Kanser Tedavisinde Gen Taşıyıcı Olarak Kendiliğinden Düzenlenen Peptit Nanopartiküllerin Hazırlanması ve Karakterizasyonu

Abstract

All complex and functional constituents of nature result from self assembly of molecules in thermodynamically stable manner. Production of functional nanomaterials with molecular self-assembly mechanism based on bottom-up approach gained massive importance in last years. The main group of molecules that are capable of self-assembly is the group of proteins. The simple structure of amyloid derived difenylalanine dipeptide is being a hot topic in self-assembly studies with regards to their biodegradability, biocompatibility and the ease of their chemical modifications. In this thesis, FF amide (FFA) and zwitterionic FF (ZFF), two derivatives of difenylalanine (FF) dipeptide, are used to produce nanoparticles as siRNA carriers to be used in gene silencing applications. Regarding the results of the study, FFANP structures are shown to be more stable than ZFFNPs and enhanced as gene carriers for breast cancer therapy. FFANPs having a dipolar character becuase of dipolar and amide groups in FFA dipeptides, aimed to be interacted with negatively charged siRNAs in 3 different ways. Altough encapsulation and adsorption methods for loading siRNA to FFANPs were not applicable, the layer by layer polyelectrolyte deposition method is shown to be successful with zeta-potentials and SEM analysis. In brief, the adsorption first layer on nanoparticle is ensured by the addition of poly-L-lysine (PLL) which is polycationic to FFANP dispersion. The nanoparticle which became cationic with PLL layer is then interacted with polyanionic siRNA, forming peptide-siRNA complex. Nanoparticles are then further interacted with PLL one more time, as a third layer. The nanoparticles are then tested as siRNA carriers for silencing of HER2 gene which has an important role in breast cancer. FFANP-PLL/siRNA/PLL nanoparticles are shown to be better carriers compared to FFANP-PLL/siRNA nanoparticles with the results of real-time PCR and immunocytochemistry analysis. Second layer of PLL is concluded to enhance the uptake of nanoparticle-siRNA complex because of cationic character and to protect the complex from nucleases. Overall, in this study FFANP-PLL/siRNA/PLL nanoparticles are shown to be promising biocompatible and biodegradable nano carriers for gene silencing therapies.