Download Antibacterial Polyelectrolyte Multilayers (PEMs)

Antibacterial Polyelectrolyte
Multilayers (PEMs)
Team X
Maricela Delgadillo
Kay Furman
Yushan Kim
Industrial Application

Implantable Medical Devices:

Pacemakers treat Bradycardia (slow heart
rhythm)


Defibrilators treat Tachyarrhythmia (fast heart
rhythm)


Size: 45x48x8
Size: 62x51x15mm
Potential for Bacterial Exposure



6% of all vascular surgeries result in surgery
site infection (Health Protection Agency)
Packaged and handled sterilely
1-2 hr surgical procedure
Images from http://www.medtronic.com/
Brief PEM Background

Layer-by-layer fabrication




Polycation - Poly(allylamine hydrochloride) PAH
Polyanion - Poly(acrylic acid) PAA
Easy to control pH and number of bilayers
Polyelectrolyte pH affects:


Film Thickness
Interpenetration between layers

Highly ionized polyelectrolytes (pH~6.5) result in thin films


Possible cell adhesion applications
pH~3.0 loopy conformations
Project Plan
Desired
property
Desired
timescale
Material
selection
Validation
Bacteriocidal
Hours
Incorporation of
active: peptide?
e.g. cecropin
No Staphylococcus
epidermidis growth
sepidermidis.mlst.net/
Promote
epithelial cell
attachment
Min.
days/weeks
Film of high
stiffness
Supports fibroblast seeding
Berg, 2000
PEM Design





TiO2 substrate: + charge
1st PEM layer: PAA
PAH/PAA bilayers
Incorporation of antibacterial active by use of
electrostatic charge
Other design considerations


Porosity
Cross-linking
Potential Material Issues

Metal substrate and PEM processing


Titanium use in implantable devices
Previously published studies with metal




PEM on device stimulation electrodes (Patent
5964794, 1999)
PEMs for corrosion-resistant metals (Patent 027011,
2003)
Ti
disk
Necessitates (-) PAA layer deposition first
Imaging Issues


Microscopy requires transparent substrate
TEM or SEM availability
Staph aureus
Further Issues and Questions

Feasibility of bacteria/eukaryote selectivity