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Encapsulation of Single-Walled Carbon Nanotubes in Microgels. Amelia Lin Texas Academy of Mathematics and Science Mentor: Dr. Zhibing Hu UNT Department of Physics. Microgels Image provided by Georgia Tech Image. Carbon nanotubes.
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Encapsulation of Single-Walled Carbon Nanotubes in Microgels Amelia LinTexas Academy of Mathematics and Science Mentor: Dr. Zhibing Hu UNT Department of Physics MicrogelsImage provided by Georgia Tech Image
Carbon nanotubes • Essentially a sheet of graphite rolled up into a tube and capped at the ends with fullerene halves • Extensive range of unique physical and chemical properties • Applications span across fields including physics, chemistry, and materials science Image provided by Saito Laboratory, Nagoya University
Problems with biological applications • Carbon nanotubes are cytotoxic, or toxic to cells, curtailing developments in biomedicine and biotechnology • Biosensors • Drug delivery agents • Selective cancer cell destruction
Smart hydrogels • Hydrogels: macromolecular networks that can retain a high percentage of water within their structure • Smart hydrogels: hydrogels that respond to environmental stimuli • Biocompatible
Microgels • Form of hydrogels • Roughly-spherical particles • Polymer strands • Crosslinking agent
Objective – encapsulation of CNTs in microgels • Encapsulate CNTs in a biocompatible material • Applications in biomedicine and biotechnology • Biosensors • Drug delivery agents • Selective cancer cell destruction
Methodology Part 1: Functionalize carbon nanotubes (CNTs) to have the same end structure as the crosslinking agent Part 2: Substitute functionalized CNTs for the crosslinking agent
Methodology – Part 1 BIS (crosslinking agent) Part 1: Match end structure • PNIPAAm* microgels • Thermo-responsive, smart hydrogel • BIS* crosslinking agent * Poly(N-isopropylacrylamide (PNIPAAm) N-isopropylacrylamide (NIPA) N, N’-Methylene-bis-acrylamide (BIS)
Methodology – Part 1 Treat with nitric and sulfuric acid Part 1: Match end structure React with NMH* and EDC* *N-(3-Aminopropyl)methacrylamide hydrochloride (NMH) N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC)
Methodology – Part 2 Part 2: Synthesize microgels using functionalized CNTs Functionalized CNTs + Conventional microgel synthesis at 70°C CNTs encapsulated in microgel NIPA* monomer *N-isopropylacrylamide (NIPA)
Result 1: CNTs encapsulated in microgels Compare with: Image provided by Georgia Tech Image
Result 2: Average radius of resultant microgels decreases with increasing temperature
Result 3: Addition of crosslinking agent yields different properties CNTs + BIS CNTs + BIS CNTs only CNTs only
Conclusions • Successful encapsulation • Introduction of CNTs into the human body • Applications in biomedicine and biotechnology • Biosensors • Drug delivery agents • Selective cancer cell destruction • Integration with a material that already has applications • Novel method for substituting crosslinking agent in microgels
Future Directions • Elucidation of physical and chemical properties of resultant microgels • Transmission electron microscopy • Scanning electron microscopy • Infrared and nuclear magnetic resonance spectroscopy • Investigation of unexpected results - Possible encapsulation of individual nanotubes • Encapsulation of other nanoscale materials Application of method to other materials • Quantum dots
Acknowledgements • Prof. Zhibing Hu, for his time and guidance • Dr. Tong Cai, for his invaluable help and inexhaustible patience • Dr. Richard Sinclair and Dr. John Ed Allen, for their sponsorship of my work • Dr. Ray Baughman, for first opening his lab door to me in 2004 and for the inspiration and support since then • CollegeBoard and the Siemens Foundation, for hosting and making this event possible