Presentation on theme: "Electrospinning of Nanofabrics"— Presentation transcript:
1 Electrospinning of Nanofabrics Presented by U6:Pavitra TimbaliaMichael TrevathanJared Walker
2 Outline Introduction Background Current Research Future Research ApparatusGeneral ApplicationsCurrent ResearchFuture ResearchQuestions
3 Introduction Nanofabrics are composed of nonwoven nanofibers Nanofibers are created by a process called electrospinning.Electrospinning is a major way to engineer (without self- assembly) nanostructures that vary in:Fiber DiameterMesh SizePorosityTexturePattern FormationBurger, Christian, et. al. Nanofibrous Materials and Their Applications
4 Introduction Grafts: Woven vs. Nonwoven The nonwoven structure has unique features:Interconnected poresVery large surface-to-volume ratioEnables nanofibrous scaffolds to have many biomedical and industrial applications.(a) Woven fabrics(b) Non-woven fabrics(c) “Soldered” junctionsBurger, Christian, et. al. Nanofibrous Materials and Their Applications
5 An ExampleTake the distance between the Earth and the Moon, L, to be 380,000 km.It takes only x grams of a polymer fiber filament to make up this distanceρ = 1 g cm-3 and the fiber diameter d = 2r = 100 nmX = Vρ = πr2Lρ = π (50 nm)2 (380,000 km) (1 g cm-3 )≈ 3 gramsBurger, Christian, et. al. Nanofibrous Materials and Their Applications
7 Electrospinning - Procedure An electrostatic potential is applied between a spinneret and a collectorA fluid is slowly pumped through the spinneret.The fluid is usually a solution where the solvent can evaporate during the spinning.The droplet is held by its own surface tension at the spinneret tip, until it gets electrostatically charged.The polymer fluid assumes a conical shape (Taylor cone).When the surface tension of the fluid is overcome, the droplet becomes unstable, and a liquid jet is ejectedBurger, Christian, et. al. Nanofibrous Materials and Their Applications
8 Burger, Christian, et. al. Nanofibrous Materials and Their Applications. 2006.
9 Burger, Christian, et. al. Nanofibrous Materials and Their Applications. 2006.
10 Burger, Christian, et. al. Nanofibrous Materials and Their Applications. 2006.
11 Types of Solvent Stream Ejections Burger, Christian, et. al. Nanofibrous Materials and Their Applications
12 20 wt% Poly(D,L-lactic acid) (PDLA) Nanofibers at voltage of 20 kV, feeding rate of 20 μl min−120 wt%Burger, Christian, et. al. Nanofibrous Materials and Their Applications
13 35 wt% Poly(D,L-lactic acid) (PDLA) Nanofibers at voltage of 20 kV, feeding rate of 20 μl min−135 wt%Burger, Christian, et. al. Nanofibrous Materials and Their Applications
14 Electrospinning Polymers SolventConcentrationPotential ApplicationNylon 6,6Formic Acid10 wt%Protective ClothingPolyurethanesDimethylformamidePolycarbonateDichloromethane15 wt%Sensor, FilterPolylactic Acid14 wt%Drug Delivery SystemThe small size between the fibers allows the capture of particles in the 100- to nanometer rangeThat is the same size of viruses and bacteriaUsed as air-filter: Airplanes, office, etc.Burger, Christian, et. al. Nanofibrous Materials and Their Applications
15 Electrospinning Variables Burger, Christian, et. al. Nanofibrous Materials and Their Applications
16 ApplicationsBurger, Christian, et. al. Nanofibrous Materials and Their Applications
17 Applications Ultrafiltration in water treatment High flux, low-fouling membraneThe top layer provides the actual filtration, and the middle and bottom layer provide sting support and are very porousIncreased efficiencyAble to filter withouttop layer.Burger, Christian, et. al. Nanofibrous Materials and Their ApplicationsBurger, Christian, et. al. Nanofibrous Materials and Their Applications
18 Applications Anti-adhesion in surgery Due to their high surface to volume ratio and being able to conform to different sizes, shapes and textures.Closely match those of native tissueNanofabrics have been used as scaffolds for tissue and cell regeneration of organs.Burger, Christian, et. al. Nanofibrous Materials and Their ApplicationsBurger, Christian, et. al. Nanofibrous Materials and Their Applications
19 Modification, crosslinking, and reactive electrospinning of a thermoplastic medical polyurethane for vascular graft applicationsRecent Research on Electrospinning
20 Thermoplastic polyurethanes Used in medical devices and experimental tissue engineering scaffoldsChemical/mechanical properties hard to balance
21 Methodology Synthesis of a model compound Modification of thermoplastic polyurethanePellethane®Modification ReactionsSample prep and crosslinkingSwelling behaviorTensile testingScanning electron microscopyElectrospun graftsSynthesis of a ModelModificationDegradationElectrospinningJ.P. Theron et al./Acta Biomaterialia
