The research objective of this Faculty Early Career Development (CAREER) award is to understand two photon induced polymerization (2PIP) of Ormocer(R) organic-inorganic hybrid materials and evaluate the potential of this technology for fabrication of three-dimensional microstructured medical devices. In 2PIP, femtosecond laser pulses from a laser are used to break chemical bonds on photoinitiator molecules within a small focal volume. These radicalized molecules react with Ormocer(R) monomers to create radicalized polymolecules. The desired structures are fabricated by moving the laser focus in three dimensions using a micropositioning system. The key research activities include: (1) biological, chemical, and mechanical characterization of Ormocer(R) materials created using two photon induced polymerization, (2) structural and functional characterization of Ormocer(R) microneedles and microneedle arrays, and (3) functional characterization of integrated drug delivery devices, which combine microneedles with microscale piezoelectric pumps.
This program will also address biomaterials education and underrepresented minority outreach. The PI collaborating with faculty at North Carolina A&T State University on joint research activities, which will provide minority students with hands-on experience in laser materials research; make contacts with minority students and faculty through student symposia; and recruit minority undergraduate students into the UNC/NCSU graduate biomedical engineering program. The PI is also involved with several biomaterials education and training programs, in which the processing, characterization, and application of advanced biomaterials will be discussed. This integrated research and education program will advance the development of medical device microfabrication technologies for the delivery of next generation protein- and DNA- based medicines.
In this project, we examined the structural and functional properties of microneedles prepared using two photon polymerization as well as two photon polymerization micromolding. One factor that has limited widespread use of microneedle technology in medicine is the poor fracture behavior of hollow microneedles that are created using conventional methods. Two photon polymerization involves use of ultrashort laser pulses from a femtosecond laser (e.g., a titanium: sapphire laser) for selective polymerization of photosensitive resins into structures with microscale and/or nanoscale attributes. Two photon polymerization can be set up in a conventional manufacturing location; no dedicated facilities such as cleanroom facilities are needed. In addition, two photon polymerization iscompatible many types of low cost materials, including acrylate polymers and organically-modified ceramic materials. Microneedles may be created with appropriate geometries, dimensions, and features for a given application (e.g., a medical condition in which patient-specific drug delivery is required). Significant findings include: -Microneedles with complex shapes, including out-of-plane shapes, rocket-like shapes, and mosquito-like shapes, have been created directly from computer models by means of two photon polymerization. -Hollow microneedles created using two photon polymerization have been used foto deliver quantum dot solutions to porcine skin. -Two-photon polymerization followed by molding steps may be used to prepare solid microneedles with excellent resistance to fracture. -Antimicrobial microneedles may also be prepared by coating microneedles with antimicrobial materials (e.g., silver and zinc oxide). -The centers of hollow microneedles were filled with chemically modified carbon paste or carbon fibers for detection of biologically-relevant molecules.
