THE FUNCTIONALIZATION AND CHARACTERIZATION OF ADHERENT CARBON NANOTUBES WITH SILVER NANOPARTICLES FOR BIOLOGICAL APPLICATIONS A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Engineering By ADAM ANTHONY MALESZEWSKI B.S., Wright State University, 2007 2011 Wright State University WRIGHT STATE UNIVERSITY SCHOOL OF GRADUATE STUDIES May 9, 2011 I HEREBY RECOMMEND THAT THE THESIS PREPARED UNDER MY SUPERVISION BY Adam Anthony Maleszewski ENTITLED The Functionalization and Characterization of Adherent Carbon Nanotubes with Silver Nanoparticles for Biological Applications BE ACCEPTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF Master of Science in Engineering. Sharmila M. Mukhopadhyay, Ph.D. Thesis Director George Huang, Ph.D., PE, Chair, Mechanical and Materials Engineering College of Engineering and Computer Science Committee on Final Examination Sharmila M. Mukhopadhyay, Ph.D. Saber Hussain, Ph.D. Allen Jackson, Ph.D. Andrew Hsu, Ph.D. Dean, School of Graduate Studies Abstract Maleszewski, Adam Anthony. M.S.Egr., Department of Mechanical and Materials Engineering, Wright State University, 2011. The Functionalization and Characterization of Adherent Carbon Nanotubes with Silver Nanoparticles for Biological Applications. The purpose of this project is to form silver nanoparticles (Ag-NP) attached to a hierarchical substrate for possible use in biological applications. The effectiveness of these Ag-NP-containing devices, including biofilters and biosensors, may be dramatically enhanced by the use of hierarchical structures such as carbon nanotubes (CNT), as they offer a high surface area surface suitable for cell-device interactions, while Ag-NP would be a suitable component in many such devices due to its plasmonic surface properties (e.g. in sensor and directed energy applications) and its anti-microbial properties (desirable for fluid filtration due to its low weight. Meaningful control over the Ag-NP sizes and degree of adherence has been achieved. The interaction between silver and human epidermal cells as would be present in Ag-NP-based wound dressings has also been investigated in vitro and is discussed. iii Table of Contents CHAPTER 1. INTRODUCTION .......................................................................................... 1 CHAPTER 2. RESEARCH OBJECTIVES ........................................................................... 5 CHAPTER 3. LITERATURE REVIEW ............................................................................... 6 3.1 METAL NANOPARTICLE SYNTHESIS METHODS ...................................................................... 6 3.1.1 Electroless Deposition ........................................................................................ 7 3.1.2 Photodeposition ............................................................................................... 10 3.1.3 Gas-Catalyzed Solid-State Reduction ............................................................... 11 3.1.4 Laser Ablation .................................................................................................. 11 3.2 SUBSTRATE TOXICITY ..................................................................................................... 13 3.2.1 Carbon Nanotubes ........................................................................................... 13 3.2.2 Silver Nanoparticles ......................................................................................... 14 CHAPTER 4. SYNTHESIS PROCEDURE ........................................................................ 19 CHAPTER 5. SAMPLE COMPOSITION AND QUANTITY.......................................... 24 5.1 X-RAY PHOTOELECTRON SPECTROSCOPY .......................................................................... 24 5.1.1 X-Ray Photoelectron Spectroscopy Procedure ................................................ 24 5.1.2a X-Ray Photoelectron Spectroscopy Discussion .............................................. 25 5.1.2b X-Ray Photoelectron Spectroscopy Individual Scans..................................... 27 5.2 ENERGY DISPERSIVE X-RAY SPECTROSCOPY....................................................................... 42 5.3 SCANNING ELECTRON MICROSCOPY ................................................................................ 44 iv 5.3.1 Scanning Electron Microscope Measurement Procedure ................................ 47 5.3.2 Scanning Electron Microscopy Results ............................................................ 53 CHAPTER 6. SONICATION-BASED ANALYSIS ........................................................... 57 6.1 SONICATION-BASED ANALYSIS PROCEDURE ...................................................................... 