Peptit nanoyapıların biyomedikal uygulamaları

Nature as an important inspirational source for scientists presents complex and elegant examples for adaptive and intelligent systems created by self-assembly. There has been a great endeavour for understanding these sophisticated systems and self assembly gives us an opportunity to emulate these systems by customized molecular designs. In this thesis, next-generation biomaterials were developed by integrating peptide amphiphile molecules into sugar, lipid or inorganic based materials through covalent or noncovalent interactions and their biomedical applications were investigated. Peptide amphiphiles can form morphologically different supramolecular nanostructures based on the amino acid sequence they bear. Also, a bioactive amino acid sequence can be inserted into the peptide backbone not only to enhance the biocompatibility of the material but also to direct cellular responses. On the other hand, amphiphilic character of peptide amphiphiles enables to interact with other amphiphilic molecules or hydrophobic surfaces via hydrophobic interactions. In the scope of the present thesis, peptide based systems were utilized in three different biomedical applications: drug delivery, bioimaging and regenerative medicine. In the first chapter, the self-assembly as one of the bottom-up approaches, peptide self-assembly, the forces and factors triggering the peptide assembly, the importance of peptide amphiphile design in the resulting nanostructure and the biomedical applications of peptide amphiphiles are shortly introduced. In the second chapter, a new drug delivery system is devised by incorporating peptide amphiphile molecules, which are synthesized using arginine residues that are known to enhance cell penetration, into the liposomal system. Beside the investigation of model dye and anticancer drug encapsulation capacities of the prepared formulation, cellular uptake profiles and therapeutic effects of liposomal systems are also examined. In the third chapter, mesoporous silica nanoparticles, which are anticipated to be used in drug delivery and theranostic applications, are individually functionalized with two distinct peptide amphiphile molecules with different overall charges and their biocompatibilities and cellular uptake profiles are examined. In the fourth chapter, superparamagnetic iron oxide nanoparticles that have also potential to be utilized in clinical applications are shown to be applicable as negative contrast agents in magnetic resonance imaging after coating with peptide amphiphiles. The last chapter covers the development of glycopeptides nanofibers that can mimic natural hyaluronic acid abundantly found in native cartilage tissue and its effect on the cartilage regeneration.