Name: molecular entanglement and electrospinnability of biopolymers
Uploaded: 2014-09-03T15:45:00.000+00:00
Duration: 7 min 59 s
Description: Watch this Scientific Journal Video about Molecular Entanglement and Electrospinnability of Biopolymers at JoVE.com

Bu çalışma Gıda ve Tarım için USDA Ulusal Enstitüsü, Ulusal Rekabetçi Hibeler Programı, Ulusal Araştırma Girişimi Programı 71.1 FY 2007 tarafından kısmen finanse edilen Alerji ve Enfeksiyon Hastalıkları Hibe sayılı 2007-35503-18392 ve Ulusal Sağlık Enstitüleri, Enstitüsü gibi , R33AI94514-03.

1. İplik Dope Hazırlık <ol><li> Ve bu hesaplamalarda biopolimer tozun nem içeriği dikkate emin olun biopolimer konsantrasyonlarda bir dizi (w / v,% 30,% 0.1) araştırılmalıdır hazırlayın. Her bir konsantrasyon için, 50 ml&#39;lik bir test tüpüne biyopolimerin (nişastası veya pululan) toz tartın. Sulu dimetil sülfoksit (DMSO) çözeltisini ve bir karıştırma çubuğu ilave edin. </li><li> Bir manyetik karıştırıcı ocak üzerine sürekli karıştırılarak kaynar su içine tüp yerleştirin. </li><li> 1 saat sonra, ısı kapatın ve dispersiyon oda sıcaklığına soğumaya bırakın. Dispersiyon daha sonra, reolojik deney ve üretebilmektedir hazırdır. </li></ol> 2. Sabit Kayma Reolojisi <ol><li> Reometresi ısıtın ve 20 ° C de, kademe sıcaklığı ayarlanır. Prob (kullanılan 25 mm koni) ve sahne (plaka) arasındaki boşluğu ayarlayın. </li><li> Sahnenin merkezinde üzerine biopolimer dağılımının Yük 0.41 ml positi ayarlamak için prob düşürmek(25 mm koni için 0.053 mm boşluk) üzerinde. Dağılım eşit boşluk içinde yayılır emin olun. </li><li> Aşağıdaki deneysel parametreleri ile reolojik testi yapın: tarama modu: log, başlangıç ​​hızını: 100 sn -1, son hızı: 0.1 sn -1, on yıl başına çekiyor: 10, yapılmasından önce gecikme: 5 sn, zamanı ölçmek: 10 sn, ölçüsü başına ve tarifi: iki (saat yönünün tersine ve hem de). </li><li> Denemeler electrospinning uygun dağılım konsantrasyonları tahmin reolojik verileri analiz. <ol><li> Polimer konsantrasyonlarının bir fonksiyonu olarak kesme oranlarında karşı görünür kesme viskozitelere çizilir. 0.1 sn için görünür viskozitesi (düşük kesme hızı verileri güvenilir, düşük konsantrasyonlarda, örneğin), gerçek veya ekstrapolasyon değerleri her bir akış eğrisi, yaklaşık sıfır kesme viskoziteleri, η 0 için, 1 -. </li><li> Özgül viskozite hesaplayın: η sp = (η 0 - η s)Η s çözücü viskozitesidir / η s. </li><li> Konsantrasyonunun bir fonksiyonu olarak belirli bir viskozitelere çizilir. Semidilute dolanmamış ve dolaşmış rejimleri tanımlayın. Semidilute dolanmamış rejimi, küçük bir eğim ile, düşük konsantrasyonlu ucundan başlar ve semidilute dolaşmış rejimi