22 Modification of Thermoplastic Polyurethane Modified with reactive phenol groups – NaH was added - different amounts to observe changes with the polyurethaneModified polymer was isolated and purified through precipitations in water and vacuum dryingCrosslinking achieved by UV light or heat sourceSwelling index was determined by gravimetric behaviorTensile testing was performed at room temperature and in a cyclical methodJ.P. Theron et al./Acta Biomaterialia
23 Scanning electron microscopy Surfaces of the samples – degradation studyPellethane and Pell 15.0Control samples (not subject to the degradation media) – used as referencesDetermined the amount of degradation on a scale of 1-5J.P. Theron et al./Acta Biomaterialia
24 Electrospun grafts Small diameter vascular graft prototypes Used an electrospinning apparatus – high voltage power supply, infusion pump, syringe, rotating/translating mandrelTubes removed from mandrelsby swelling in EtOH and driedProduced crosslinked tubular vascular graft prototypeJ.P. Theron et al./Acta Biomaterialia
25 Schematic Representation of the Reactive Electrospinning Apparatus Fibers are irradiated with UV light during spinning in order to form crosslinked graft scaffoldsJ.P. Theron et al./Acta Biomaterialia
26 Experimental ResultsDirect linear correlation between NaH addition and degree of modificationBy adding the NaH, the research group was able to get between 4.5% and 20% modification of the polyurethane.After 20% modification, samples were discolored/started degradingJ.P. Theron et al./Acta Biomaterialia
27 Experimental ResultsThe range of modifications was tested for mechanical strengthThe sample which ranked the best was the Pell15.0, or a 15% modified sample.J.P. Theron et al./Acta Biomaterialia
28 Experimental ResultsThe modified Pell15.0 showed a reduced creep when compared to the Pellethane control – reduction of 44%This is due to the UV crosslinking of Pell15.0.J.P. Theron et al./Acta Biomaterialia
29 ResultsDecrease in swelling index with increased degree of modification –an increased modification led to more densely crosslinked material.Crosslinking also showed a decrease in hysteresis as well as breaking stress and strain.The scanning electron microscope showed that the crosslinked samples had only a few cracks, while the control samples had severe surface degradation with deep cracks.The Pell15.0 was spun with UV light into tubular graft structures 40mm in lengthGrafts diameter (thickness) can be adjusted depending on specific applicationsJ.P. Theron et al./Acta Biomaterialia
30 Crosslinking improved the resistance to degradation. PellethanePell15.0Before AgNO3 DegradingAfter AgNO3 DegradingAfter Hydrogen PeroxideCrosslinking improved the resistance to degradation.J.P. Theron et al./Acta Biomaterialia
31 Conclusions of this Research Exhibit compliance values within physiological rangeCan optimize fibers for mechanical, morphological properties, and in vivo responseTissue regrowth, angiogenesis, inflammatory responseManipulate processing conditionsVascular grafts - repetitive, relatively low stressBio-degradable scaffolds for tissue regenerationCan closely match native tissues - good incorporation in already existing tissueJ.P. Theron et al./Acta Biomaterialia
32 Surface-functionalized Elecrospun Nanofibers for Tissue Engineering and Drug Delivery Recent Research on Electrospinning
33 Electrospun Nanofibers High surface area to volume ratioVersatile method for preparing nanofibrous meshesPotential applications:Biomedical devicesTissue engineering scaffoldsDrug delivery carriersDone through Surface ModificationPlasma treatmentWet chemical methodSurface graft polymerizationCo-electrospinning of surface active agents and polymersCreates bio-modulating microenvironments to contacting cells and tissues"Surface-functionalized Electrospun Nanofibers for Tissue Engineering and Drug Delivery."
34 Surface Modification Techniques Synthetic polymers vs. natural polymersSynthetic: easier processing for electrospinning and more controllable nanofibrous morphologyNatural: difficult to directly process into nanofibers because of unstable nature and weak mechanical propertiesNatural polymers can be immobilized onto the surface of synthetic polymers without compromising bulk propertiesCan incorporate therapeuticalagents directly into the nanofibers"Surface-functionalized Electrospun Nanofibers for Tissue Engineering and Drug Delivery."
