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Interfaces and Surfaces NSF REU SiteDepartment of Materials Science and Engineering, Clemson UniversityMay-August 2013Transferability Experiment:1. Pipette out seeded fibers from well with cut-tip pipette. Avoid scraping the bottom of well.2. Remove pump from syringe’s body. Pipette the fibers media into syringe. Reinsert the pump.3. With the needle attached, transfer fibers from syringe to a clean well.4. Incubate for 2-3 hours and check for cells viability.Results and Discussion:Initial results clarify the success of the first stage of research: cutting fibers into small lengths and get fibroblaststo grow on them. The result also indicates that cells can grow and attach to micro fibers no matter whatorientations the fibers are in due to the novel design of the cross-section. The high level of cells interaction andfibers aggregation seen in fig. 2, 7 days after seeding show that cells can strongly proliferate and that they canreach out to surrounding to establish connection.The results for the transferability experiment show that after passing through a range of needle gauges, cells arestill attached to fibers and survive. The grooves on the cross section most likely play a significant role in keepingthe cells on the fibers during transfer. Seeded fibers can be transferred through a 25G needle, which is close to the27G target, a common gauge for brain injection. However, almost none of the fibers could get through the 30Gneedle.PVAspectrum Fig.1:Theredcurveisthefiberif exists. eseen.Conclusions: The method of cutting and fiber processing proves to be successful as cells were able to attach tothe fibers, and no residue from the cutting embedding medium was left. This study shows that PLA CCP fiberseffectively act as micro-carriers that support cell growth and control cell morphology and alignment. 3T3fibroblasts attachment and proliferation on injectable sized fibers shows potential in further research intoneurodegenerative disease treatment. Not only that, the seeded fibers can also be transferred using needle whilemaintaining cell’s viability and attachment, an important step toward clinical application in the future.Future work: Seeding cells onto smaller length fibers (100-150 microns). Dispersing seeded fibers into hydrogel composition to see if fibroblasts will extend out into hydrogel.Ultimately, the goal would be to inject a hydrogel composition of seeded fibers and cell growth biaseddrugs into target area of the brain. Seed neurons onto PLA CCP fibers and then onto different polymer fibers with shorter biodegradabletime. Seed neuron stem cells (NSCs) onto CCP fibers. Further research on differentiation of NSCs to neurons.

Interfaces and Surfaces NSF REU SiteDepartment of Materials Science and Engineering, Clemson UniversityMay-August 2013Acknowledgements: I would like to thank Graduate Students: Atanu Sen, Lee Ho Joon, Histology Lab Manager,Chad McMahan, Cell and Tissue Culture Lab Manager, Cassie Gregory, and MSE Analytical Lab Manager,Kimberly Ivey. This work was supported by the National Science Foundation’s REU program under grant number1062873, CU COMSET, the School of Material Science and Engineering, and the School of Bioengineering.