dolanmamış rejimi sonrasında daha büyük bir eğime sahiptir. Her iki rejimlerde Fit güç-yasası regresyon modelleri. Güç değerleri log-log arsa üzerinde semidilute dolanmamış ve dolaşmış rejimlerde yamaçları (konsantrasyon bağımlılık) vardır. Yerleştirilmiş iki tane çizginin kesişimi dolanması yoğunluğu C * e. </li></ol></li></ol> 3. Elektroeğirme Parametre Değişimi <ol><li> Örneğin,% 15, Şekil 1 &#39;de gösterildiği gibi. Elektro setup monte uygun bir bileşim dağılımı ile şırınga yükleyin (a / h)% 100 DMSO içinde, bir şırınga pompası üzerine nişastası veya pululan. Pozisyon (yüksek gerilim teli bağlayınıziğne ive). Banyoya topraklama kablosunu (negatif) daldırarak toprağa saf etanol içeren pıhtılaşma banyosu bağlayın. Şırınga iğnesi ve pıhtılaşma banyosu arasındaki mesafeyi ayarlamak için bir laboratuar kriko kullanın. Electrospinning sonra elyaf yüzey toplamak için banyoda bir metal örgü bırakın. </li><li> Aşağıdaki parametre aralıkları içinde biyopolimerin Spin: besleme oranı 0.1 0.4 ml / saat, 5 ila 10 cm arasında iplik mesafe ve gerilim 0 ile 15 kV. <ol><li> 5 cm&#39;lik bir mesafede eğirme ile başlayın. Birinci besleme hızı (0.1 ml / saat) için, iğne ucu sıkıp dispersiyonun şekline yavaş yavaş 0 V dikkate alınız voltajı kadar rampa ve damlatma dispersiyon hızlandırılmış ve daha sonra uzun zaman not edin. </li><li> Küçük bir püskürtme çözeltisi electrospinnability gösteren damla yüzeyinden başlamasina voltajı dikkat edin. Bir sürekli bir biçimde jetle varsa başlatılır, burada voltajı kaydedin. </li><li> Üç Paramete her biri için komple bir aralığı incelemekrs ve not başarılı eğirme koşulları. Ucundan sürekli bir püskürtme olduğunda yalnızca lifleri toplamak. </li></ol></li><li> Toplamaya mahsus bir kaç dakika sonra, saf etanol ile bir elyaf yüzey yıkayın. Vakum altında kurutucu madde ihtiva eden bir desikatör içine elyaf yüzey yerleştirin. </li><li> Tam karakterizasyonu için her biopolimer konsantrasyon için tekrarlayın. </li></ol><img alt="Şekil 1" fo:content-width="5in" src="/files/ftp_upload/51933/51933fig1highres.jpg" width="500" /> Elektro-ıslak eğirme kurulum Şekil 1 şematik çizimi. Biyopolimer dispersiyon, bir şırınga pompası sıkılır. Bir yüksek gerilim DC güç kaynağı künt iğne ve zemin koagülasyon banyosu yüksek voltaj sağlar. Iğne ucundan polimer jet düz bir yolda geçecek ve daha sonra (aka istikrarsızlığı kırbaçlanan) hızlı çırpma yolu geliştirir. 4. Morfolojik Karakterizasyonu<ol><li> Kurutulmuş elyaf mat bir parça kesin ve karbon bandı kullanarak bir SEM kütüğü üzerine hareketsiz. </li><li> SEM aracı haline numune saplama yükleyin ve analiz için görüntüler elde. </li></ol>