35 Modification – Plasma Treatment Changes the surface chemical compositionSelection of plasma source – introduce diverse functional groups on surfacePlasma treatments with oxygen, ammonia, or air – generates carboxyl groups or amine groupsAir or argon treatmentsWhen nanofibers were soaked in a simulated body solution – calcium mineralization occurred on surfaceImproved wettabilityPotential with bone grafts"Surface-functionalized Electrospun Nanofibers for Tissue Engineering and Drug Delivery."
36 Modification – Wet Chemical Method Films and scaffolds under acidic or basic conditions – modify surface wettabilityPlasma treatment can not modify surface of nanofibers deep in the meshWet chemical etching methods can modify thick meshes"Surface-functionalized Electrospun Nanofibers for Tissue Engineering and Drug Delivery."
37 Modification – Surface Graft Polymerization Synthetic biodegradable polymers retain hydrophobic surface – need hydrophilic surface modification for desired responseIntroduce multi-functional groups on the surfaceEnhanced cell adhesion, proliferation, and differentiationInitiated with plasma and UV radiation treatment to generate free radicals for polymerization"Surface-functionalized Electrospun Nanofibers for Tissue Engineering and Drug Delivery."
38 Modification – Co-electrospinning Nanoparticles and functional polymer segments can be directly exposed on surface of nanofibersCo-electrospinning with bulk polymersAny combination of electrospinnable polymer and polymer conjugate can be used"Surface-functionalized Electrospun Nanofibers for Tissue Engineering and Drug Delivery."
39 Target Molecule Loading on Surface Simple physical adsorbtionNanopoarticle assembly on surfaceLayer by layer multilayer assemblyChemical immobilization"Surface-functionalized Electrospun Nanofibers for Tissue Engineering and Drug Delivery."
40 Applications – Drug Delivery Applications – Drug DeliverySuperior adhesiveness to biological surfacesVariety of structures containing drug moleculesDrug release mechanism – polymer degradation and diffusion pathwayCan tailor drug release profiles by varying polymer properties, surface coating, combination of polymersHas been successful in laboratory trials – controlled topical release"Surface-functionalized Electrospun Nanofibers for Tissue Engineering and Drug Delivery."
41 Applications – Tissue Engineering Various cells cultivated on nanofibrous meshesEmbryonic stem cells, mesenchymal stem cellsBetter than other tissue engineering methodsCoronary artery cellsCollagenLimited to in vitro studies because cells could not be loaded within the nanofibrous meshes in large quantities3D nanofibrous scaffolds"Surface-functionalized Electrospun Nanofibers for Tissue Engineering and Drug Delivery."
43 Improvements and Further Research Develop more precise electrospinning techniquesMechanisms of electrospinningGrowth ratesBending InstabilityProducing nanofabrics with specific mechanical properties.Creating 3-dimensional shapesCapable of being used in controlled release of drugs.Burger, Christian, et. al. Nanofibrous Materials and Their Applications
44 Improvements and Further Research Optimization of parametersIntrinsic properties of solutionPolarity, surface tension of solvent,MW of polymer, etc.Controlling nanofiber alignmentElectric fieldModifying type of collectorBetter control of fiber alignment"Electrospin Nanofibers for Neural Tissue Engineering."
45 Improvements and Further Research Reduce Cost of ProductionMake economically viableIncrease production rateIncorporate the use of an array of spinneretsSafetySolventsDangerous to health and environmentPolymersBurger, Christian, et. al. Nanofibrous Materials and Their Applications
46 ReferencesBurger, Christian, Benjamin S. Hsiao, and Benjamin Chu. "Nanofibrous Material and Their Applications." Review. 25 Apr Web. 14 FebHunley, Matthew T., and Timothy E. Long. "Electrospinning Functional Nanoscale Fibers: a Perspective for the Future." Polymer International 57 (2008): Web. 7 MarNASA Tech Briefs Create the Future Design Contest. Web. 08 Mar <http://www.createthefuturecontest.com/pages/view/entriesdetail.html?e ntryID=1857>.Theron, J. P., J. H. Knoetze, R. D. Sanderson, R. Hunter, K. Mequanint, T. Franz, P. Zilla, and D. Bezuidenhout. "Modification, Crosslinking and Reactive Electrospinning of a Thermoplastic Medical Polyurethane for Vascular Graft Applications." Acta Biomaterialia (2010). 27 Jan Web. 05 FebXie, Jingwei, Matthew R. MacEwan, Andrea G. Schwartz, and Younan Xia. "Electrospin Nanofibers for Neural Tissue Engineering." Nanoscale 2 (2010): Print.Yoo, Hyuk S., Taek G. Kim, and Tae G. Park. "Surface-functionalized Electrospun Nanofibers for Tissue Engineering and Drug Delivery." Advanced Drug Delivery Reviews 61 (2009): Print.
