Bioinspired Multifunctional Metal Coatings for Biomedical Applications

This project aimed to design an optimal multifunctional bionanocomposite, which is not only biocompatible and biodegradable, but also has enhanced mechanical strength, toughness, thermal stability, and corrosion resistance properties. These nanocomposites will be capable of storing a higher quantity of anti-inflammatory drugs and will be capable of drug release over a period of time to maximize effectiveness. Implants are commonly used today to treat an ailing joint and are usually made from either titanium or steel due to their biocompatible nature. Yet there is a growing concern that inflammation around the implant as well as debris caused from destruction of the implant could cause complications. The field of biomimetics aims to take solutions found in nature and apply them to the modern world. The unique structure of the red abalone shell, which has platelets of protein dispersed in a calcium carbonate material, can be mimicked in order to develop a stronger material since the red abalone shell has been found to have a high ability to deflect impact force and an ability to resist fractures. Biocompatible polymers were blended with layered double hydroxides (LDHs) in order to bolster the mechanical properties of the polymer. The LDH will not only give the material unique structural and mechanical properties, but also will store the anti-inflammatory drug. Polybutyrate (PBAT) was selected as the polymers to be used due to its biocompatibility and thermal stability. The polymer was then blended with hydrotalcite, a commercially available LDH material, in order to ensure consistency with samples. The synthesis of LDH-ibuprofen was also determined but the synthesized LDH materials were not used in mechanical testing. Samples were tested for thermal stability using a Differential Scanning Calorimeter and it was found that heat of fusion for melting and crystallization decreases with the increase in percentage of LDH. Dynamic Mechanical Analysis shows an increase in storage modulus throughout the temperature axis with increasing percentages of LDH. Nanoindentation is used to test the mechanical properties of thin films and it was found that there was a 340% increase in the average modulus value for 50% LDH PBAT compared to neat PBAT.  Compression testing shows that a 50% LDH-polymer mimicked the stress response of tissue. Thus incorporating LDH materials into the blended polymers yields a material with enhanced structural strength and mechanical properties. These materials can be used to coat metal implants to prevent complications and decrease inflammation around the implant.