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Yazarlar ifşa hiçbir şey olmadığını beyan ederim.

Reolojisi geleneksel fiber sıkma dahil olmak üzere ve 13 electrospinning polimerlerin işlenmesi incelemek için önemli bir araçtır. Devamlı kesme reolojik çalışmaları, konformasyon ve polimer, farklı çözücüler içinde etkileşimlerinde kaynaktan çözülebilir (Şekil 2 ve 3). Biyopolimeri molekülleri birbirleriyle örtüşen için yeterli değil, yüksek konsantrasyonlarda, konsantrasyon bağımlılığı iyi çözücü 3,4 diğer polimerler bildi...

Elektro malzemeler çok çeşitli nano-ölçekli elyaf sürekli mikroskopik olarak üretme kabiliyetine sahip olan bir tekniktir. Bu akademik ve endüstriyel ilgi 1 artan kazanmıştır. Kurulum ve Elektrospinning uygulaması basit gibi görünse de, elyaf özelliklerini electrospinnability tahmin ve kontrol yeteneği bir sorun olmaya devam etmektedir. Nedeni Elektroeğirme işlemini 2 ve süreci, fiber tarafından seyahat, özellikle yolu, 1 kaotik etkileyen pek çok faktör vardır ki aslında yalan olabilir. Genellikle ampirik &quot;bakmak cook-ve-&quot; yaklaşımı potansiyel electrospinnable malzemelerin taranması için kullanılır. Bununla birlikte, elektro işlemi üzerinde daha iyi kontrol ve elde edilen elyaf özelliklerinin gereklidir electrospinnability yöneten mekanizmaların daha iyi anlaşılmasını sağlamak için. Bir dizi araştırmacı, iplik dop içinde polimerlerin molekül dolanması bir bizim için esastır buldukBaşarılı Elektrospinning 3 5 l önkoşuldur. Reolojisi polimer dağılımlarına moleküler yapısını ve etkileşimi araştırmak için güçlü bir araçtır. Örneğin, McKee ve diğ. kloroform / dimetil tereftalat (7/3, h / h) içeren bir çözelti içinde lineer moleküler yapıya ve dallanmış poli (etilen tereftalat-ko-etilen izoftalat) kopolimerleri araştırılmıştır ve polimer konsantrasyonu 2-2.5x olması gerektiğini tespit Başarılı üretebilmektedir 4 dolanması konsantrasyonu. Çünkü biyobozunurluk, biyouyumluluk ve vis-à-vis onların sentetik meslektaşları yenilenebirlik kendi avantajları biyopolimerlerden lifleri şu anda yenilenen ilgi var. Ancak uygulayıcılar ısıl işlem ve alt mekanik özelliklerinde yapısal karmaşıklık, zorluk genellikle kaynaklanan birçok sorunlarla karşı karşıya. Bitki dokularında bulunan nişasta, amon olduğug yeryüzünde en bol ve ucuz biopolimerlerden. Saf nişasta lifleri bir elektro-ıslak-bükme aparatı son 6 tarif edildi kullanılarak imal. Pullulan bazı bakteriler tarafından hücre dışı bir lineer polisakkarittir. (1 → 4) ve (1 → 6) düzenli almaşı glukosidik bağlar yeteneği 7,8 şekillendirme mükemmel lif / film dahil pullulan birkaç ayırıcı özelliklerinin, sorumlu olduğuna inanılmaktadır. Sulu dispersiyondan pullulan liflerin elektro araştırmacılar 9,10 bir dizi bildirilmiştir. Daha önceki yayınlarda iki biyopolimer, nişasta 11 ve pullulan 12 electrospinnability, tartışılmıştır. Bu rapor, bu iki Biyopolimerlerin electrospinnability soruşturmasında reolojik ilkelerini kullanan için protokol gösterilmesine yöneliktir.

<table><tbody><tr><td>Gelose 80 starch</td><td>Ingredion</td><td></td><td>Used as it is</td></tr><tr><td>Pullulan</td><td>Hayashibara Co. Ltd</td><td></td><td>Used as it is</td></tr><tr><td>Dimethyl sulfoxide</td><td>BDH Chemicals</td><td>BDH1115-4LP</td><td></td></tr><tr><td>Ethanol</td><td>VWR International</td><td>89125-172</td><td>200 proof</td></tr><tr><td>Rheometer</td><td>TA Instruments</td><td>ARES&amp;nbsp;</td><td>50 mm cone and plate geometry</td></tr><tr><td>Syringe (10 ml)</td><td>Becton, Dickinson and Company</td><td>309604</td><td>Syringe with Luer-Lok&amp;reg; Tip</td></tr><tr><td>High voltage generator</td><td>Gamma High Voltage Research, Inc.</td><td>ES40P</td><td></td></tr><tr><td>Syringe pump</td><td>Hamilton Company</td><td>81620</td><td></td></tr><tr><td>Environmental scanning electron microscope</td><td>FEI Company</td><td>Quanta 200</td><td>for starch fibers</td></tr><tr><td>Environmental scanning electron microscope</td><td>Phenom-World</td><td>Phenom G2 Pro</td><td>for pullulan fibers</td></tr></tbody></table>

