| Substantial improvements in current therapies and diagnostics will occur using new methods for the delivery of drugs and imaging agents. Core-shell protein or polymer microspheres are biocompatible vesicles that have been used to meet the goal of transporting drugs or contrast agents to diseased tissues via the circulatory system. They consist of a hydrophobic core surrounded by a protein or polymer shell. Typically, these spheres had been formed sonochemically from bovine serum albumin and were stabilized by inter-protein covalent crosslinking of cysteine residues. In this thesis, I have developed a nanoscale protein sphere through the addition of surfactants to the sonication solution. Spheres with diameters of 300 nm were created and have been shown to be robust. In addition to decreasing the size of the protein microspheres, this thesis contains the development of coreshell spheres made from other polymers. These spheres are held together through strong hydrogen bonds or ion bridges rather than covalent bonds, but are stable and would be useful for biomedical applications. The polymer spheres were also formed using methods other than sonication including sparging, extrusion and blending. A new imaging technique, magnetomotive optical coherence tomography (MMOCT), was developed in conjunction with the Boppart lab to image the microspheres in vivo. This system uses encapsulated magnetite in a modulated magnetic field to image diseased tissues. The microspheres were also targeted to tumor cells via an RGD motif (arg-gly-asp) which has been shown to target integrin receptors that are more prevalent on tumors than healthy tissue. In conclusion, I have developed a nanoscale, targeted sphere that can be imaged in vivo. |