48 Rebuttal from U6We agree that we may have used a few too many filler words and will actively try to reduce them in the second presentationOne group thought that we should have been more concise, but we felt like we had the right amount of slides to present the topic thoroughlyOne group would have liked to see a more integrated presentation; we chose to add title slides throughout to let the audience know what we would be discussing next in the presentationPotential further research was discussed in areas which showed promise in the use of nanofibers and the topics which could be researched are endless – one group suggested some additional topics to researchPolyurethane is the material which was used to produce the nanofibers, hence is how it is related to the nanotechnology applicationsWe will keep up the quality of the slides since there were a lot of positive comments about themWe appreciate all the comments and will take them into consideration for our next presentation
49 Review of Electrospinning of Nanofabrics Submitted by U1
50 This presentation particularly caught our attention for its wide range of applications like clothing reinforcement and support for tissue regeneration.Also electrospinning offers the possibility of changing some of the design and material variables to obtain different products makes it very versatile and adaptable for different purposes.Their comparison of different papers that show electrospining base process for the aid of health issues and drug delivery shows that the technology has great future.This presentations was really good overall and meet our expectations. The slides were well constructed and pictures were very helpful in recreating many of the concepts.
51 Electrospinning of Nanofabric Review of Group U6’s Presentation-Electrospinning ofNanofabricBy Group U2:-Kyle Demel-Keaton Hamm-Bryan Holekamp-Rachael Houk
52 The presenters did really well at: Speaking – all presenters in this group were easy to hear and understandOutlining the presentation and going in a logical and easy-to-follow orderGiving a thorough introductionMaintaining consistency in text size/fontsUsing big and helpful graphicsDiscussing the articles in detailOther future applications to discuss:Clothing that repels germs, dirt, allergensClothing with microelectronic nano-generators to produce energyIncorporating microelectronics with three-dimensional tissue engineeringVideo-imaging on skinAdding nanofabrics to buildings
53 Electrospinning of Nanofabrics Group 3:Krista Melish James KancewickPhillip Keller Mike Jones
54 Presentation Review: Ugrad #6 Material ReviewEffective job communicating the materialI have never heard of electrospinning before, and I was able to follow along and understand what was being presented easilyNeed to reduce use of verbal distractors (umm, like, etc.) and pausesAlways a need to reduce these, but overall the material was communicated clearlySome pictures seemed unnecessaryPictures are nice to have but just including them to fill space (such as on the second further improvements slide) should be limitedInstead, condense several points onto a single pageOverall Grade: 95The introduction was concise, yet effective in explaining basic concepts that the research paper looked at further.The graphics used to depict size, demonstrate procedure, and present results were utilized very effectively within the presentation.For example, the process of electrospinning was shown very clearly in your report through the use of several figures. Effective visual format for the material.Questions for further research:Very specific, showing deep thought and breadth of knowledgeGood detail in specifying which aspects of electrospinning should receive further attentionGood insight considering the safety of the materials used and generated, this subject is generally neglected.
55 Electrospinning of Nanofabrics Review by Group U4Burger, Christian, et. al. Nanofibrous Materials and Their Applications
56 Review of Oral presentation and Slides Both presenters were audible from the back of the roomConfidence was lacking in the second presenter, sentences were repeated multiple timesPresenters, when not presenting should still look engaged not bored staring into spaceSlidesIt seemed like information could have been more concise, but it was split up to make the presentation look longer.Pictures on pages were not always related to the information discussed.Everything was well citedGraphs and tables were easy to read and understand
57 Technical ContentAll aspects of electrospinning were described in detail.Research against the subject seemed lacking, and what was done didn’t seem to have a rebutal.Further research was very in depth, present a second paper on the medial uses of electrospinningVery informative, but further research is needed to determine, among others, if it will affect the consumer in a negative way.Burger, Christian, et. al. Nanofibrous Materials and Their Applications
58 Review of Electrospinning of Nanofabrics Review of Group U6 by Group U558
59 Oral and Quality of Slides Speakers had very good oral presentation skills. Clear, confident, and knowledgeable in their discussion.Font size and pictures were appropriately sized and well cited.
60 Technical ReviewVery sound technical report. Appeared to have extensive and relevant research.Would have liked to see a more integrated presentation, instead of segmented by paper titles.
62 I didn’t clearly understand how the thermoplastic polyeurethane is related to the nanotechnology. Is this material a type of “nanofibers” described earlier in the presentation? The connection between these will help improve the presentation.How is the homogeneity achieved during the co-electrospinning? Is this something that must be controlled? Does it have an impact on the final product?