molecular entanglement and electrospinnability of biopolymers

Elektro malzemeler çok çeşitli nano-ölçekli liflere mikro imal etmek için ilginç bir tekniktir. Biyopolimerler için, eğirme dop içindeki kurucu polimerlerin molekül dolanması başarılı bir şekilde üretebilmektedir için önemli bir ön-koşul olduğu bulunmuştur. Reolojisi Biyopolimerlerin moleküler yapısını ve etkileşimi araştırmak için güçlü bir araçtır. Bu raporda, dimetil sülfoksit (DMSO) / su dispersiyonlan gelen iki biyopolimer, nişasta ve pullulan ve electrospinnability değerlendirmek için reoloji kullanılması için protokol göstermektedir. Mikron aralığı için mikron altından ortalama çapları ile iyi bir şekilde oluşturulmuş nişasta ve pullulan lifler elde edilmiştir. Electrospinnability oluşan liflerin görsel olarak veya mikroskopik gözlem ile değerlendirilmiştir. Bunların electrospinnability için dispersiyonların reolojik özelliklerini ilişkilendirerek, tüm seçecek etkiler moleküler konformasyon, moleküler dolanması ve kayma viskozitesi göstermektedirrospinning. Reoloji sadece çözücü sistemi seçimi ve işlem optimizasyonu faydalı değil, aynı zamanda moleküler seviyede lif oluşumu mekanizmasının anlaşılması değildir.

Biyopolimer konsantrasyonu ve çözücü DMSO konsantrasyonunun bir fonksiyonu olarak biyopolimer dispersiyonların akış eğrileri elde edilmiştir. İki temsili verileri saf DMSO çözücüsü içindeki konsantrasyonunun bir fonksiyonu olarak nişasta (Şekil 2A) ve pullulan (Şekil 2B) akış eğrilerini göstermektedir. Belirli viskoziteler, biyopolimer konsantrasyonu nişasta (Şekil 3A ve Şekil 3B pullulan) karşı grafik halinde gösterilmişti...

Watch this Scientific Journal Video about Molecular Entanglement and Electrospinnability of Biopolymers at JoVE.com

Molecular Entanglement and Electrospinnability of Biopolymers

Elektro malzemeler çok çeşitli nano-ölçekli liflere mikroskopik olarak imal etmek için kullanılan bir ilginç bir tekniktir. Eğirme dop içindeki kurucu polimerlerin moleküler dolanması başarılı bir şekilde üretebilmektedir için gereklidir. Biz iki Biyopolimerlerin, nişasta ve pullulan bir electrospinnability değerlendirmek reolojisini kullanan bir protokol mevcut.

Moleküler Dolaşıklık Biyopolimerlerin Electrospinnability

Electrospinning is a fascinating technique to fabricate micro- to nano-scale fibers from a wide variety of materials. For biopolymers, molecular ...

molecular-entanglement-and-electrospinnability-of-biopolymers

Research

JoVE Journal

Bioengineering

13.8K Görüntüleme.  Pennsylvania State University.  Elektro malzemeler çok çeşitli nano-ölçekli liflere mikroskopik olarak imal etmek için kullanılan bir ilginç bir tekniktir. Eğirme dop içindeki kurucu polimerlerin moleküler dolanması başarılı bir şekilde üretebilmektedir için gereklidir. Biz iki Biyopolimerlerin, nişasta ve pullulan bir electrospinnability değerlendirmek reolojisini kullanan bir protokol mevcut. 

Video: Molecular Entanglement and Electrospinnability of Biopolymers

Electrospinning Fundamentals: Optimizing Solution and Apparatus Parameters

Electrospun nanofiber scaffolds have been shown to accelerate the maturation, improve the growth, and direct the migration of cells in vitro. Electrospinning is a process in which a charged polymer jet is collected on a grounded collector; a rapidly rotating collector results in aligned nanofibers while stationary collectors result in randomly oriented fiber mats. The polymer jet is formed when an applied electrostatic charge overcomes the surface tension of the solution. There is a minimum concentration for a given polymer, termed the critical entanglement concentration, below which a stable jet cannot be achieved and no nanofibers will form - although nanoparticles may be achieved (electrospray). A stable jet has two domains, a streaming segment and a whipping segment. While the whipping jet is usually invisible to the naked eye, the streaming segment is often visible under appropriate lighting conditions. Observing the length, thickness, consistency and movement of the stream is useful to predict the alignment and morphology of the nanofibers being formed. A short, non-uniform, inconsistent, and/or oscillating stream is indicative of a variety of problems, including poor fiber alignment, beading, splattering, and curlicue or wavy patterns. The stream can be optimized by adjusting the composition of the solution and the configuration of the electrospinning apparatus, thus optimizing the alignment and morphology of the fibers being produced. In this protocol, we present a procedure for setting up a basic electrospinning apparatus, empirically approximating the critical entanglement concentration of a polymer solution and optimizing the electrospinning process. In addition, we discuss some common problems and troubleshooting techniques.

