The objective of this award is to explore new composite nano-manufacturing methods to enhance mechanical integrity of biopolymers and to investigate a new micro porous structure which will assist in bioactive material delivery in surgical devices. The approach will be: 1. Conduct biomaterials and nano-diamond (ND) composite research to optimize the polymer/ND interface and mass production technique to manufacture ND reinforced biopolymers. 2. Identify suitable structural and bioactive materials for a strong fixation device body and efficient bone/tissue healing and growth. 3. Research on a new technique: gradient cellular structure to generate bio-reagent storage and passage micro pores to not only assure the device mechanical strength but also assist in bioactive materials delivery. 4. Conduct various mechanical and biological testing to find, control, optimize and integrate all required functionalities for the surgical device.
The benefits and broader impacts of this research will be: Provide an innovative way to increase the mechanical integrity of biomaterials and replace current passive orthopedic surgery devices with active devices; a strong relationship with Arthrex, Inc. will be built for the new technology development and transfer; three doctoral students and two senior design teams will be trained; engaging students with design projects in nanomanufacturing, bioactive fixation devices and bio-reagents delivery. The project will be used in outreach workshops for local high school and community college students, including many underrepresented minority students to showcase high-tech nanomanufacturing and surgical engineering applications.
The main objective of this GOALI collaborative research project is to explore new composite nano-manufacturing methods to enhance mechanical integrity of biopolymers and to design a new micro-structure which will assist in bioactive material delivery. This project is expected to design a creative interference screw that has the similar internal structure of natural bone with sufficient mechanical strength improved by functionalized nanodiamond and bioactive ability to overcome the shortage of conventional interference screws. Key findings: We have generated ND-ODA/PLLA composites with up to 10%wtND-ODA with uniform ND-ODA dispersion and good affinity between the matrix and the filler. The mechanical properties of NDODA/PLLA composites were improved dramatically with the additionof ND-ODA: 1%wt of ND-ODA increased the hardness of the composites by the factor of 4; 10%wt of ND-ODA resulted in almost an order of magnitude higher hardness, 3 times higher Young’s modulus, and reduced creep. Cytotoxicity and biocompatibility experiments in concert with osteogenic marker gene expression analysis demonstrated that both ND and ND-ODA are nontoxic to murine osteoblasts, and support cell proliferation and differentiation in vitro. The combination of these properties with intrinsic fluorescence and tunable biodegradability makes the ND-ODA/PLLA composites promising materials for bone tissue engineering and regenerative medicine. The good affinity of nanoparticles to the polymer led to significant increase in both the tensile strain and fracture energy of the nanocomposites.Addition of 10% wt of ND-ODA resulted in a 280% increase in the strain to failure and a 310% increase in fracture energy compared to neat PLLA. Both of these parameters are crucial for bone tissue engineering and for manufacturing of orthopedic surgical fixation devices. Nanocomposites with varying ND-ODA contents were used as matrices for the bio mineralization in SBF. Based on SEM, EDS,XRD, and FTIR, the apatite particles formed on the scaffolds were similar to the apatite in natural bone, demonstrating for the first time successful growth of apatite on ND-ODA/PLLA composites. Apatite nucleation and growth occurred faster on the composites containing ND-ODA than on pure PLLA. With higher contents of NDODA,more apatite particles grew on ND-ODA/PLLA surfaces. The increased mechanical properties and enhanced bio mineralization make ND-ODA/PLLA composites a promising material for bone tissue engineering, bone surgical fixation devices, and regenerativee medicine. Impact products: 1. The first place in Ceramographic Competition organized by The American Ceramic Society. The poster title received of this award is: Fluorescent Nanodiamond Reinforced PLLA Scaffolds For Tissue Engineering and Bone Repair, Oct. 2010. 2. Patent US2010/051176, Publication Date: April 07, 2011, Functionalized Nanodiamond Reinforced Bio-polymers and Its Application in Surgical Fixation Devices. 3. More than 5 professors, two research scientists, 4 Ph.D. students (they all graduated now) and many master and undergraduate students participated in this existing project. 4. More than 5 journal papers, numerous conference papers, presentations, seminars, were delivered based on this research. 5. OrthoMend Corp. a biomedical company has licienced our patent of nano diamond reinforced polymer composite. 6. Our GOALI industrial partner, Arthrex, Inc. has been active participate the project, we had annual conferences, university-Industry visiting, tele-conferences, extensive phone call, emails and technical consulting and communications. Industrial partner played a significant role in the project. The company provided biomaterials testing data, manufacturing data, and several thousands of PLLA polymers, and medical screws, pins and devices.