Interfaces and Surfaces NSF REU SiteDepartment of Materials Science and Engineering, Clemson UniversityMay-August 2013Hardness Evolution of Metallic Surfaces due to Wear TestingR. Askew1, C. Eljach2, J. DesJardins2College of Engineering, Tuskegee University, 360882Department of Bioengineering, Clemson University, 296341Introduction: TKRs are a successful orthopedic surgery; however, there are a high number of revisionsthat occur every year. Previous work has shown that the most common limiting factor in theperformance of TKR joints has been the wear of ultra-high molecular weight polyethylene (UHMWPE)used as a bearing component [1]. Cobalt chrome (CoCr) is one of the most commonly used metal in thefemoral component in knee replacements. Polyethylene is a plastic spacer placed between the femoraland tibial components. Titanium metal is used in the tibial component in TKRs. Wear is described as:the process of material loss due to some friction. In this study, we focus on the Cobalt chrome instead,primarily because in previous studies the focus has been of the non-articulated cobalt chrome. Our studyis to determine whether or not the wear process affected the pin’s hardness.Materials and Methods: Six Cobalt Chrome metal alloys (distributed by DJO surgical) were selectedfor this study for wear testing in the orthopod. A UMT Multi-Specimen Test System in a pin-on-discmode was used to create twelve different loads on Cobalt Chrome pins ranging from 1N to 12N. Afterthe pin-on-disc method, CoCr pins are weighed and examined through Vickers Microhardness Tester(Huayin HV-1000B). Pins undergo wear testing in orthopod which utilizes bovine serum (composed of75% deionized water) as lubrication to serve as synovial fluid found in a human knee. Polyethyleneserves as a spacer during wear testing. Orthopod loads CoCr pins onto polyethylene surface and begins acircular motion. After wear testing, CoCr are measured for hardness (HV) which determines the strengthand compatibility of Cobalt Chrome prior to five year implantation (80km).Results and Discussion: At 0km each point (left, right and inside of the scratch) was found to be greaterthan the “clean area” by 50. Change in material hardness (an average of 44.22 HV for each point offocus) is discovered following wear testing of up to 80km. The hardness gap was decreased due to weartesting. Logically, change in hardness was expected as a result of activity (walking, minimal exercise,etc.). Once CoCr pins reach 80km the difference in hardness was reduced to an average of 15.8. In Table1, the considered “Clean Area” decreased in hardness by 21.7HV, Left Side of Scratch by 55.3HV,Inside of the scratch by 53HV and the Right Side of Scratch by 46.8HV. We hypothesized that therewould be a change in hardness due to wear testing; results have shown us just that. In conclusion, overfive years implantation hardness values decreased by an average of less than 16%. Using a t-test inexcel, each area were tested from before wear at 0km to following wear at 80km. In conclusion each pvalue had a value of 0.5; therefore, hardness evolution was statistically significant as shown in Table 1:

Interfaces and Surfaces NSF REU SiteDepartment of Materials Science and Engineering, Clemson UniversityMay-August 2013Hardness Vickers (HV)Hardness Evolution: 0KM versus80KM3503002502001501005000KM "clean"80KM "clean"0KM inside80KM insideTable 1: This tablerepresents the hardnessaverages from 0KM to80KM from each point offocus.0KM left80KM left0KM rightConclusion: Excessive loading during hardness testing can cause inaccurate measurements resulting inindenting through the material resulting in catastrophic damage. Adjust study to replicate aggressive invivo damage and focus on properties of active patient and apply. Possibly quantify wear and hardness ina single project to determine a correlation.Acknowledgements:I would like to thank Dr. DesJardins and Caleb Eljach for their assistance,patience and guidance with my project. Also, I would like to thank Dr. Kennedy for the opportunity andher Ph.D. student, Brad Schultz. This work was supported by the National Science Foundation’s REUprogram under grant number 1062873, CU COMSET and the School of Materials Science andEngineering.References:[1] Vaidya C, et al. Reduction of total knee. 2011. 225(H1):1-7.