Electrospinning techniques can create a variety of nanofibrous scaffolds for tissue engineering or other applications. We describe here a procedure to optimize the parameters of the electrospinning solution and apparatus to obtain fibers with the desired morphology and alignment. Common problems and troubleshooting techniques are also presented.

Elektrospinning Temelleri: Optimizasyon Çözümü ve Cihazlar Parametreleri

Electrospun nanofiber scaffolds have been shown to accelerate the maturation, improve the growth, and direct the migration of cells in vitro. ...

Biyomühendislik

Air Filter Devices Including Nonwoven Meshes of Electrospun Recombinant Spider Silk Proteins

Based on the natural sequence of Araneus diadematus Fibroin 4 (ADF4), the recombinant spider silk protein eADF4(C16) has been engineered. This highly repetitive protein has a molecular weight of 48kDa and is soluble in different solvents (hexafluoroisopropanol (HFIP), formic acid and aqueous buffers). eADF4(C16) provides a high potential for various technical applications when processed into morphologies such as films, capsules, particles, hydrogels, coatings, fibers and nonwoven meshes. Due to their chemical stability and controlled morphology, the latter can be used to improve filter materials. In this protocol, we present a procedure to enhance the efficiency of different air filter devices, by deposition of nonwoven meshes of electrospun recombinant spider silk proteins. Electrospinning of eADF4(C16) dissolved in HFIP results in smooth fibers. Variation of the protein concentration (5-25% w/v) results in different fiber diameters (80-1,100 nm) and thus pore sizes of the nonwoven mesh.
Post-treatment of eADF4(C16) electrospun from HFIP is necessary since the protein displays a predominantly &alpha;-helical secondary structure in freshly spun fibers, and therefore the fibers are water soluble. Subsequent treatment with ethanol vapor induces formation of water resistant, stable &beta;-sheet structures, preserving the morphology of the silk fibers and meshes. Secondary structure analysis was performed using Fourier transform infrared spectroscopy (FTIR) and subsequent Fourier self-deconvolution (FSD).
The primary goal was to improve the filter efficiency of existing filter substrates by adding silk nonwoven layers on top. To evaluate the influence of electrospinning duration and thus nonwoven layer thickness on the filter efficiency, we performed air permeability tests in combination with particle deposition measurements. The experiments were carried out according to standard protocols.

Spider silk fibers display extraordinary mechanical properties. Engineered Araneus diadematus Fibroin 4 (eADF4) can be processed into nonwoven meshes using electrospinning. Here, the eADF4 nonwoven meshes are used to improve the performance of air filtering devices.

Electrospun Rekombinant Örümcek İpek Proteinlerin Nonwoven Ağlar dahil Hava Filtresi Cihazları

Based on the natural sequence of Araneus diadematus Fibroin 4 (ADF4), the recombinant spider silk protein eADF4(C16) has been engineered. This highly ...

Fabricating Superhydrophobic Polymeric Materials for Biomedical Applications

Superhydrophobic materials, with surfaces possessing permanent or metastable non-wetted states, are of interest for a number of biomedical and industrial applications. Here we describe how electrospinning or electrospraying a polymer mixture containing a biodegradable, biocompatible aliphatic polyester (e.g., polycaprolactone and poly(lactide-co-glycolide)), as the major component, doped with a hydrophobic copolymer composed of the polyester and a stearate-modified poly(glycerol carbonate) affords a superhydrophobic biomaterial. The fabrication techniques of electrospinning or electrospraying provide the enhanced surface roughness and porosity on and within the fibers or the particles, respectively. The use of a low surface energy copolymer dopant that blends with the polyester and can be stably electrospun or electrosprayed affords these superhydrophobic materials. Important parameters such as fiber size, copolymer dopant composition and/or concentration, and their effects on wettability are discussed. This combination of polymer chemistry and process engineering affords a versatile approach to develop application-specific materials using scalable techniques, which are likely generalizable to a wider class of polymers for a variety of applications.

