1. May 17, 2007 Final Project Presentation P E M PemPlant Co. Maricela Delgadillo Kay Furman Yushan Kim

2. PemPlant Co. 2 Industrial Application: Medical Devices Pacemakers and Defibrillators ▪Correct abnormal heart rhythm ▪Size: 1.7x1.9x.3 in; 2.4x2x0.6 in Potential for Bacteria Exposure ▪6% of all vascular surgeries result in surgery site infection (HPA) ▪Skin contact, handling, open wound ▪1-2 hr surgical procedure ▪Current standard of care: antibiotics Our Solution: ▪Antibacterial poly-electrolyte multilayer coatings on titanium Images from http://www.medtronic.com/

3. Polyelectrolyte Multilayers (PEMs) Systems Analyzed ▪3.0/3.0 polyacrylic acid/polyacrylamide (PAA/PAAm) ◦ 5.5 Bilayers ◦ Crosslink 130 º C for 2 hrs ▪2.0/2.0 polyacrylic acid/polyallylamine hydrochloride (PAA/PAH) ◦ 9.5 Bilayers ◦ Crosslink 80 º C for 30 min PemPlant Co. 3 Michael C. Berg March 2005 PAAPAAmPAH

4. PemPlant Co. Validation: Methylene Blue bare Ti 3.0/3.0 PAAm/PAA Solution of 1 M pH 7.0 Binds carboxylates Indicates adhesion of polymer on Ti substrates 2.0/2.0 PAH/PAA

5. PemPlant Co. 5 Modulus by AFM Si 3 N 4 nitride probe on cantilever to measure F vs s upon approach E obtained by linear regression of Hertzian contact model Ti substrate: E = 123 KPa Glass: E = 500 Kpa 1 Surface roughness challenges PAA/PAH 2.0/2.0 on Ti 1 Thompson et al., Biomaterials 26 (2005) 6836–6845

6. PemPlant Co. 6 Bacteria Experiment: Methods Samples in Staph. epidermidis bacteria solution [10 6 cells/mL] 2 h, 4 h, or 8 h 37°C incubation for cell adhesion Remove sample, lay agar gel on top Approx. 24 h incubation for growth of attached cells Visible colonies: 1 per adhered cell TiGlass Whole-slide photography Microscopy

7. PemPlant Co. Whole-slide image analysis (WCIF ImageJ) Bacteria Experiment: Methods

8. PemPlant Co. Bacteria Results * Ti performs well as a PEM substrate Effects withstand time-course test of 4 hours Decreased bacteria viability over time: 8 hour adhesion incubation yielded no viable bacteria

9. PemPlant Co. Bacterial Adhesion Bare substrate2.0/2.03.0/3.0 Glass Ti Surface features ▪Bacteria settle in imperfections on bare Ti ▪PEMs even prevent colony formation on features 40 μm 5 mm

10. PemPlant Co. 10 Wear Testing Apparatus/Procedure Finger Pressure ~ 50g-100 g Probe mass: 61.3 g ▪50 g weight ▪Rubber ball ▪Casting wax Wore samples for 10 min at 2 rpm  20 swipes

11. Wear Assessment: Contact Angle PemPlant Co. 11 Increased contact angle values after wearing

12. Wear Assessment: Bacteria PemPlant Co. 12 Worn Ti samples remained bacterial resistant

13. Stability in Buffer Solution 1 week in Phosphate-Buffered Saline (PBS) Demonstrated bacteria resistant after 1 wk in model biological fluid (n=3) PemPlant Co. 13

14. Conclusion Primary deliverables: ▪PEM deposited on titanium ▪Demonstrated bacteria resistant properties ▪Sustained properties at 4 h bacteria exposure ▪Properties retained after handling simulation, after 1 week in model fluid environment Recommend 2.0/2.0 system Ready for animal studies, industrial implementation PemPlant Co. 14

15. Acknowledgements Prof. Chiang, Todd Thompson Joe Parse, Yin-Lin Xie, Mike Tarkanian Prof. Van Vliet, Prof. Rubner Jenny Lichter, Alan Scwartzman, David Bono 3.042 Classmates PemPlant Co. 15

16. Questions? Visit our website for more information: http://web.mit.edu/3.042/team1_07/ http://web.mit.edu/3.042/team1_07/ Thank you! PemPlant Co. 16 P E M

17. PemPlant Co. Backup

18. PemPlant Co. 18 Wear Assessment: Profilometry Profilometry conducted on Tencor P-10 surface profiler 2 μm radius diamond stylus scans at 6.0 mg 590 μm scan on a scratched film: