Self-assembling polymer hydrogels have numerous advantages that make them ideal candidates for use as biomaterials. High water content, desirable pore structures and bioresorbability are just a few of the characteristics that these systems share with native human tissues. Tuning the structure of hydrogel polymers or adding a second component to create nanocrystalline domains forms composites similar in structure to naturally occurring tissues and materials.

My research focuses primarily on the synthesis and characterization of biomimetic nanocomposite materials. Additionally, I have conducted mammalian cell culture analysis to determine the effectiveness and cytotoxicity of selected biomaterials. These studies were carried out using the HepG2 (human hepatocellular liver carcinoma) cell line and primary bovine chondrocytes that we isolated from calf knee joints.

Materials that I am researching are similar in composition, morphology and physical properties to bone, one of the most ubiquitous examples in nature of biocomposites and biomineralization. For my investigation I am determining how environmental factors influence the in situ formation of calcium phosphate crystals in block copolymer gels. This parallels the growth of bone, which is formed by ion diffusion and apatite mineral growth on oriented Type I collagen polymers.

Factors such as pH, temperature and ionic strength influence the mineralization process in many ways. These effects range from determining the type and size of crystals produced to the overall mineral content of the composite. Because environmental and experimental variables determine the final composition and structure and thusly the physical properties of the material, a great deal of work is focused on characterizing the composites after they are formed.

In order to determine what calcium phosphate crystal phases are present in my samples I conduct powder X-ray diffraction (XRD) on the composite mineral. Energy dispersive X-ray spectroscopy (EDS) discerns relative ion (i.e., calcium to phosphate) ratios and can substantiate the results of XRD. Scanning electron microscopy (SEM) is used to investigate the overall micro- to nanostructure and particle size distribution of the mineral particles. Bulk mechanical properties are tested rheologically to illustrate the effect of calcium phosphate crystals on the elastic modulus of the gel.

By applying fundamental principles of chemistry to tune in situ nanocomposite formation we are able to produce biomaterials that may have improved biological functionality. Establishing the biocompatibility and effectiveness of these composites through cell culture experimentation techniques and biological assays will give us the final word on the direction we will take to create more useful biomaterials.