Two- and three-dimensional superhydrophobic polymeric materials are prepared by electrospinning or electrospraying biodegradable polymers blended with a lower surface energy polymer of similar composition.

Biyomedikal Uygulamalar için Süperhidrofobik Polimer Malzemeler imalatı

Superhydrophobic materials, with surfaces possessing permanent or metastable non-wetted states, are of interest for a number of biomedical and industrial ...

Fabricating Degradable Thermoresponsive Hydrogels on Multiple Length Scales via Reactive Extrusion, Microfluidics, Self-assembly, and Electrospinning

While various smart materials have been explored for a variety of biomedical applications (e.g., drug delivery, tissue engineering, bioimaging, etc.), their ultimate clinical use has been hampered by the lack of biologically-relevant degradation observed for most smart materials. This is particularly true for temperature-responsive hydrogels, which are almost uniformly based on polymers that are functionally non-degradable (e.g., poly(N-isopropylacrylamide) (PNIPAM) or poly(oligoethylene glycol methacrylate) (POEGMA)). As such, to effectively translate the potential of thermoresponsive hydrogels to the challenges of remote-controlled or metabolism-regulated drug delivery, cell scaffolds with tunable cell-material interactions, theranostic materials with the potential for both imaging and drug delivery, and other such applications, a method is required to render the hydrogels (if not fully degradable) at least capable of renal clearance following the required lifetime of the material. To that end, this protocol describes the preparation of hydrolytically-degradable hydrazone-crosslinked hydrogels on multiple length scales based on the reaction between hydrazide and aldehyde-functionalized PNIPAM or POEGMA oligomers with molecular weights below the renal filtration limit. Specifically, methods to fabricate degradable thermoresponsive bulk hydrogels (using a double barrel syringe technique), hydrogel particles (on both the microscale through the use of a microfluidics platform facilitating simultaneous mixing and emulsification of the precursor polymers and the nanoscale through the use of a thermally-driven self-assembly and cross-linking method), and hydrogel nanofibers (using a reactive electrospinning strategy) are described. In each case, hydrogels with temperature-responsive properties similar to those achieved via conventional free radical cross-linking processes can be achieved, but the hydrazone cross-linked network can be degraded over time to re-form the oligomeric precursor polymers and enable clearance. As such, we anticipate these methods (which may be generically applied to any synthetic water-soluble polymer, not just smart materials) will enable easier translation of synthetic smart materials to clinical applications.

Protocols are described for the fabrication of degradable thermoresponsive hydrogels based on hydrazone cross-linking of polymeric oligomers on the bulk scale, microscale, and nanoscale, the latter for preparation of both gel nanoparticles and nanofibers.

Parçalanabilir Thermoresponsive Hydrogels birden fazla uzunluğu ölçeklerde yolu ile reaktif ekstrüzyon, havacilik, kendinden montajlı imalatı ve Electrospinning

While various smart materials have been explored for a variety of biomedical applications (e.g., drug delivery, tissue engineering, bioimaging, etc.), ...

Methods for the Self-integration of Megamolecular Biopolymers on the Drying Air-LC Interface

Living organisms that use water are always prone to drying in the environment. Their activities are driven by biopolymer-based micro- and macro-structures, as seen in the cases of moving water in vascular bundles and moisturizing water in skin layers. In this study, we developed a method for assessing the effect of aqueous liquid crystalline (LC) solutions composed of biopolymers on drying. As LC biopolymers have megamolecular weight, we chose to study polysaccharides, cytoskeletal proteins, and DNA. The observation of biopolymer solutions during drying under polarized light reveals milliscale self-integration starting from the unstable air-LC interface. The dynamics of the aqueous LC biopolymer solutions can be monitored by evaporating water from a one-side-open cell. By analyzing the images taken using cross-polarized light, it is possible to recognize the spatio-temporal changes in the orientational order parameter. This method can be useful for the characterization of not only artificial materials in various fields, but also natural living tissues. We believe that it will provide an evaluation method for soft materials in the biomedical and environmental fields.

A method for the drying-induced self-integration of megamolecular biopolymers on the air-liquid crystalline interface is provided here. This methodology will be useful not only for understanding the macroscopic potentials of biopolymers, but also as an evaluation method for soft materials in biomedical and environmental fields.

