Nanocomposites of Cellulose For Medical Application Asif Rasheed Lecturer, Department of Chemistry University of Wisconsin, Whitewater 800 West Main Street, Whitewater, WI 53190 rasheeda@uww.edu

Cellulose: The most abundant, biodegradable and biocompatible polymer Applications include fiber, paper, membrane, polymer and paint industries Tissue engineering Nanocomposites Strong intra and intermolecular hydrogen bonding hence difficult for processing H - bonding is reduced by partial replacement of hydroxyl groups, this process involves complex multiple steps and uses toxic chemicals => Conern to Environment Effect on Nano-filler

Cellulose Dissolution Ionic Liquid: Able to break down H-bonding in biopolymers, hence can dissolve biopolymers e.g. cellulose and silk 1-ethyl-3-methylimidazolium acetate (EMI acetate) Cellulose pulp paper (Grade V-60) from Buckeye Technologies Inc. Degree of Polymerization ~ 820 Control cellulose film regenerated from ionic liquid

Composites of cellulose and vapor grown carbon nanofiber (VGCNF) and carbon nanotubes Composites of cellulose and hydroxyapatite (HAP)

1) Cellulose-CNT Nanocomposite SWNT MWNT VGCNF Young’s Modulus ~ 1 TPa Electrical Conductivity ~ 100 times Stronger than Steel at 1/6th of weight Thermal Conductivity

Previous Experience with Polyacrylonitrile (PAN)/VGCNF Nanocomposites Mechanical Properties Electrical Conductivity Thermal Stability Experimental and theoretical specific modulus of various PAN/VGCNF composite films assuming the modulus of VGCNF to be 50 GPa. (a) Experimental modulus, (b) theoretical modulus assuming VGCNF length to be 0.2 m, (c) 1 m, (d) 10 m and (e) 100 m. Electrical conductivity of PAN/VGCNF composite films. Tan δ (below) as a function of temperature for (a) Control PAN, (b) PAN/5%VGCNF, (c) PAN/10%VGNCF, (d) PAN/20%VGCNF, (e) PAN/40%VGCNF and (f) PAN/90%VGCNF composite films. Guo, H.; Rasheed, A.; Kumar, Satish J Mater Sci (2008) 43:4363-4369

Enhance tensile strength and tensile modulus Impart thermal stability Incorporation of a nano-filler (SWNT, MWNT, VGCNF) into cellulose matrix is expected to Enhance tensile strength and tensile modulus Impart thermal stability Reduce shrinkage (dimensional stability) Result in electrical conductivity in the nanocomposite Electroactive paper Actuators/sensors Medical Devices Cellulose+5%VGCNF

2) Cellulose/Hydroxyapatite Nanocomposites Hydroxyapatite (HAP) Ca10(PO4)6(OH)2 finds many applications as bio-material Filler to replace amputated bone Coated to promote bone in-growth into prosthetic implants Cellulose Hydroxyapatite composites have great potential to be used in bone tissue engineering

Previous Reports: Cellulose/HAP Composites Precipitated on cellulose in-situ from aqueous solution* Deposition of HAP limited to surface The process is extensively long (up to ~14 days) to prepare the composite Current Approach Homogenous dispersion of HAP in cellulose matrix Fast processing Composition of composite can be easily varied Cellulose+10% HAP Cellulose+60% HAP *Materials Letters 60 (2006) 1710-1713 Hong, L.; Wang Y. L.; Jia, S. R.; Huang, C. G.; Wan, Y. Z. 2005. Hydroxyapatite/bacterial Cellulose Composites Synthesized via Biomimetic Route. Materials Letter. 60:1710-1713

Acknowledgments Students (Peter Zastraw, Matthew Magruder, Travis Martin) Prof. Peter Jacobs (Geology Department, UW-Whitewater) for XRD UW-Whitewater for funding Department of Chemistry, UW-Whitewater

Cellulose/HAP Composites: XRD Testing for biocompatibility