, low stiffness, high elasticity, controllable degradation rate, ease of processability, and excellent biocompatibility, it has great prospects to be used as a tissue engineering scaffold material for soft tissue regeneration.

18.
ACS Appl Mater Interfaces ; 9(43): 37529-37535, 2017 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-29035037

RESUMO

Superwettable materials have gained tremendous attention because of their special wetting abilities. The key to obtaining and tuning superwettability is to precisely control the interfacial microstructures and surface energies of materials. Herein, we propose a novel approach to controlling the superwettability of three-dimensional foams. The surface microstructure was manipulated by the layer-by-layer covalent grafting of multidimensional nanoparticles (e.g., silica, carbon nanotubes, and graphene oxide), and the surface energy was tailored by grafting chemicals with different functional groups. This grafting approach improved the mechanical performance, reduced particle loading, and prevented particle disassociation, thereby increasing the absorption capacity and durability of the functionalized foams. More importantly, superhydrophobic/superoleophilic foams were obtained after heptanol grafting. They showed water contact angles of 153° in air and 158° in oil, an absorption capacity 113 times their weight gain, and a remarkable flux of 32.6 L m-2 s-1 for the separation of oil from water driven by gravity. Polydopamine grafting resulted in superhydrophilic/underwater superoleophobic foams that had an oil contact angle of 152° under water and a high flux of 19.3 L m-2 s-1 for the separation of water from oil. Thus, this study offers not only intelligent materials for versatile oil/water separation but also a profound approach for engineering high-performance superwettable materials.

19.
Anim Reprod Sci ; 186: 77-84, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28947097

RESUMO

Progesterone (P4) regulates reproductive and immune functions through binding to the progesterone receptor (PGR), and the effects of P4 are partly mediated by a progesterone-induced blocking factor (PIBF). Bone marrow (BM) is a key component of the lymphatic system and has an important role in immune response. In this study, BM was harvested from femurs on days 13, 16 and 25 of pregnancy and day 16 of the estrous cycles without mated by intact rams, and a qRT-PCR assay, Western blot and an immunohistochemistry analysis were used to analyze the expression of PGR and PIBF genes in BM. The results showed that there was an increase in relative abundance of PGR and PIBF mRNA in BM during early pregnancy, and PGR-B and the full-length PIBF genes were up-regulated in pregnant ewes. Immunohistochemistry results confirmed that the PGR and PIBF proteins were localized in both the cytoplasm and nuclei of adipocytes and the cells in the stroma and capillaries. This is the first study reporting an up-regulated expression of PGR-B and full-length PIBF genes in BM during early pregnancy in sheep. It is suggested that the conceptus exerted its effects on the adipocytes and the cells in the stroma and capillaries in BM, which were involved in the immunoregulation of BM through both cytosolic and nuclear pathways in ewes.


Assuntos
Medula Óssea/metabolismo , Proteínas da Gravidez/metabolismo , Prenhez , Receptores de Progesterona/metabolismo , Ovinos/fisiologia , Fatores Supressores Imunológicos/metabolismo , Animais , Feminino , Regulação da Expressão Gênica/fisiologia , Gravidez , Proteínas da Gravidez/genética , Prenhez/fisiologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Receptores de Progesterona/genética , Fatores Supressores Imunológicos/genética
20.
Mater Sci Eng C Mater Biol Appl ; 72: 53-61, 2017 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-28024618

RESUMO

In this work, three-dimensional poly(caprolactone) (PCL) tissue engineering scaffolds were prepared by co-extrusion and gas foaming. Biocompatible hydroxyapatite (HA) and halloysite nanotubes (HNT) were added to the polymer matrix to enhance the mechanical properties and bioactivity of the composite scaffolds. The effects of HA and HNT on the rheological behavior, microstructure, and mechanical properties of the composite scaffolds were systematically compared. It was found that the HNT improved viscosity more significantly than HA, and reduced the pore size of scaffolds, while the mechanical performance of PCL/HNT scaffolds was higher than PCL/HA scaffolds with the same filler content. Human mesenchymal stem cells (hMSCs) were used as the cell model to compare the biological properties of two composite scaffolds. The results demonstrated that cells could survive on all scaffolds, and showed a more flourishing living state on the composite scaffolds. The cell differentiation for 5% HA and 1% HNT scaffolds were significantly higher than other scaffolds, while the differentiation of 5% HNT scaffolds was lower than that of 1% HNT scaffolds mainly because of the reduced pore size and pore interconnectivity. Therefore, this study suggested that, with proper filler content and control of microstructure through processing, HNT could be a suitable substitute for HA for bone tissue engineering to reduce the cost and improve mechanical performance.


Assuntos
Silicatos de Alumínio/química , Durapatita/química , Nanotubos/química , Poliésteres/química , Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologia , Regeneração Óssea/efeitos dos fármacos , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Argila , Força Compressiva , Citoesqueleto/efeitos dos fármacos , Humanos , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/efeitos dos fármacos , Células-Tronco Mesenquimais/metabolismo , Porosidade , Reologia , Termogravimetria , Engenharia Tecidual , Tecidos Suporte , Difração de Raios X
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