Kurutma Hava-LC Arayüz üzerinde Megamolecular Biyopolimerlerin Kendinden entegrasyonu için Yöntemler

Living organisms that use water are always prone to drying in the environment. Their activities are driven by biopolymer-based micro- and ...

DNA Nanotubes as a Versatile Tool to Study Semiflexible Polymers

Mechanical properties of complex, polymer-based soft matter, such as cells or biopolymer networks, can be understood in neither the classical frame of flexible polymers nor of rigid rods. Underlying filaments remain outstretched due to their non-vanishing backbone stiffness, which is quantified via the persistence length (lp), but they are also subject to strong thermal fluctuations. Their finite bending stiffness leads to unique, non-trivial collective mechanics of bulk networks, enabling the formation of stable scaffolds at low volume fractions while providing large mesh sizes. This underlying principle is prevalent in nature (e.g., in cells or tissues), minimizing the high molecular content and thereby facilitating diffusive or active transport. Due to their biological implications and potential technological applications in biocompatible hydrogels, semiflexible polymers have been subject to considerable study. However, comprehensible investigations remained challenging since they relied on natural polymers, such as actin filaments, which are not freely tunable. Despite these limitations and due to the lack of synthetic, mechanically tunable, and semiflexible polymers, actin filaments were established as the common model system. A major limitation is that the central quantity lp cannot be freely tuned to study its impact on macroscopic bulk structures. This limitation was resolved by employing structurally programmable DNA nanotubes, enabling controlled alteration of the filament stiffness. They are formed through tile-based designs, where a discrete set of partially complementary strands hybridize in a ring structure with a discrete circumference. These rings feature sticky ends, enabling the effective polymerization into filaments several microns in length, and display similar polymerization kinetics as natural biopolymers. Due to their programmable mechanics, these tubes are versatile, novel tools to study the impact of lp on the single-molecule as well as the bulk scale. In contrast to actin filaments, they remain stable over weeks, without notable degeneration, and their handling is comparably straightforward.

Semiflexible polymers display unique mechanical properties that are extensively applied by living systems. However, systematic studies on biopolymers are limited since properties such as polymer rigidity are inaccessible. This manuscript describes how this limitation is circumvented by programmable DNA nanotubes, enabling experimental studies on the impact of filament rigidity.

DNA nanotüpler Semiflexible polimerler eğitim için çok yönlü bir araç olarak

Mechanical properties of complex, polymer-based soft matter, such as cells or biopolymer networks, can be understood in neither the classical frame of ...

Melt Electrospinning Writing of Three-dimensional Poly(&#949;-caprolactone) Scaffolds with Controllable Morphologies for Tissue Engineering Applications

This tutorial reflects on the fundamental principles and guidelines for electrospinning writing with polymer melts, an additive manufacturing technology with great potential for biomedical applications. The technique facilitates the direct deposition of biocompatible polymer fibers to fabricate well-ordered scaffolds in the sub-micron to micro scale range. The establishment of a stable, viscoelastic, polymer jet between a spinneret and a collector is achieved using an applied voltage and can be direct-written. A significant benefit of a typical porous scaffold is a high surface-to-volume ratio which provides increased effective adhesion sites for cell attachment and growth. Controlling the printing process by fine-tuning the system parameters enables high reproducibility in the quality of the printed scaffolds. It also provides a flexible manufacturing platform for users to tailor the morphological structures of the scaffolds to their specific requirements. For this purpose, we present a protocol to obtain different fiber diameters using melt electrospinning writing (MEW) with a guided amendment of the parameters, including flow rate, voltage and collection speed. Furthermore, we demonstrate how to optimize the jet, discuss often experienced technical challenges, explain troubleshooting techniques and showcase a wide range of printable scaffold architectures.

This protocol serves as a comprehensive guideline to fabricate scaffolds via electrospinning with polymer melts in a direct writing mode. We systematically outline the process and define the appropriate parameter settings for achieving targeted scaffold architectures.

Üç boyutlu Poly(ε-caprolactone) İskele kontrol edilebilir türleri morfoloji ile Electrospinning yazma doku mühendisliği uygulamaları için erime

This tutorial reflects on the fundamental principles and guidelines for electrospinning writing with polymer melts, an additive manufacturing technology ...