57 6.2 SONICATION-BASED ANALYSIS RESULTS/DISCUSSION ......................................................... 58 CHAPTER 7. BIOCOMPATIBILITY ASSESSMENT ..................................................... 66 7.1 FLUORESCENCE-BASED BIOCOMPATIBILITY ANALYSIS PROCEDURE ......................................... 66 7.2 BIOCOMPATIBILITY RESULTS/DISCUSSION ......................................................................... 70 CHAPTER 8. SUMMARY AND CONCLUSIONS ............................................................ 76 CHAPTER 9. FUTURE RECOMMENDATIONS ............................................................ 78 9.1 BIOSENSOR ................................................................................................................. 78 9.2 BIOFILTER ................................................................................................................... 79 9.3 WOUND DRESSING ...................................................................................................... 80 APPENDIX 81 A. WETTING ANGLE ANALYSIS ............................................................................................. 81 B. SAMPLE OF BACKGROUND CHOICES OF XPS SPECTRA ........................................................... 85 C. 80° REDUCED SAMPLE 10,000X MAGNIFIED MICROGRAPH .................................................. 88 D. CHEMICALS/EQUIPMENT ................................................................................................ 88 REFERENCES 92 v List of Figures Figure 4.1: A schematic displaying the substrate to finished hybrid structure. ............... 20 Figure 4.2: A schematic of the apparatus mid-reduction. For simplicity, the thermocouple and stir bar are not pictured. The stir bar would appear in the sheath which supports the sample shelf, while the thermocouple would appear adjacent to the top face of the sample. .................................................................................................................... 23 Figure 5.1: A AgNO3 control sample general scan XPS spectrograph showing a small C 1s peak due to a layer of silver nitrate on the sample surface (A 60 °C reduction temperature sample shown). ............................................................................................. 28 Figure 5.2: A reduced sample general scan XPS spectrograph showing a large C 1s peak due metallic nanoparticles beading on the surface revealing CNTs (sample 1 shown). ... 29 Figure 5.3: A composite spectrograph depicting XPS spectra collected in different locations of the AgNO3 control sample in the C 1s regime. ............................................. 30 Figure 5.4: A composite spectrograph collected from three reduced samples depicting XPS spectra in the C 1s regime......................................................................................... 31 Figure 5.5a: A spectrograph of a reduced sample fit with three curves lying at 284.5, 285.8, and 290.3 eV. ......................................................................................................... 32 Figure 5.5b: A composite spectrograph comparing the C 1s peaks of three reduced samples with bare HOPG, indicating the formation of a carbon bonding structure during the reduction process. The HOPG peaks lie on the bottom at the position indicated. ..... 33 Figure 5.6: A composite spectrograph depicting three XPS spectra collected in different locations of the AgNO3 control sample in the Ag 3d regime. .......................................... 34 vi Figure 5.7: A composite spectrograph collected from three reduced samples depicting XPS spectra in the Ag 3d regime. ..................................................................................... 35 Figure 5.8: A composite spectrograph depicting three XPS spectra collected in different locations of the AgNO3 control sample in the N 1s regime. ............................................. 36 Figure 5.9: A composite spectrograph collected from three reduced samples depicting XPS spectra in the N 1s regime. ....................................................................................... 37 Figure 5.10: A composite spectrograph depicting three XPS spectra collected in different locations of the AgNO3 control sample in the O 1s regime. ............................................. 38 Figure 5.11: A composite spectrograph collected from three reduced samples depicting XPS spectra in the O 1s regime. ....................................................................................... 39 Figure 5.12: A composite spectrograph depicting three XPS spectra collected in different locations of the AgNO3 control sample in the S 2p regime. ............................................. 40 Figure 5.13: A composite spectrograph collected from three reduced samples depicting