Synthesis and characterization of a novel, biomimetic, tribologically enhanced hydrogel for biomedical applications

Abstract

Event Abstract Back to Event Synthesis and characterization of a novel, biomimetic, tribologically enhanced hydrogel for biomedical applications Allen O. Osaheni1, Patrick T. Mather2 and Michelle M. Blum1 1 Syracuse University, Mechanical and Aerospace Engineering, United States 2 Syracuse University, Biomedical and Chemical Engineering, United States Although hydrogels have long been recognized as an attractive candidate for a wide variety of biomedical applications, their use as a synthetic implant in load bearing applications, such as the replacement of damaged menisci or articular cartilage, is severely limited due to their inferior friction and wear properties [1]. Although the presence of zwitterionic brushes have shown tremendous promise for the promotion of boundary lubrication comparable to articular cartilage, the synergistic effects of the functionalization of such polymers to materials that exhibit fluid pressurization mechanism similar to cartilage has yet to be investigated [2][3]. We postulate that blending poly(vinyl alcohol) (PVA) with a zwitterionic polyacrylate prior to gel formation by the freeze-thaw method will result in enhanced surface lubrication due to the strong and pH-independent hydrophilicity of the zwitterionic groups combined with the fluid pressurization mechanism exhibited by the hydrogel. The chemical composition of these tribologically enhanced materials was verified through the use of attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) . Coefficient of Friction (COF) experiments performed via tribo-rheometry in DI water yielded as much as an 80% reduction in average COF compared to that unmodified PVA hydrogel. In addition, the blended samples maintained mechanical and physical properties comparable to the control. These results suggest that the dramatic drop in average COF is attributed to a change in the surface interaction between the articulating surfaces due to the zwitterionic boundary lubricant rather than changes to the physical and mechanical properties of the bulk material. Further characterization of these materials involved quantification of the changes in hydrogel microstructure through the use of wide and small angle x-ray scattering as well as assessment of the size and shape of the wear particles produced during the friction experiments through the use of dynamic light scattering and scanning electron microscopy. Finally, hydrogel biocompatibility was accessed through the use of an L929 fibroblasts cell line with an in vitro cytotoxicity assay. Preliminary results suggest that the tribologically enhanced system does not appear to influence the inherent biocompatibility of PVA. Overall, this study introduces a new platform for the design of advanced materials for use as synthetic implants to repair damaged load bearing tissue as well as a variety of other medical applications in which minimizing COF is an attractive feature. Eric Finkelstein; Wenyang Pan; Leah Anderson