Vapor Phase Deposition of Electroactive Poly(3,4-ethylenedioxythiophene) onto Electrospun Commodity Polymer Nanofibers

This study investigates the preparation of polyacrylonitrile (PAN) nanofibers through electrospinning to create highly porous and strong materials for applications in water purification, electrocatalysis, and biomedicine. The uniformly white PAN nanofiber mats were cut into 2 cm x 2 cm coupons to ensure consistency. After electrospinning, these nanofibers were coated with an electroactive polymer (EAP) using chemical vapor deposition, with iron (III) chloride (FeCl3) serving as an oxidant for polymerizing 3,4-ethylenedioxythiophene (EDOT) into poly(3,4-ethylenedioxythiophene) (PEDOT). The study examined the impact of different FeCl3 concentrations on PEDOT deposition on the PAN coupons. PEDOT deposition led to an increase in coupon weight. Scanning electron microscopy (SEM) revealed increases in the diameter of the nanofibers treated with increasing FeCl3 oxidant concentration, although higher FeCl3&#160;concentrations caused inter-fiber bridging, implying a concomitant decrease in inter-fiber spacing. Energy dispersive X-ray spectroscopy (EDS) was used to confirm the presence of Fe, Cl, and S in the nanofibers, with sulfur content rising with FeCl3&#160;concentration used, suggesting increased PEDOT deposition efficiency with increasing oxidant concentration. Mechanical testing showed that PEDOT-coated PAN fibers had improved tensile strength and toughness in the hydrated state compared to pure PAN nanofibers. These results highlight the crucial role of FeCl3&#160;concentration in influencing the morphology and properties of PAN-PEDOT composites, enhancing their suitability for applications such as water purification, tissue engineering, biosensing, catalysis, and energy storage.

This paper describes a simple technique for coating electrospun PAN nanofibers with electroactive polymers using vapor deposition. The effects of the oxidant FeCl&#8323; on the deposition of poly(3,4-ethylenedioxythiophene) coatings on PAN were investigated to understand and optimize polymer growth, fiber diameter, and overall mechanical strength of the nanofiber mats.

Elektroaktif Poli'nin (3,4-etilendioksitiyofen) Elektroeğrilmiş Emtia Polimer Nanofiberler Üzerine Buhar Fazı Biriktirmesi

This study investigates the preparation of polyacrylonitrile (PAN) nanofibers through electrospinning to create highly porous and strong materials for ...

Kimya

Controlling Electrospun Polymer Morphology for Tissue Engineering Demonstrated Using hepG2 Cell Line

Electrospinning affords researchers the opportunity to fabricate reproducible micro to nanoscale polymer fibers. The 3D fibrous architecture of electrospun polymers is regarded as a structural imitation of the extracellular matrix (ECM). Hence, electrospun fibers fabricated from biocompatible polymers have been widely investigated by tissue engineering researchers for their potential role as an artificial ECM for guiding tissue growth both in vitro and in vivo. All cells are acutely sensitive to their mechanical environment. This has been demonstrated by the discovery of multiple mechanotransduction pathways intrinsically linked to the cytoskeletal actin filaments. The cytoskeleton acts as a mechanical sensor that can direct the functionality and differentiation of the host cell depending on the stiffness and morphology of its substrate. Electrospun fibers can be tuned both in terms of fiber size and morphology to easily modulate the mechanical environment within a fibrous polymer scaffold. Here, methods for electrospinning polycaprolactone (PCL) for three distinct morphologies at two different fiber diameters are described. The morphological fiber categories consist of randomly oriented fibers, aligned fibers, and porous cryogenically spun fibers, with 1 &#181;m and 5 &#181;m diameters. The methods detailed within this study are proposed as a platform for investigating the effect of electrospun fiber architecture on tissue generation. Understanding these effects will allow researchers to optimize the mechanical properties of electrospun fibers and demonstrate the potential of this technology more thoroughly.

<meta charset="utf8"></head><body>HepG2 Hücre Hattı Kullanılarak Gösterilen Doku Mühendisliği için Elektrospun Polimer Morfolojisinin Kontrol Edilmesi

This method provides the means to test different polycaprolactone fiber morphologies and topographies for the purpose of tissue engineering. Small and large fibers are fabricated with random orientations, aligned orientations, and also porous cryogenically electrospun structures and used as platforms for cell culture.