Dr. Yun has been investigating biomaterials, conducting biocompatibility studies, and developing biomedical devices for over 17 years. Although many materials are available only few are suitable for the biological environment of the human body. With my expertise, out research team has developed novel materials for applications in the biomedical engineering. The following are few examples.
L-tyrosine based polymers are designed from an amino acid. Instead of using peptide bonds to polymerize the amino acids, we have modified the structure with two linkers. The first linker is an L-dopa analog. The second linker (M) can consist of wide range of compounds to fit the desired application. To date, we have synthesized five polymer with varying materials and biological properties. The materials are not toxic to cells, have excellent properties for use in biomedical devices, and cab even be blended with each other to enhance their utility.
L-tyrosine polyphosphate (LTP) is a rapidly degrading polymer that is ideal for nanoparticle applications. Our research group has made nanoparticles encapsulated with DNA for gene therapy, low-molecular-weight drugs, proteins, and peptides.
L- tyrosine polyurethanes (LTUs) are slow degrading. The advantage of LTUs is their excellent elasticity, as good as commercial non-biodegradable polyurethanes. The ideal application of LTUs is tissue engineering, since this field lacks biodegradable and elastomeric materials that are also biocompatible.
Hyaluronan (HA) is a polysaccharide that is native to our bodies. It is found in many tissues, including our joints and in the extracellular space. It is DFA approved for viscosupplementation, has excellent biological properties, and is an excellent biomaterial for many applications. Our laboratory has the ability to prepare HA into microspheres, sponges, scaffolds, fibrous membrane using electrospinning, and for conjugating drugs.
Chitosan is a deacetyled from of chitin, which is derived fro the exoskeleton of crustaceans. Since chitosan have very limited solubility in common aqueous and organic solvents, we have grafted PEG on the polymer's backbone. PEGylated chitosan is amphiphilic, and we primarily use it to surface-modify our nanoparticles, microspheres, and electrospun fibers. The PEG groups can also be used for further conjugation of targeting molecules.