Interfaces and Surfaces NSF REU SiteDepartment of Materials Science and Engineering, Clemson UniversityMay-August 2013Dynamic Simulations of Self-healing Polymer1R.K. Bay1, Y. Yang2, M.W. Urban2Department of Material Science and Engineering, Rensselaer Polytechnic Institute, 121802Department of Materials Science and Engineering, Clemson University, 29634Introduction: When damage occurs to a polymer, the chains undergo cleavage and slippage. For thepolymer to self-heal, bond reformation and network repairs must occur under favorable thermodynamicconditions. In this study, computer simulations are utilized for the first time to understand physicalresponses of self-healing. When a polymer is scratched the glass transition temperature is decreased atthe interface of the scratch and the interface is above glass transition temperature. When a polymer isabove the glass transition temperature it is in a rubber state compared to its glass state. The interface thatis above glass transition temperature flows to fill the scratch. From past studies, as the scratch heals asymmetrical ridge is observed at the bottom of the scratch and a scar forms on the surface of thepolymer. The scar on the surface is from the free volume of the polymer [1][2][3].Materials and Methods: In this study Comsol Multiphysics software was used to create a simulation ofthe self-healing of a polymer. In this simulation it was assumed that the flow was incompressiblebecause the polymer was flowing in its solid rubbery state. Thermoset polyurethane was used as thesimulation polymer at a density of 1.17 g/cm3. Atmospheric pressure on the open interface of thegeometry was assumed and a healing volume force was applied to the geometry. The healing volumeforce can be from the activation energy to have the polymer chains move. The geometry of the scratchwas 60 meters deep, 20 meters wide, and 10 m thickness between the surfaces of the scratch in whichthe polymer was allowed to flow. Meters were used instead of microns because of the computation timeto run the simulation required was much higher in microns than to run the simulation in meters. Thehealing volume force was increased to 10 N/m3 with the understanding that the actual force from thechemical bonds breaking from the scratch ranges from 10-6 to 10-10 N/m3 in the micrometers geometry.Laminar flow and turbulent flow simulation were compared to identify the type of flow that forms thesymmetrical ridge. The laminar flow model used the Non-Newtonian Carreau Model with an infinitedynamic viscosity of 15Pa*s. The k-ε turbulence model was used to model the turbulent flow. Theviscosity of the scratch surfaces has not been measured before therefore the dynamic viscosities of 10Pa*s and 15 Pa*s to identify if healing dynamics changed with a change in viscosity. Round and sharpscratch bottom surface were compared to identify which one was able to form the symmetrical ridge.Results and Discussion: In the turbulent flow models, the growing of a symmetrical ridge is observedin the bottom of the scratch due to a pressure buildup below the scratch (Figure 1). The polymer flowsinitially from the top of the geometry in a laminar state in both the turbulent models and the laminarmodel. The increasing the viscosity in the turbulent model from 10 Pa*s to 15 Pa*s increases the heightof the symmetrical ridge by one meter. In the non-Newtonian laminar flow the surface closes together tocreate a new round surface and an increase in pressure is observed below the scratch and no symmetricalridge is observed. For the sharp geometry, the surface closes together and creates new sharp bottomsurface in the turbulent model, and pressure build up is observed below the surface although nosymmetrical ridge is observed. The simulation was able to run until the boundaries of the inside ofscratch collided. When the boundaries collided the software was not able to recognize the boundaries didnot exist anymore and therefore the growth of the ridge was stopped. When the boundaries collide in the

Interfaces and Surfaces NSF REU SiteDepartment of Materials Science and Engineering, Clemson UniversityMay-August 2013simulation it represents bond reformation and network repair. If the simulation was run after the pointthe boundaries collided the material would start to overlap and a loss of material would occur.Figure 1. Pressure plot of the turbulent model with a dynamic viscosity of 10 Pa*s and roundbottom geometry. A symmetrical ridge is observed with a pressure point at (0, 3.3) around234.1kPa.Conclusions: During healing a symmetrical ridge in the bottom of scratch is formed by a pressurebuildup. The symmetrical ridge grows up until the polymer is fully healed. The symmetrical ridge isformed due to turbulent flow, indicated by the simulation. The bottom of the scratch has to be round forthis symmetrical ridge to occur.Acknowledgements: This work was supported by the National Science Foundation’s REU programunder grant number 1062873 and the Center for Optical Materials Science and EngineeringTechnologies (COMSET).References:[1] B. Ghosh, M. W.Urban, Science. 2009, 323, 1458-1460.[2] B.Ghosh, K.V. Chellappan, M.W.Urban, B. Ghosh , J. Mater. Chem., 2011, 21,14473-14486.[3] B. Ghosh , K. V. Chellappan and M. W. Urban, J. Mater. Chem., 2012, 22, 16104-16113.

