Biyomedikal uygulamalar için kitosan tabanlı dağıtım sistemlerinin geliştirilmesi

Chitosan-based delivery systems have gained growing interest due to unique physicochemical properties of chitosan such as biocompatibility, biodegradability, low toxicity, low immunogenicity and cationic nature. Hence, these desirable characteristics of chitosan make it an advantageous biomaterial in wide range of biomedical applications including tissue engineering, wound healing, gene and drug delivery systems. This thesis investigates chitosan as nanoparticle-based gene delivery vehicles and potential drug carriers in biohybrid microrobotic design. In the first part of this thesis, the impacts of three independent variables; PEG chain length, PEG concentration and nanoparticle concentration on transfection capabilities of plasmid DNA loaded and PEGylated chitosan nanoparticles were systematically investigated. First, various PEGylated chitosan polymers were synthesized using different PEG chain lengths (2, 5 and 10 kDa) and PEG concentrations (4, 8, 12, 15 and 20 μmoles of PEG per 25 mg of chitosan). Using altered PEGylated chitosan derivatives, tumor necrosis factor (TNF) α-related apoptosis-inducing ligand (TRAIL) inserted plasmid DNA and crosslinking agent, nanoparticles were synthesized. Synthesized nanoparticles were characterized with dynamic light scattering and scanning electron microscopy. Synthesized nanoparticles were incubated with HEK293-T cells and transfection efficiencies of nanoparticles were experimentally investigated either measuring green fluorescent protein expression or TRAIL protein quantification. With this experimental dataset, we developed an artificial neural network model using (i) PEG chain length, (ii) PEG concentration and (iii) nanoparticle concentration as input variables and green fluorescent expression as output variable. With the help of this computational model, transfection capabilities of nanoparticles with respect to different variables were systematically analyzed with less experimental effort. Overall, this chapter investigates the effect of PEG chain length, PEG concentration and nanoparticle concentration on transfection abilities of nanoparticles and uses artificial neural network as a computational tool to investigate the effect of each parameter on gene delivery studies. In the second part of this thesis, we reported a novel biohybrid algal microswimmer design in which positively charged chitosan polyelectrolytes and superparamagnetic chitosan coated iron oxide nanoparticles attached to negatively charged membrane of C.reinhardtii. Most of the biohybrid designs in literature have limited coating yields, less than 10%. Herein, the novel biohybrid design that we reported has high coating yield which is more than 90%. In this chapter, first magnetic nanoparticles were attached to the membrane of microalgae only in presence of chitosan polyelectrolytes. Experimental conditions for cargo attachment were optimized without compromising the natural motility of C.reinhardtii. Attachment of cargos to the surface of C.reinhardtii were proved using fluorescence microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy. Furthermore, microalgae retained its natural motility and light responsive behaviour with this novel design and this behaviour of biohybrid microswimmer could be used to actuate them in a controlled manner. Overall, this chapter reports a novel biohybrid algal microswimmer design which is promising for controlled drug delivery applications.