AVS 57th International Symposium & Exhibition
    Biomaterial Interfaces Tuesday Sessions
       Session BI1-TuA

Paper BI1-TuA2
Surface Self-Assembled PEG Gel Particles to Control Bacteria-Biomaterial Interactions

Tuesday, October 19, 2010, 2:20 pm, Room Taos

Session: Bacteria on Surfaces
Presenter: Y. Wu, Stevens Institute of Technology
Authors: Y. Wu, Stevens Institute of Technology
Q. Wang, Stevens Institute of Technology
M. Libera, Stevens Institute of Technology
Correspondent: Click to Email
The fact that desirable tissue cells and undesirable bacteria compete for the surface colonization of an implanted biomaterial is now well recognized. When bacteria win this competition, the resulting infection can lead to device failure with substantial consequences to both the patient and the health-care system. We are developing poly(ethylene glycol) [PEG] -based gel particles with which to modify surfaces and differentially control surface interactions with both tissue cells and bacteria. We are particularly interested in modulating the surface cell adhesiveness at micro/nano length scales with the goal of reducing staphylococcal adhesion while still enabling the adhesion, spreading, and proliferation of desirable tissue cells. In short to preserve healing while reducing the probability of infection. We have synthesized anionically charged PEG-acrylic acid (AA) copolymer hydrogel particles by inverse emulsion polymerization and used a bottom-up electrostatic self-assembly approach to modify otherwise cell-adhesive surfaces with cell-repulsive gel particles. Zeta potential measurements confirm that the gel particles are negatively charged because of the acid groups. SEM imaging and dynamic light scattering show that the particle diameters range from ~10's to ~ 100's of nm. We have electrostatically deposited them on both polylysine-modified silicon wafers and titanium metal coupons. By varying the concentration of gel particles in solution and the deposition time, we can control the area density of particles deposited on the substrate surface to levels of ~ 0.1 – 2 particles/sq micron. Immunofluorescence imaging shows that, relative to unmodified Si and PLL primed Si, PEG-modified Si has substantially lower colonization by S. epidermidis after innoculation and 4 hrs of culture. Confocal imaging of PEG-modified surfaces after 4 days of osteoblast culture show good osteoblast spreading and proliferation. SEM images indicate that the osteoblasts grow over the cell-repulsive particles while adhering to the remaining adhesive surface. Such surfaces may be useful in reducing the susceptibility of biomedical devices to biomaterials-associated infection.