Interfaces and Surfaces NSF REU SiteDepartment of Materials Science and Engineering, Clemson UniversityMay-August 2013Reconfigurable Diffraction Gratings with Magnetic NanorodsJ.Custer1, Y. Gu1, K. Kornev11Department of Materials Science and Engineering, Clemson UniversityIntroduction:The purpose of this study was to develop a reconfigurable diffraction grating by using magneticnanorods. Such a diffraction grating would be of use in advancing the field of spectrometry. Diffractionis a phenomenon that causes light to spread out after being transmitted through a small opening. Adiffraction grating creates such openings in the form of regularly spaced gaps. The distance between thegaps and the wavelength of light determine the resulting diffraction pattern. Most diffraction gratingshave a set gap size and thus cannot be reconfigured. This study sought to use a magnet to align nickelnanorods in a fluid and to use the gaps between the nanorods as a diffraction grating. Becauserepositioning the nanorods with a magnet could control the gap size, the grating would be reconfigurablewhich would allow for more versatile spectrometers. This would be beneficial to applications ofspectrometers including material identification and use in endoscopes.Materials and Methods:The synthesis of the nickel nanorods followed the traditional electrolysis procedure.1-An inorganic filtermembrane with 0.2 mm pore size was coated with gallium-Indium. The coated membrane was placedupon a copper plate (coating side down) and a graduated cylinder that was open on both ends wasclamped over it. A WATTS solution (300g/L NiSO4*H2O, 45g/L H3BO3, 45g/L NiCl2*6H2O) waspoured into the graduated cylinder and a nickel wire was placed in the solution. A negative lead wasattached to the copper plate, and a positive lead was attached to the nickel wire. Electricity was appliedfor 12 minutes at 1.5 V. Nitric acid was then used to remove the gallium-Indium coating on themembrane. The membrane was dissolved in a solution that consisted of 4% NaOH, 2% PVP(Polyvinylpyrrolidone) and 94% H2O (percentage is by weight). The PVP coated the nickel nanorodsand prevented aggregation.2 After dissolving in the NaOH solution for at least 24 hours; the nanorodswere sonicated and then transferred to a glycerin solution using a centrifuge. This resulting solution wasviewed under a dark field microscope at 50X magnification and contained distinct nanorods devoid ofaggregation. In the presence of a magnetic field, the nanorods would rotate in order to orientatethemselves parallel to the field. When a field gradient was present, the magnetic force would drag thenanorods towards the higher field position. As the nanorods reached the edge of the drop, they wouldform chains while remaining parallel to the magnetic field and maintaining separation from the otherchains (See figure 1 on next page). A red laser (wavelength of 635 nm) was directed through a sample ofthe solution containing the nickel nanorods. When a magnet was placed underneath the sample (thuscausing the magnetic field to be perpendicular to the laser), a diffraction pattern appeared upon a screenplaced 0.5 m behind the sample. This diffraction was in the form of a solid line that could be rotated bymoving the magnet to the right or left of the sample.Results and Discussion:Adding PVP to the NaOH solution caused the PVP to coat the nanorods, which helped the nanorods toavoid aggregation. The nanorods were also more stable in glycerin than in water. This was clearly seenby comparing images of nanorods in each of the two solutions. The nanorods in water formed large

Interfaces and Surfaces NSF REU SiteDepartment of Materials Science and Engineering, Clemson UniversityMay-August 2013bundles while the nanorods in glycerin remained separate for the most part and would only attach toeach other at the ends of the nanorods. When a magnetic field was applied, the nanorods essentiallybecame induced bar magnets that could line up head to tail, but would show repulsion between the shaftsof the nanorods. This explains why the nanorods would form chains (head to toe bonding) that wouldstay separate from other chains (shaft repulsion). See Figure 1 on the next page. The diffractionobserved was caused by the gaps between these chains. However, because of the inhomogeneity in thegap distances, the peaks of the diffraction pattern could not be reliably distinguished.Figure 1. PVP coated nanorods in glycerol in presence of a magnet, dark field imageConclusions:Nickel nanorods appear to be a viable method to creating a reconfigurable diffraction grating. This studyhas shown that it is possible to create nanorods that can be manipulated magnetically and that will notconglomerate into large bundles. Also, these nanorods have been observed to cause diffraction, althoughthe diffraction achieved was not distinct enough to allow for much analysis. However, the use of a clearmicrochannel is hoped to be implanted in the future. The width of the microchannel will beapproximately the height of the nanorods. This should stop the nanorods from forming chains and allowonly the shafts of the nanorods to interact with each other. This would permit more precise control of thespacing between the nanorods as well as a more consistent gap size. Having a more consistent gap sizewill cause the diffraction pattern to appear more distinctly allowing for uses in spectrometry.Acknowledgements:This work was supported by the National Science Foundation’s REU program under grantnumber 1062873 and the Center for Optical Materials Science and Engineering Technologies(COMSET).References:1Bentley, A. K.; Farhoud, M.; Ellis, A. B; Lisensky, G. C; Nickel, A. L.; Crone, W. C. TemplateSynthesis and Magnetic Manipulation of Nicke

Sterilization process has to be done in laminar hood except when centrifuging 1. Fill tube with 70% Ethanol until all fibers are submerged. Let it sit for 30 minutes. 2. After 30 minutes, wash fibers with sterile water 4 times. Remove supernatant. Fibers Preparation for Cell Seeding: 1. Prepare dilution of 20µg/mL fibronectin.